55 Commits

Author	SHA1	Message	Date
Andrew Kesterson	f005b88980	Let a program say what part of a sprite collides ... `SPRHIT n, kind [,x1, y1, x2, y2]` gives a sprite a collision shape: a box, a circle inscribed in it, or a capsule. `RSPHIT(n, f)` reads it back in SPRHIT's own argument order, the way RSPRITE and RSPPOS already do, and needs no device because it answers from interpreter state. The rectangle is two corners measured from the sprite's top-left, in device pixels -- the same `x1, y1, x2, y2` that `BOX` and `SSHAPE` take. A dialect with two spellings for a rectangle is one nobody can write from memory. Omit it and the shape fits whatever the picture turned out to be, which is what a sprite loaded from a file needs: `SPRSAV "ship.png", 1` takes the image's own size and the program never learns what that was. **A sprite nobody has shaped collides with its whole frame, expansion bits included, exactly as before.** That is a promise rather than a convenience, and it has its own test: the same two sprites in the same two places, once with no SPRHIT and once with a four-pixel box, reporting a collision and then not. Named SPRHIT rather than SPRSHAPE because "shape" already means "a region SSHAPE saved" in this dialect, in this very chapter -- `SPRSAV A$, 1` takes one -- and a reader who typed `SPRSHAPE A$, 1` would have had every reason to. Both names, and RSPHIT, were grepped against every label in docs/, examples/ and both corpora first: a bare word is a label here, so a verb and a label share one namespace and taking a name a checked-in listing already uses would break it silently. `SPRHIT n, 0` takes a sprite out of collision while leaving it on the screen -- the ghost, the flashing invulnerable player, the pickup already taken. Hiding it with `SPRITE n, 0` stops it colliding too, and is what you want when it should not be seen either. The circle answers the complaint chapter 8 already ships a figure of. That figure shows two discs whose *boxes* touch at a corner while the artwork is nowhere near, and `BUMP(1)` reporting a collision; two `SPRHIT n, 2` and it stops. The test asserts both halves so the figure's caption stays true. `tests/verbs_table.c` caught RSPHIT filed after RSPPOS rather than before it, which is the sorted-table test doing exactly the job it exists for. Docs: a new section in chapter 8, rows in the verb and function references in alphabetical order, and chapter 13's "collision is by bounding box" becomes "collision is by shape" with the addition named. 111 with akgl, 110 without, and the artwork breakout still runs clean. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EwxGB6TdoVvZ11KQQME9cL	2026-08-02 10:01:33 -04:00
Andrew Kesterson	f06c53110d	Answer sprite collision through libakgl's narrowphase ... `spr_collisions()` computed axis-aligned overlaps itself, because at libakgl 0.7.0 there was nothing to delegate to: `akgl_collide_rectangles()` has a documented corner-containment defect and the physics backend's `collide` slot raised "Not implemented". 0.8.0 brought a real narrowphase, and this moves onto it. The mask is bit-identical and every test from the previous commit passes **unmodified**, which was the gate this stage had to clear -- including the two that were written to be hard to satisfy. Edge-to-edge is still not a collision, so a tile-aligned program is unaffected. The cross-shaped overlap is still reported, which is the one that could have regressed: it is the case `akgl_collide_rectangles()` gets wrong and the reason the hand-written loop existed, and `akgl_collision_test()`'s box path gets it right. What it buys is the contact -- a normal, a penetration depth and a point -- which four comparisons cannot produce. Nothing consumes it yet; that is the next commit. It is here now because the mask and the contact come out of the same test, and computing them in two places would be two things to keep in step. **The first attempt was ten times slower and the benchmark caught it.** Syncing all eight proxies and running the narrowphase on all twenty-eight pairs measured 984 ns a scan against 96 ns for the loop it replaced -- 21% of a frame at 256 scans a frame -- to produce a mask that was bit-identical and a contact that was thrown away. Two changes fixed it, and both are what a broad phase *is* rather than workarounds for a slow library: - **Reject on the bounding boxes first.** The four comparisons that were always here now decide which pairs are worth an exact answer. The narrowphase still decides the bit -- the box test only says "maybe", which will matter the moment a shape is not the whole frame. - **Do not sync a proxy that has not moved.** The scan runs at the top of every interpreter step and a sprite moves at most once in that time, so almost every sync would rewrite a proxy with what it already holds. Compared against the last synced rectangle rather than flagged by the verbs, because a host game can move a BASIC sprite through the actor registry and a flag would miss that. Measured after: 54.9 ns at eight sprites spread out, which is *faster* than the 96.3 ns it replaced -- boxes are now built eight times a scan instead of fifty-six. The number that matters is the new benchmark row for the arrangement `examples/breakout/sprites/breakout.bas` actually has, which is 211.8 ns, or 4.5% of a frame. That game reaches it because two of its eight sprites are the screen -- a captured HUD strip and a captured play field -- so the field's box covers everything and those pairs can never be rejected. Roughly double the old cost, for contacts. Recorded in MAINTENANCE.md with the two synthetic extremes either side of it as a bracket. The eight proxies are claimed once at init and held, so exhaustion of the pool shared with an embedding host is an initialization failure that names the pool rather than a collision scan refusing halfway through somebody's game. The shape is built before the proxy is spawned from it and the acquire sits adjacent to the initialize, which are two traps libakgl hit itself and documents. `tests/akgl_backends.c` now tears the sprite backend down between cases. It never did, and got away with it while init claimed nothing; eight proxies apiece across twenty cases is a hundred and sixty against a pool of a hundred and twenty-eight. A host releases what it took, and so does the harness. Both games run forty seconds headless with no error line. 111 with akgl, 110 without. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EwxGB6TdoVvZ11KQQME9cL	2026-08-02 09:48:11 -04:00
Andrew Kesterson	d61e352f36	Test the collision scan, and measure what it costs ... `spr_collisions()` had no test. `tests/sprite_verbs.c` drives the collision path end to end but through a mock backend, so the real overlap arithmetic in `src/sprite_akgl.c` could have changed what `BUMP(1)` reports for every program in existence and the suite would still have printed 110/110. That gap is closed here, before anything touches the arithmetic, so that there is a *before* to compare an *after* against. Six cases against the real akgl backend: nothing defined, two sprites overlapping, edge-to-edge, a hidden sprite, and the x-expand bit doubling the box that collides rather than only the one that draws. Edge-to-edge earns its place -- the test is a strict `<`, a tile-aligned program puts sprites there constantly, and a replacement answering "touching" instead of "overlapping" would change every one of them silently. **The seventh is the cross-shaped overlap**, and it is the one to watch. A tall thin sprite crossing a short wide one overlaps without either rectangle holding a corner of the other; `akgl_collide_rectangles()` is documented as answering "no" there, which is why `src/sprite_akgl.c` does the four comparisons itself rather than calling it. Two further assertions stop that test passing by accident: each sprite is moved clear along the axis it is supposed to be short on, so a sprite that came out the wrong size fails rather than quietly reporting an ordinary overlap. `tests/collision_perf.c` answers the question nobody had measured. The service runs at the top of every interpreter *step* and the frontend takes 256 steps per rendered frame, so a busy program scans up to 256 times a frame over sprites that have not moved. At RelWithDebInfo, scale 10, best of 5: the scan is 96.3 ns at eight overlapping sprites and 19.4 ns at none, against a rendered frame of 1.17 ms. **256 scans is 24.7 us, or 2.1% of a frame, in the pathological case, and 0.42% for a program with no sprites.** So the per-step cadence stays. It is what makes a collision report describe where the sprites have just been moved to rather than where they were, and 2% of a frame in a case no real program reaches is not worth changing when a handler fires for every program that already works. The numbers and that conclusion are in `MAINTENANCE.md` so it does not get re-argued. The benchmark borrows libakgl's `benchutil.h` by include path rather than copying it, the way the fixture font is already borrowed, and is labelled `perf` so `ctest -LE perf` can leave it out. It runs at scale 1 in the ordinary suite -- 1.2 seconds -- because a benchmark nothing ever builds is a benchmark that rots. Both suites green: 111 with akgl, 110 without. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EwxGB6TdoVvZ11KQQME9cL	2026-08-02 09:25:22 -04:00
Andrew Kesterson	89fca8007b	Assert the log line a failed report leaves behind ... A mutation run over src/runtime.c found that deleting the `LOG_ERROR_WITH_MESSAGE` in `report_and_reraise()` left the whole suite green. That line *is* the visible half of the "a failed report must not swallow the program's own error" fix -- without it the secondary failure goes nowhere and the only evidence is the original error still being the one raised. Nothing looked at it, so nothing noticed. `tests/trap_verbs.c` now redirects `akerr_log_method` into a buffer and drives the path with a sink that refuses every write, which is the only way left to make reporting fail now that the `TRAP` dispatch no longer allocates. It asserts the log line and that `errclass` still records the program's own error, and it kills the mutant. TODO.md gains a section for what the run found and what it did not: it was cut off at 551 of 997 mutants after ninety minutes, so 446 are unexamined and a full run belongs in the release workflow rather than here. The three regions this work touched were all covered, and the survivors in the skipped-block guard are named and assessed -- three of the four are equivalent for any program that can actually be written, and the one that is not would need a test with a loop on line 1. Also recorded: src/variable.c at 68.2% with every mutant on the inline-storage lines killed, and src/runtime_trap.c at 82.5% with no survivors in `set_error_variables()`. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-02 02:17:17 -04:00
Andrew Kesterson	c8b917d205	Write down that the left operand decides integer or float arithmetic ... No behaviour change, by decision. `A# * 0.45` is 0 and `0.45 * A#` is 1.35, because every operator branches on `self->valuetype` and converts the right operand to match. It is inherited from the Go reference, a C128 promotes to float instead, and this interpreter is at least consistent about it -- so a dialect saying the left operand wins is a defensible position, and changing it to promotion would alter the result of every mixed expression in every existing program. **The defect was that nobody said so.** Chapter 3's "Numbers" did not mention it, Chapter 13 did not list it among the differences, and nothing fails when a program gets it wrong -- it computes something else and carries on. The game in examples/ lost its per-level speed increase to `5.6 + LEVEL# * 0.45` evaluating to a flat 5.6, and bled velocity out of every bounce through `0 - BLVX%(B#)` quantising to whole pixels. Both read correctly. Neither produced a diagnostic. Now said in three places: a section in Chapter 3 with the demonstration and the two rules that keep a program out of it (put the float on the left, put the answer somewhere with a `%` on it), a row in Chapter 13 naming it as the difference from 7.0 most likely to turn a working listing into a quietly wrong one, and the reasoning on value.h where the operators are declared. tests/value_arithmetic.c pins it in both directions across multiply and subtract, with a comment saying it is the documented contract rather than an accident -- so promotion becomes a decision somebody takes deliberately rather than a change that could slip in under a passing suite. TODO.md section 9 item 4, struck as a documentation outcome. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-02 00:23:20 -04:00
Andrew Kesterson	d5f3c3ef5b	Accept GRAPHIC CLR and a negative DATA item ... Two parse handlers refusing something the documentation promises. Landing together because they are the same defect twice -- a verb's own argument shape falling through to a general path that cannot see it -- in one file, found by one program, and verified in one pass. **`GRAPHIC CLR`** is given as `GRAPHIC mode | CLR` in both docs/06-graphics.md and docs/11-verb-reference.md, and was refused: `CLR` is a verb of its own, so the generic arglist path scanned it as a command token and the expression parser answered "Expected expression or literal". `akbasic_parse_graphic()` takes it as this verb's keyword argument and emits mode 5 -- which `akbasic_cmd_graphic()` already treats as "drop the saved shapes and go back to text", so both spellings are one statement and the exec handler is untouched. The documentation was right all along; nothing in it changes. **`DATA -5`** was refused by `akbasic_parse_data()`, and only there: `READ` scans the source text directly (src/data.c) and always returned the -5 intact. So the value was right and *reaching* the statement raised -- which, since section 4 settled that `DATA` at run time is a no-op, is what a program does with every `DATA` line it walks past. A table of coordinates or velocities is full of negative numbers, which is how a game found it. The fix accepts a unary minus over a numeric literal and nothing else: `DATA -A#` is still a mistake worth naming, and `akbasic_leaf_is_literal()` keeps meaning what it says because other callers rely on it. tests/read_data.c covers both mechanisms -- reading a negative item and reaching the line after it -- with a mixed-sign table and a negative float, since the two were never the same code path. TODO.md section 9 items 7 and 8, struck. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-02 00:18:53 -04:00
Andrew Kesterson	a1dcfcacf3	Land a character written past a short row's terminator ... A grid row is a NUL-terminated string, and `putchar_at()` wrote the character, advanced and terminated -- so `CHAR 1, 40, 1, "#"` on an otherwise empty row stored the `#` at column 40 with `text[1][0]` still `'\0'`, and the render loop, which stops at the terminator, drew nothing at all. The silent nothing is the trap. The write succeeded, the cursor moved, the stdout mirror showed the character, and only the window stayed blank -- so the program looked right everywhere except where it mattered. The documented truncation on the way *back* is fine and is unaffected. `putchar_at()` now fills the gap with spaces before storing. **Padded there rather than in `sink_moveto()`**, which TODO.md proposed: this way `moveto` stays read-only -- the objection that entry raised against its own suggestion -- and a row is only ever padded when a character actually arrives. The pad fills from the terminator rather than replacing it. The buffer is not cleared between rows, so replacing only the terminator would expose the tail of whatever longer row used to be there: writing "ABCDEFGHIJ", truncating it to "ABCX", then writing at column 7 must give "ABCX Z" and not "ABCX FGZ". tests/akgl_backends.c asserts all three cases, and the middle one keeps the truncation pinned. TODO.md section 6 item 32, struck. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-02 00:13:42 -04:00
Andrew Kesterson	8594d8471d	Honour a subscript in SSHAPE and GSHAPE ... `shape_variable()` took the identifier off the leaf and looked the variable up without ever evaluating the subscript, and both verbs then addressed element zero with a literal. So `SSHAPE SH$(2), ...` wrote the handle into `SH$(0)` and `GSHAPE SH$(2)` stamped whatever was in `SH$(0)`. Ordinary assignment and `PRINT` honour the subscript, which is what made this expensive: a program keeping several saved shapes in an array got every one of them resolving to the same element, silently, and the only symptom was that every stamp came out as the last shape captured. The Breakout in examples/ keeps its six brick stamps in six separate scalars for exactly this reason. `SPRSAV` was the counter-example and is the model -- it evaluates its argument and handles an array element correctly. The subscript resolution itself is now shared: `collect_subscripts()` comes out of src/environment.c as `akbasic_environment_collect_subscripts()`, so a verb taking a variable by name resolves a subscript the same way assignment does rather than each verb deciding for itself. tests/graphics_verbs.c covers TODO.md's reduction -- which used to print "[SHAPE:0] []" and now prints "[] [SHAPE:0]" -- and the case a program actually wants: two shapes captured into two elements, each stamped back through its own, asserted against the device log so a fix that merely made the strings look right would not pass. Chapter 18's trap 4 becomes history, and Chapter 6 says an array works. TODO.md section 9 item 6, struck. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-02 00:10:24 -04:00
Andrew Kesterson	694b446ce4	Let a program ask how big the text grid is ... `RGR(1)` and `RGR(2)` gave the window in pixels and nothing gave columns, rows or the cell size -- so anything placing a character *and* a sprite at the same spot had to hardcode a number measured by hand against whatever font the host loaded. The Breakout in examples/ does exactly that, `CW# = 16`, and it is the one thing in that listing that breaks on a different font or window. **`RWINDOW` is BASIC 7.0's own answer and had never been implemented here.** `RWINDOW(0)` is the current text window's rows and `RWINDOW(1)` its columns. `RWINDOW(2)` reports a C128's 40 or 80 column screen mode, and this interpreter has neither -- refused by name, because answering 0 would be a plausible lie, which is worse than a refusal that says why. The cell size in pixels is `RGR(3)` and `RGR(4)`, beside the surface's own dimensions rather than on `RWINDOW`. Two reasons: a cell size is a fact about the surface, and `RWINDOW` reports the *window*, so dividing `RGR(1)` by a column count stops being right the moment a program calls `WINDOW`. Both read a new optional `grid` entry point on `akbasic_TextSink` -- columns, rows, cell width, cell height -- implemented by the akgl sink and forwarded by the tee, in the shape `moveto` and `window` already had. NULL everywhere else, so both verbs refuse by name against a sink with no grid. `akbasic_sink_init_ stdio()` clears it for the same reason it now clears the other two. Measured on the standalone build: `RGR(3)` answers 16 and `RWINDOW` answers 50 columns by 37 rows -- the three numbers the Breakout listing had written out as constants -- and `RWINDOW` follows a `WINDOW` call while `RGR(3)` does not. tests/console_verbs.c drives the answers through a stand-in sink with a grid, since the harness sink is stdio and has none; tests/graphics_verbs.c covers the new `RGR` fields, their refusal, and the moved range bound. The `c excerpt=` block in docs/10-embedding.md moves with the header, which is `docs_examples` doing its job. TODO.md section 6 item 31's second half, struck. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-02 00:05:17 -04:00
Andrew Kesterson	fd1f0d7c19	Forward WINDOW through the tee sink ... `akbasic_sink_init_tee()` wired write, writeln, readline, clear and -- conditionally -- moveto, and never `window`. The standalone AKGL frontend runs the interpreter against a tee, so the fully implemented `sink_window()` underneath it was unreachable: `WINDOW 0, 0, 20, 4` answered "WINDOW needs a text device with a character grid, and this one has none" on the one build that has a character grid. It reads as an oversight rather than a decision, because `moveto` directly above it is forwarded with reasoning that applies unchanged. `tee_window()` is that function, modelled on `tee_moveto()`, offered only when a half can take it so the refusal still reads correctly through a stdio-only pair. **Writing the test found a second one.** Both optional entry points are assigned conditionally, and neither initializer cleared them first -- so a caller with a sink on the stack got whatever was in that memory, and `CHAR` and `WINDOW` decide whether they can act by testing those pointers for NULL. Both `akbasic_sink_init_tee()` and `akbasic_sink_init_stdio()` now clear them. An initializer that leaves a field alone is not an initializer. tests/sink_tee.c gains a stand-in sink with a grid -- the two stdio halves have neither entry point, which is exactly why they could not show that either is forwarded -- and asserts both directions, the arguments arriving intact, and that a grid-less pair still offers neither. Verified end to end: `WINDOW 0, 0, 20, 4` then `PRINT` succeeds under build-akgl/basic and still refuses by name under build/basic. What this does *not* fix is that a drawing still has to be re-issued every frame: the frontend never clears and SDL is double-buffered, so a drawing issued once appears in one buffer only. Shrinking the text area makes the rest of the window the program's; keeping something there is still the program's job. That half is documented rather than fixed, and is filed as TODO.md section 9 item 5. TODO.md section 6 item 31, struck. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 23:57:57 -04:00
Andrew Kesterson	5d33237eed	Release the scope a skipped BEGIN block's loop pushed ... `akbasic_parse_for()` and `akbasic_parse_do()` create their environment while the line is *parsed*; whether to skip it is decided afterwards, when the line is evaluated. So a loop inside a block that was not taken pushed a scope, its body was skipped, and the `NEXT` or `LOOP` that would have popped it was skipped too. Nothing else ever would. At the top level that exhausted the pool after thirty-two skips. Inside a routine it was far more confusing: the orphan sat between the routine and its caller, so the `RETURN` after the block reported "RETURN outside the context of GOSUB" from a routine that plainly *was* entered by a `GOSUB` -- naming the one construct that was not at fault, which is why it cost an evening to find. The skip now releases what parsing pushed. **Narrower than it first looks.** Releasing on any skip breaks tests/reference/language/flowcontrol/nestedforloopwaitingforcommand.bas: a zero-iteration `FOR` skips its body by the same mechanism, and there the orphan is load-bearing -- it absorbs the inner `NEXT` so the outer `NEXT` still finds its own `FOR`. Releasing it turns that case into "NEXT outside the context of FOR". So the release is conditional on the skip being a *block* skip, which is decidable because nothing inside a skipped block ever runs to arm a `NEXT` wait. Both halves are asserted side by side in tests/structure_verbs.c, the second one citing the golden case that caught it. The forty-skip case names its own step budget: a skipped line is not free, and forty passes over a five-line block cost about 2700 steps against the shared runner's 2000. Chapter 18's trap 3 becomes history rather than a warning, and the note in Step 5 that called `GOTO`-guarded loops "not a style choice" now says why the shape is kept anyway. TODO.md section 9 item 2, struck. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 23:55:10 -04:00
Andrew Kesterson	f5a35b4af6	Enter a TRAP handler when the variable table is full ... Two separable faults, both on the path a program takes when it is already in trouble. `akbasic_trap_set_error_variables()` reached `ER#` and `EL#` through `akbasic_runtime_global()`, which *creates* a name the program never used -- and creating one takes a variable slot. So a program that had filled the 128-slot table could not have its handler entered at all, and because the failure happened inside the error path rather than raising, nothing was reported and the program carried on with the failing statement's effect quietly missing. A wrong answer delivered as a right one, which is worse than an abort. `akbasic_runtime_reserve_globals()` now creates both at runtime init, where there is always room, and `clear_variables()` puts them back after `CLR` and `NEW` empty the table. Second: `report_and_reraise()` used a plain `PASS` around the report, so a failure while reporting *replaced* the error the program had actually made -- "Maximum runtime variables reached" in place of the subscript that was out of range. The secondary failure is now logged and the original is re-raised, which is what a user needs to hear. **The reduction in TODO.md no longer reproduces, and not because of this.** The value-pool fix in the previous commit made a scalar free, so the pool can no longer be emptied by creating names. The defect was still live through the variable table: 124 names and a TRAP armed, and the handler was silently skipped. That is what the new test in tests/trap_verbs.c pins, together with the invariant -- both globals present before a program runs. Verified by reverting the fix against the new tests: both fail, and the second prints the log line the swallow used to eat, "could not report a BASIC error 515 (Out Of Bounds): Maximum runtime variables reached". TODO.md section 6 item 33, struck. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 23:48:56 -04:00
Andrew Kesterson	05f241aca1	Stop a scalar created inside a scope costing value-pool slots ... A scalar now lives in the variable record (`akbasic_Variable::inlinevalue`) rather than drawing from the value pool, so a `GOSUB` local, a `FOR` counter and a `DEF` parameter cost nothing at all. The pool is a bump allocator with no free, and its comment justified that with "nothing in BASIC destroys a variable". Scope exit does: it marks the variable slot unused, `new_variable()` memsets the slot it hands back -- clearing `values` -- and `variable_init()` therefore took *fresh* slots for a variable whose old ones were still counted. Every scope that created a local leaked, with no diagnostic until the pool ran dry on whichever line happened to be unlucky. Six thousand `GOSUB`s creating one local used to die on the 4091st at `LOC# = 1` with "Array of 1 elements does not fit in the 0 remaining value slots". They now run. A `DEF` called eight thousand times used to die between the four and five thousandth -- the leaking slot was the call scope's parameter, which is a scalar -- and both forms now run. A game creating one name per tick was dead in half a minute; the Breakout in examples/ was, after twenty-five seconds. **A `@` name is the one exclusion, and it is the whole of it.** A structure or a pointer to one keeps pool storage, because a pointer into a record outlives the scope that DIMmed it -- docs/16-structures.md says nothing is reclaimed and `prev_environment()` relies on it. The name suffix is the right test rather than `structtype`, which the DIM path sets *after* calling `variable_init()`. A local array therefore still leaks, deliberately, and is now the narrow rule the tutorial teaches. `SWAP` needed the other half: it copies whole variable records, so the `values` pointer that came over named the other variable's inline slot -- which by then held this variable's own old value -- and SWAP silently did nothing. Caught by tests/language/housekeeping/verbs.bas, which is the golden corpus earning its keep. tests/value_pool.c is the new coverage. It asserts the mechanism as well as the consequence: a later change that moved arrays inline too would pass every behavioural case and quietly break the pointer guarantee. The sharpest case takes the pool's whole 4096 slots in four arrays after two hundred scope entries, so one leaked slot has nowhere to go. Chapter 17 Step 3 taught "declare every name at the top" and no longer needs to. It now teaches what is still true -- a name first seen inside a subroutine dies at RETURN, so a routine cannot answer its caller through one -- and its demonstration is the array case, which still fails. TODO.md section 6 item 30 and section 9 item 1, both struck. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 23:47:49 -04:00
Andrew Kesterson	cb0e2d0800	Add two Breakout examples and the tutorials that build them ... Two complete games in `examples/breakout/`, both 100% BASIC: `characters/` draws its wall in the text grid with two `DATA` sprites for the ball and paddle, and `sprites/` loads CC0 artwork and captures its whole screen with `SSHAPE`/`SPRSAV`. They take opposite shapes for reasons that are entirely this interpreter's, which is what the chapters are for. `docs/17-tutorial-breakout.md` and `docs/18-tutorial-breakout-artwork.md` build each one a step at a time, and end in a checklist of the rules a real program runs into: create every name before the loop starts, write a text row whole, loop with `GOTO` rather than `DO`, put the float on the left. Every trap is a runnable block with its own output rather than a claim -- the value pool dying at four thousand names, the skipped `BEGIN` block that breaks its caller's `RETURN`, `SSHAPE` ignoring a subscript, `READ`'s single cursor. Five figures, generated from the listings beside them by `docs_screenshots`, and a `breakout_art` setup so the ones that load artwork load the example's own. The character game's wall cannot be photographed -- the screenshot host omits the text layer on purpose -- so it is shown as compared output instead. `docs/07-sound.md` never said `SOUND`'s frequency is a SID register value rather than hertz, which both games depend on. It says so now, with the conversion from `src/audio_tables.c:84`. `TODO.md` gains the thirteen defects the two games turned up -- §6 items 30 to 33 and all of §9 -- each with a reduction that fits on a screen, the file and line of the cause, and what a fix would touch. Verified: `docs_examples` passes in both build configurations, `docs_screenshots --check` re-renders all thirteen figures and byte-compares them, the full 109-test suite passes in both builds, every quoted fragment was checked to appear verbatim in the listing it came from, and every relative link and anchor resolves. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 22:54:42 -04:00
Andrew Kesterson	6273be580a	Refuse a branch to a line the program did not number ... GOTO 100 in a script written without line numbers finds the hundredth line and branches there. Silent, plausible and wrong: the test for it loops forever printing the second line when the check is removed. akbasic_runtime_check_targets() is a fourth prescan beside the label, DATA and TYPE ones, run on every entry into MODE_RUN -- the earliest the check can be made and the only place all four ways a program arrives pass through. A target naming an empty line is still allowed, for the same reason RENUMBER leaves one alone, and a fully numbered program is unaffected, which is every program that existed before this. It shares RENUMBER's walk rather than repeating it. renumber.c grows an akbasic_TargetWalk -- a self pointer and a visit function -- and rewrite_line() takes one. RENUMBER's visitor substitutes the number a line moved to; the check's substitutes the number unchanged and raises. One walk, so the two cannot disagree about what a branch target is. The check points environment->lineno at the line being walked so the "? N :" prefix names the offending line. The other three prescans do not and report whichever line the loader stopped on; TODO.md section 5 item 64 records it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 16:38:54 -04:00
Andrew Kesterson	8bc253ebbf	Give a loaded line a number when it arrives without one ... A script written against LABEL and GOTO NAME never names a line number, so the numbers it had to carry were decoration. akbasic_runtime_load(), RUNSTREAM and DLOAD now file an unnumbered line one slot after the last one filed; a numbered line is filed under its number and moves the cursor, so the two mix. akbasic_runtime_file_line() is the one implementation of that rule, so the three paths cannot drift. The prompt is untouched. A line typed without a number is still direct mode and still runs now -- that is the only thing separating program text from a statement at a REPL, and it is why this is a loading feature. What this replaces was silent data loss: an unnumbered line was filed under the cursor unchanged, on top of the line before it. A blank line therefore erased whatever preceded it, and RUNSTREAM did not skip blank lines the way the other two paths did. That moves one golden file, and the reference had the same defect. language/arithmetic/integer.bas has four PRINT statements, an expectation with three values, and a trailing blank line that erased 40 PRINT 4 - 2 before the program ran. The expectation is now 4 4 2 2. tests/reference/README.md records the divergence and TODO.md section 5 item 63 says why. akbasic_SourceLine grows a `numbered` flag so an assigned number can be told from a written one. RENUMBER sets it on every line it touches; NEW, DELETE and DLOAD clear it. hadlinenumber moves to akbasic_scanner_scan(), so it always describes the line just scanned rather than only the REPL's. Two lines carrying the same written number still keep the last, as they always have. That is a separate decision. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 16:33:27 -04:00
Andrew Kesterson	d2ae0d75de	File the scanned line in RUNSTREAM, not the raw one ... process_line_runstream() chose between the stripped line and the raw buffer on obj->mode == AKBASIC_MODE_REPL, but nothing reaches that function except the RUNSTREAM arm of step(). The stripped branch was dead, so every program the driver ran from a file was stored with its own line number inside source[]: LIST printed "10 10 PRINT", and DSAVE and HELP would have echoed it the same way. No .bas in either corpus calls LIST, and runtime_verbs.c's load() helper -- which claims to load "the way RUNSTREAM would" -- already stored the scanned line, so it encoded the correct contract and could not catch the wrong one. The new test drives the real sink path instead. Keep the step-over-a-leading-number allowance in scan_line_labels() and skip_lineno(): no path inside the library stores a raw line now, but akbasic_runtime_store_line() is public and a host may hand it one. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 16:25:05 -04:00
Andrew Kesterson	812d846e47	Take libakgl 0.7.0, and refuse an over-long type or field name ... 0.6.0 and 0.7.0 break nothing here: 0.6.0 is three arcade-physics fixes and a physics.max_timestep property this port does not use, and 0.7.0 reports failures libakstdlib's wrappers were already catching and takes libakerror 2.0.1 so it can drop the exit-status trap its own suites needed. That is the same defect include/akbasic/error.h guards for this band, now fixed at the source rather than worked around in two places. The floor moves to 0.7.0 anyway. The soname carries MAJOR.MINOR while the major is 0, so deciding for ourselves which of libakgl's minor releases were really compatible is exactly the judgement it exists to take away. 0.7.0 is largely about a defect class worth checking for here rather than assuming past: ten unterminated strncpy calls into fixed-width name fields. Ours are clean -- every one is bounded to size - 1 and every buffer is either explicitly terminated afterwards or memset first, checked site by site. But two of them, both written last week in src/structtype.c, truncated an over-long name silently, and truncation is an error everywhere else in this interpreter. It matters more for a name than for a value: two long type names trimmed to the same 31 characters collide, and the second is then reported as redeclaring a type the program never wrote. Both are refused now, showing the name as written. The check was unreachable as first drafted, because the prescan read words into a buffer the size of the limit and so trimmed them before anything could look -- the scratch is twice the limit now, which is what makes the two cases distinguishable at all. tests/struct_types.c pins that it stays reachable. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 13:30:35 -04:00
Andrew Kesterson	c1d06ee4b8	Let DEF take structure parameters, and give call scopes back ... DEF AREA(S@ AS RECT) = S@.W# * S@.H# DEF POKEIT(P@ AS PTR TO RECT) A parameter names its type, exactly as DIM does. A bare `DEF F(S@)` is refused: @ says "a structure" without saying which, so it does not state a contract the way S$ does, and accepting it would mean checking fields at the call rather than at the declaration -- which is the hole naming the type closes. The cost is that there are no generic functions, and that is a real loss rather than an oversight. Passing is by value, because a parameter is bound by assignment and assignment copies; a pointer parameter copies its reference and lets a function change its caller's record on purpose. Neither is a special rule. What a structure parameter does need is its storage prepared before the copy, since a structure variable is a run of slots and there is nothing to copy into until the run exists. A DEF parameter list is no longer parsed as an argument list, because a parameter is a declaration rather than an expression: `S@ AS RECT` stopped that parser dead with "Unbalanced parenthesis". akbasic_value_is_truthy() learned that a pointer is true when it points at something, which had to come with this. Without it there is no way to test for the end of a list at all -- comparing a pointer to 0 reads a numeric field it does not carry and answers whatever that field held. A structure is deliberately given no truth value: it always exists, so the question has no answer worth guessing at. And a regression I introduced last commit, plus the older one underneath it. prev_environment() released a scope but not the variables the scope created, so a call leaked one slot per parameter and two hundred calls exhausted the 128-slot pool. Giving each DEF call its own scope made that reachable; it was there for GOSUB all along, measured on a stashed build -- a subroutine with a local of its own failed after about 128 calls before any of this work. The release is safe because a scope's table holds only what it created, and it is the variable slot that comes back rather than its storage, so a pointer into a record DIMmed in that scope stays sound. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 13:05:32 -04:00
Andrew Kesterson	00daa17a47	Give each DEF call its own environment, so recursion returns ... The function's environment was owned by the funcdef and re-initialised on every call, which made a function not re-entrant and cost two silent defects: DEF DBL(N#) = N# * 2 PRINT DBL(10) + DBL(1) was 4, should be 22 The result was a pointer into the funcdef's own environment, so the second call overwrote the first before the operator saw it -- both operands became the last call's answer. Two *different* functions in one expression were fine, which is most of why it was invisible. DEF FACT(N#) IF N# <= 1 THEN RETURN 1 RETURN N# * FACT(N# - 1) PRINT FACT(5) never returned The recursive call re-initialised the environment the outer call was still using, so the loop waiting for control to come back could not see it. No error, no bound, no diagnostic -- the one place in this interpreter that looped forever rather than raising. A call takes an environment from the pool now, exactly as GOSUB does. The result is copied into a caller-scope scratch before that environment goes back, because handing back a pointer into the callee is what made two calls collide and would now be a pointer into a released slot as well. RETURN parks its result on the *parent* rather than on the environment it is about to release, so nothing reads a freed slot to find it. Recursion depth answers to AKBASIC_MAX_ENVIRONMENTS like every other nesting, so too deep is "Environment pool exhausted" -- a diagnosis where there was none. akbasic_FunctionDef.environment goes with it, as dead state. One thing this exposed but did not cause, measured against a stashed build and recorded rather than fixed: a statement containing a failed multi-line DEF call still completes and prints a junk value. It is visible more often now only because runaway recursion reaches it where it used to hang. tests/language/functions/recursion.bas deliberately does not pin that answer. Chapter 16 loses its "walk a list with a loop, not a recursive DEF" caveat and gains the one that is still true: a function cannot take a structure parameter yet, so it reaches a record by name. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 12:29:35 -04:00
Andrew Kesterson	631c70ce7d	Share a host program's own C structures with a script ... A BASIC TYPE and a host C struct are the same thing seen from two sides, so both go in one type table and everything the language already does with a structure works across the boundary with no second set of rules. The host describes its struct once as a table of field descriptors and binds an instance: akbasic_host_bind(&SCRIPT, "FOE@", "ENEMY", &GOBLIN); after which `FOE@.HP# = FOE@.HP# - 10` decrements GOBLIN.hp in place, with no marshalling step the host has to remember to run. The sharing is done with shadow slots: a binding takes a run from the same value pool a DIMmed record uses, a field read refreshes its slot from host memory first, and a write converts back and stores. So the script always sees current values and its writes always land, while the rest of the interpreter goes on seeing one storage model instead of two. AKBASIC_HOST_FIELD takes the offset and the width from the same member, which is the only reason it is a macro: writing offsetof and sizeof out by hand is two chances to name the wrong member and no way to notice. A field name's suffix must agree with the C type it describes, refused at registration -- a host writing "HP%" over an int32_t has said two different things about one field and the script would believe the suffix. Conversion refuses rather than truncates. 200 into an int8_t, 70000 into an int16_t, -1 into a uint8_t and thirteen characters into a char[8] are each an error naming the field, because a silent wrap is found three frames later in code that did nothing wrong. Each width is tested separately, since a range check is exactly the thing that is right for int32_t and wrong for int8_t when only one of them is covered. The language's own distinction turns out to be the one a host needs, so there is one API rather than two: assignment copies and gives a script a private snapshot, POINT shares and lets it change the game, and which one happened is visible in the listing. Two things the work required. The prescan runs again on every RUN and used to wipe the whole type table, unregistering the host's types the first time a script ran; it now keeps what the host registered and drops only what the script declared. And akbasic_runtime_start() did not rewind, which cost nothing while a host started a script once and cost everything to a host running one per enemy -- the second start began past the end and silently did nothing. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 11:56:04 -04:00
Andrew Kesterson	2a3f68d2c4	Add strict pointers: AS PTR TO, POINT ... AT, and the -> operator ... A pointer is a distinct declared kind rather than a mode a structure can be in, which is what "strict" means here: `.` requires a structure on its left and `->` requires a pointer, neither stands in for the other, and both refusals name the operator the program should have used. So a reader always knows from the spelling whether the thing on the left is their own copy or somebody else's data. Assignment still copies. POINT is the only way to share, so a program that never writes it can never be surprised by aliasing -- and `P@ = A@` is refused with a message saying to POINT it instead, rather than quietly becoming the one assignment in the language that does not copy. PTR TO is also the only way a TYPE may refer to itself, since by value it would have no finite size. That is what makes a linked list possible, and tests/language/structures/pointers.bas builds one, walks it and renders it. Rendering follows pointers, so it needs a depth bound where copying does not: copy stops at a pointer by construction, but two nodes pointing at each other is easy to write and PRINT would not come back. Four levels, chosen so the bound bites before the 256-byte render buffer does -- otherwise a cycle would stop because it ran out of room rather than because it was told to. Three things the work turned up, all now pinned by tests: A freshly DIMmed record printed `(UNDEFINED STRING REPRESENTATION FOR 0)` for every field. Slots now take the type their field declared, so it reads as zeros. Adding POINT as a verb makes POINT unusable as a type name, and the parser reported that as "Expected expression or literal" pointing at the line rather than the problem. The prescan now refuses a reserved word as a type name and says so. Field names follow the same reserved-word rule as variable names, enforced by the loader's own scan -- `TO@` is a bad field name for exactly the reason `TO#` is a bad variable name. Recorded rather than worked around. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 11:48:09 -04:00
Andrew Kesterson	6a7c8cd920	Add records: TYPE, DIM ... AS, field access, copy on assign ... BASIC 7.0 has no records at all, so none of this is a port. The `@` suffix was not invented either: the Go reference reserved IDENTIFIER_STRUCT and never used it, and src/grammar.c rendered such a leaf as "NOT IMPLEMENTED" until now. Declaring the type is what buys the storage model. A TYPE states its fields, so an instance has a known slot count and is laid out exactly as an array is -- one contiguous run from the same value pool DIM already draws from, with field access as offset arithmetic. No new pool holds data; the only new table holds descriptors. A nested value flattens into its container's run, which is why LINE with two POINTs and a string is five slots rather than three. Each field takes its type from its own suffix, the same rule every other name here follows, so a field list needs no type column. An `@` field is the exception and has to name its type, because three primitive types fit in three suffix characters and N declared types do not fit in one. The declaration is prescanned before the program runs, like labels and DATA and for the same reason: it has to be in effect wherever control goes. Three passes, each for a case the one before cannot do -- names first so a field can refer to a type declared later, then field lists, then sizes by repeated resolution. What never resolves is a cycle of by-value containment, so "a TYPE cannot contain itself by value" is a diagnosis rather than an assumption, and the message says to use PTR TO instead. Assignment copies. That interception is the whole feature and it cannot live in akbasic_value_clone(), which copies one slot -- and one slot holds a *reference* to an instance rather than the instance, so going through it would alias. A structure is intercepted before that path and its slots are copied one at a time, walking the descriptor rather than memcpy-ing the run, because a pointer field must copy its reference where a value field must copy its slots. Two smaller things the work required. All three prescans now sit inside one ATTEMPT: a malformed declaration is the program's mistake, and it was printing a stack trace and taking the driver with it, which is the boundary goal 3 exists to draw. And a fresh variable's structtype is -1 rather than the 0 a memset leaves, because 0 is a valid type index and every new variable was claiming to be the first type declared. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 11:39:47 -04:00
Andrew Kesterson	8117fb564d	Refuse an operand the numeric path cannot read ... math_minus, math_multiply and math_divide were `if ( INTEGER ) ... else <treat as float>`, and that else was a catch-all rather than a float branch: it read floatval from whatever it was handed. A truth value keeps its payload in boolvalue and leaves floatval zero, so a truth value on the left computed into a field nothing reads and kept its BOOLEAN type -- (A# == 1) - 1 printed true, should be -2 (A# == 1) * 3 printed true, should be -3 (A# == 1) + 1 correctly refused wrong in value and in type, and silent. math_plus escaped only because it enumerates its cases and ends in an error. The three now share one require_numeric() guard, so a type added later is refused by all of them at once instead of quietly taking the float branch in each. The two operands have different rules and that asymmetry is the point: the left one picks the branch and must be a number, while the right is read through rval_as_int(), which handles -1/0 deliberately. `5 - (A# == 1)` is 6, and that is the same property that lets AND and OR double as logical operators, so refusing a truth value on the right would have broken every condition in the language. Found by asking what a structure operand would do to this path, which is where AKBASIC_TYPE_STRUCT is about to arrive. The structures work did not create the defect; it made an already-reachable one worth chasing. Two stale comments went with it. src/value.c's header and a duplicate block above rval_as_int both cited "TODO.md section 12", which does not exist -- the defect list is section 6 -- and the duplicate described the summing behaviour item 5 had already removed. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 11:22:50 -04:00
Andrew Kesterson	3415c9aec6	Take libakgl 0.5.0 and rename every symbol it namespaced ... 0.5.0 gives every exported symbol the akgl_ prefix, which is the first libakgl release to break this project's source rather than only its ABI. The soname goes to libakgl.so.0.5 and include/akbasic/akgl.h asserts the floor. What moved here: akgl_render_bind2d is akgl_render_2d_bind, akgl_sprite_sheet_coords_for_frame is akgl_spritesheet_coords_for_frame, the renderer, camera and window globals carry the prefix, and _akgl_renderer and _akgl_camera are akgl_default_renderer and akgl_default_camera. The renames were applied by site rather than by pattern, because renderer is also a parameter name in src/sprite_akgl.c and a struct member throughout src/frontend_akgl.c -- a substitution would have rewritten both without a word. That is the same trap upstream describes hitting, and it is worth knowing that the defect behind the rename was not cosmetic: an exported global called renderer collided with a test's own variable, the executable's definition preempted the library's, and every texture load in that suite failed while the suite passed. 0.5.0 also fixes libakgl defect 26, which was one of the two reasons src/sprite_akgl.c installs its own renderfunc: akgl_actor_render took its destination height from the sprite's width, drawing a 24x21 Commodore sprite as a 24x24 square. The renderfunc stays, because the other reason has not moved -- an actor carries one scalar scale and SPRITE has separate x- and y-expand bits -- but the comments and TODO.md deviation 40 no longer claim a defect that is fixed. Every documentation figure re-renders byte-identical under the new library, which is what says the sprite and drawing paths did not move underneath them. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 08:01:43 -04:00
Andrew Kesterson	8077806598	Take libakerror 2.0.1, and guard the exit status it fixes ... 2.0.0 makes the error pool and the status registry thread safe, and it is an ABI break carrying the soname to libakerror.so.2. The break is a quiet one: __akerr_last_ignored became thread-local and akerr_next_error() now returns a context that already holds a reference, so objects compiled against a 1.x header and linked against 2.x count every reference twice and never give a slot back. Nothing about that fails to link, which is exactly what a guard is for -- include/akbasic/error.h feature-tests AKERR_THREAD_SAFE instead of AKERR_FIRST_CONSUMER_STATUS, which 2.0.0 also still defines and which therefore no longer distinguishes anything. 2.0.1 is the release this band needed most. The default unhandled-error handler ended in exit(errctx->status), and a process exit status is one byte: AKBASIC_ERR_BASE is 512, and 512 truncates to 0, so an unhandled AKBASIC_ERR_SYNTAX reported success to anything watching $?. Every other code in the band came out as some unrelated error's number. akerr_exit() substitutes 125 for anything a byte cannot carry, and a probe raising AKBASIC_ERR_DEVICE through FINISH_NORETURN now exits 125 rather than 7. It was latent here rather than live -- src/main.c handles the context and returns EXIT_FAILURE, and every test with a top-level ATTEMPT carries a HANDLE_DEFAULT -- but "no caller relies on it today" is not a property a header can keep true. tests/version_check.c asserts the mapping and fails if AKBASIC_ERR_BASE ever stops truncating to zero, because that is the day this stops being about our base. Chapter 10 gains a threading section: libakerror is safe from any thread now, and this interpreter is not and has no lock anywhere in it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 08:00:24 -04:00
Andrew Kesterson	16b38c1138	Generate the documentation's figures from the listings they illustrate ... Chapters 6 and 8 described what a verb draws in prose. Eight figures now show it, and each one is produced by running the BASIC listing printed immediately above it -- so a picture cannot drift away from the code beside it, which is the way a screenshot goes wrong and the way nothing notices. tools/screenshot.c is a second SDL host, much smaller than the frontend: dummy video driver, software renderer, run to completion, read the target back, write a PNG. It draws no text layer on purpose, so a READY in the corner is not noise in a figure about BOX and no font has to be resolved. tools/docs_screenshots.sh reads the new screenshot=NAME fence tag straight out of the markdown. size=WxH is the second tag, and SCALE's figure uses it: the point being made is a 320x200 listing filling a larger window, which cannot be made on a 320x200 surface. Two gates, answering different questions. docs_examples fails a tagged block with no image, in both configurations, so a figure cannot be added and forgotten. docs_screenshots -- a CTest, AKGL build only -- re-renders every figure and compares byte for byte, so a listing edited without regenerating fails. Only the second catches a stale picture. The PNGs are checked in because a reader on the forge has no build tree, and docs/images/README.md says loudly that they are generated. Regenerating is never part of a build: the target is run deliberately, so a make cannot put eight binary diffs in front of whoever ran it. Drawing the BOX figure caught a defect in TODO.md itself. Deviation 16 claimed in bold that BOX fills on a negative angle while its own paragraph said the fill was filed rather than implemented. BOX cannot fill, and filled_rect is reached by no verb as a result. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 07:37:04 -04:00
Andrew Kesterson	48f650c3af	Stop an armed TRAP from swallowing parse errors whole ... A program with TRAP set and a line that would not parse printed nothing at all and exited zero. No error line, because akbasic_runtime_error() intercepts for the trap and deliberately prints nothing; and no handler, because the parse branch of process_line_run() then set run_finished_mode regardless -- QUIT for a file -- so the next line boundary the handler would have been entered at never came. Arming an error handler made errors disappear. The guard is to set the finished mode only when the error was actually reported. The runtime path was always right: report_and_reraise() never touched the mode. The same branch also never recorded the status, so the handler that now runs was handed ER# 0. It sets lasterrorstatus from the context the way report_and_reraise() does, and a trapped SCALE with no arguments reports 512. Found while writing the error-code appendix -- documenting what ER# can hold means provoking each code, and this is what happened on the way. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 07:36:00 -04:00
Andrew Kesterson	5c5bf63356	Draw into the whole window, not its top-left 320x200 ... The graphics verbs documented a coordinate transform that did not exist. With SCALE off a coordinate went straight to akgl_draw_* as a pixel address, so an 800x600 window drew a C128 listing into its corner and left the rest unused -- while the chapter said coordinates were 320x200 and stretching to fit was the host's business. akbasic_GraphicsBackend gains a size entry point, require_graphics() asks it before every verb that draws so a resized window is honoured between two statements, and 320x200 becomes the fallback for a backend that leaves it NULL. It is the record's one optional member, so a host written against the old header keeps the behaviour it had. SCALE now maps onto the device, and RGR(1)/RGR(2) report the drawing surface so a program can use a window whose size it did not choose. RGR(0) is BASIC 7.0's own field, the GRAPHIC mode. SCALE also mapped xmax onto the width rather than onto the last pixel, so SCALE 1, 319, 199 followed by DRAW 1, 319, 199 drew nothing at all -- one pixel past the surface. Fixed in the same line, because it is what makes "SCALE gives a C128 listing the whole window" true rather than nearly true. The akgl test renders against a 128x128 target, deliberately smaller than the old constants: a SCALE still dividing by them misses it entirely rather than landing somewhere plausible. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 07:35:20 -04:00
Andrew Kesterson	23ccb66f69	Document the interpreter's architecture as chapter fourteen ... Chapters 1 through 13 describe the language. Nothing described the machine that runs it, and the answers were spread across header comments, TODO.md sections written for a different purpose, and the source itself. Somebody embedding the interpreter, debugging something it did, or adding a verb had to reconstruct the shape from all three. docs/14-architecture.md is that shape, and only that: the three targets and the driver, the single akbasic_Runtime and why nothing is file-scope, akbasic_runtime_step() unrolled with the reason each stage sits where it does, the four modes and what set_mode() does beyond assigning, a line's journey from text through tokens and leaves to a verb handler, the dispatch table, the pool map with what each exhaustion actually says, environments doubling as block state, the two kinds of error, devices, and interrupts. It defers rather than restates. The headers are the authority on every function's contract and the chapter says so up front; where a rule is subtle the header comment already states it at more length than a chapter should. MAINTENANCE.md keeps the conventions and now points here for the mechanism, so there is still one copy of each. Two sections are the reason it exists at all. Debugging: reading a TRON trace as evidence about the loop rather than the lines, reading an akerror stack trace and what it is not, four breakpoints and the expressions worth printing at them, narrowing with ctest -R and the mock devices, and a symptom-to-cause table. Changing it: the verb recipe end to end including the private src/verbs.h prototype that is easy to miss, the rule that a missing dependency capability gets filed upstream rather than worked around, and the five constraints goal 3 puts on any change. A `text` fence tag comes with it. Every fenced block in docs/ is executed and an untagged one is a hard error, so six block diagrams had nowhere to live. The tag means never executed, it is counted in the skip line like `cmake`, and MAINTENANCE.md documents it -- the alternative was an indented block the extractor never sees, and a picture nobody decided about is indistinguishable from a test nobody ran. tests/docs_examples.sh now makes --root and --basic absolute before it starts. Both are used from inside a sandbox directory it cd's into, so the invocation MAINTENANCE.md itself documents -- --root . --basic ./build/basic -- failed every example with "exited 127" and every setup= with "setup failed". CTest passes absolute paths and never saw it; running one document by hand hits it immediately. Writing the error section turned up a defect and TODO.md section 8 records it. The ATTEMPT blocks that turn a script's mistake into an error line wrap parsing and interpretation but not scanning, so a line with more than 32 tokens escapes as an interpreter error: stack trace, exit 1, and at a prompt the REPL is gone. That is the same shape as section 8 item 2, on a path that fix did not cover. Not fixed here -- it is a behaviour change and wants its own tests -- but written down with the three call sites and what would cover them. Both configurations stay green: 95/95 and 94/94. docs_examples now runs 37 programs, 9 transcripts, 45 output comparisons, 3 C snippets, 2 excerpts and 2 shell blocks, and skips 9 text blocks. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 23:14:17 -04:00
Andrew Kesterson	342e4c07da	Execute every documented example as a test ... docs/ and README.md carry 85 fenced blocks. Every one was checked by hand exactly once, when it was written, which is not a standard that survives a changing interpreter -- and four were already wrong: two transcripts showing a leading space PRINT does not emit, akbasic_TextSink in README.md missing the two members it had grown hours earlier, and FILTER's refusal quoted with wording the code does not use. tests/docs_examples.sh reads a fence-tag vocabulary and runs what it finds. BASIC programs and transcripts run and are byte-compared against an `output` block; C snippets compile with -fsyntax-only against the real include path, which CMake writes out because it is transitive through akerror, akstdlib and akgl; shell blocks run in a sandbox. Anything that would reconfigure the build tree, hit the network or re-enter the suite is tagged norun with the reason in MAINTENANCE.md, and the two cmake blocks stay hand-maintained by decision. An untagged block is a failure rather than a default, and the pass line reports what it executed by kind. Both exist because the way a harness like this dies is by quietly matching nothing and passing -- which it duly did on the first CTest run, where a generator expression evaluating to nothing still contributed an empty argument that the script read as a filename. The count is what caught it. The excerpt check earns its own mention: a block tagged `c excerpt=include/akbasic/sink.h` must still appear in that header, comments and whitespace ignored. Compiling it would only redefine the type, so a compile check could not have found the stale struct, and did not. Registered as the CTest case docs_examples in both configurations. Fixing the four wrong examples turned up two interpreter defects, fixed in the previous commit and recorded in TODO.md section 8. MAINTENANCE.md is new: the fence-tag reference, what to do when the case fails, and the conventions that until now only existed inside source comments -- the three test lists and how two of them invert "passed", the sorted verb table, that a golden file is never edited to suit this interpreter, and that a fix gets mutation-checked with a file copy rather than git checkout. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 22:41:36 -04:00
Andrew Kesterson	6f49f6a7f2	Stop DLOAD eating a line, and a prompt error killing the driver ... Two defects that the same mechanism produced, both found by making the examples in docs/ actually run. DLOAD scans the file it reads through the runtime's own scanner, so by the time it returns, the tokens of the line that invoked it are gone and hadlinenumber and environment->lineno describe the last line of the *file*. The REPL carried on parsing what it believed was still its own buffer, concluded the leftovers were program text because hadlinenumber was now true, and filed the DLOAD command itself under that line number -- silently replacing the last line of every program loaded from a prompt. It now abandons the rest of the line, which is the only thing that can sensibly follow replacing the whole program. The second is the same class of oversight one layer up. process_line_run() has always swallowed the error context after interpret() puts the BASIC-level line on the sink, with a comment saying that is what goal 3 requires. The direct-mode branch of process_line_repl() used a bare PASS instead, so `VERIFY` against a file that did not match -- an ordinary user answer, not a fault -- came back as a stack trace and terminated the driver. An embedding host would have gone with it. Both tests fail when their fix is reverted. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 22:41:19 -04:00
Andrew Kesterson	9845e77a5c	Finish the language: every remaining verb group, and the defects that blocked them ... Closes groups A, C, D, E, F, H and J of TODO.md section 4, plus RESTORE and RENUMBER, and closes section 6 -- all seventeen reference defects. Seven of those turned out to have been fixed or never ported and nobody had written it down; the audit records the evidence for each. Two of the seventeen were real. math_plus mutated its left operand when the operand was mutable, so A# + 1 could modify A#; it was gated on FOR/NEXT coverage because NEXT relied on the mutation, so tests/for_next.c came first and NEXT now writes the counter back itself. And the binary operators summed both numeric fields of their right operand, which no BASIC program can reach -- that one needed a test written against the value API. Writing the tests turned up eight defects nobody had listed. Seven are fixed: IF A = 2 THEN was a parse error; only == worked IF ... AND ... was a parse error, because a condition parsed as one relation IF A = 1 OR B = 2 THEN was silently always false, and so was IF A THEN EXIT before any NEXT restarted the program and exhausted the variable pool READ never found a DATA line above it, and swallowed the lines between PRINT 2 + 2 at the prompt was filed as program text instead of answering a short read discarded its bytes, so COPY produced empty files every verb taking an argument list said "peek() returned nil token!" on none The eighth is not fixed and cannot be quietly: a FOR whose step overshoots runs its body one extra time, and FOR I = 1 TO 1 runs it zero times. The two errors cancel for a step of 1, which is why neither was noticed. Correcting them changes the expected output of a checked-in acceptance file, and tests/reference/README.md forbids editing one to suit this interpreter. It is tests/for_semantics.c in AKBASIC_KNOWN_FAILING_TESTS, asserting the correct contract, and TODO.md items 19 and 20. Sprites are real libakgl actors with a renderfunc of their own, because akgl_actor_render draws every sprite square and an actor has no per-axis scale. Both are filed upstream. SPRSAV takes an image file, an SSHAPE handle or a 63-element integer array -- a string here cannot hold a zero byte. Verbs that need hardware that does not exist are refused by name with the reason rather than faked: SYS, HEADER, COLLECT, BACKUP, BOOT, FILTER, and DIRECTORY, which is refused for a missing libakstdlib wrapper filed upstream. 94 tests in the default build, 93 with SDL, 94 under ASan and UBSan, doxygen clean. The Go acceptance corpus stayed green throughout. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 21:50:37 -04:00
Andrew Kesterson	df50201121	Own every pixel each frame, and bring the cursor back as a blinking block ... The blinking backspace was not the backspace. The sink skipped rows it believed were already clear, tracked in a drawn[] array, which assumes a frame inherits the frame before it. SDL_RenderPresent swaps buffers, so a frame inherits the one two back: a row erased once is clean in one buffer and dirty in the other, and presenting alternates between them. The first character of a backspaced wrap flickered forever. It reproduces on X11 and never under the dummy driver or a software renderer, which is why the suite stayed green through two rounds of fixing it. The sink now repaints every row it owns every frame -- a frame either owns every pixel it presents or inherits pixels it cannot reason about. Confirmed on real hardware with the reported input: the wrapped tail's row reads zero across five successive captures. The cursor returns as a blinking block, half a second per cycle, off SDL's clock. It sits in the cell after the text rather than under it, which is what made the underscore unreadable, and it wraps to the next row when a line exactly fills one -- where the next character actually lands. The new regression test paints stale pixels by hand, which is what a swapped-in buffer hands back, so the case is covered without real hardware. Every new assertion was checked by reverting the fix and watching it fail. Recorded honestly in TODO.md section 5: the same buffer swap means the graphics verbs were never reliable across frames either. A one-shot DRAW lands in one buffer and the next present shows the other. Making that work needs a persistent surface, which is its own commit. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 15:23:41 -04:00
Andrew Kesterson	acd20eed9a	Erase what the text layer drew: three GUI bugs, one cause ... The sink painted glyphs on top of whatever was already on the renderer and never erased anything, and the host deliberately does not clear the frame so a DRAW survives. The grid was always correct; the screen kept the previous frame. That surfaced as three separate-looking faults: - a backspaced character stayed on screen, including across a line wrap - a scroll left the old rows behind, "papered over with garbage" - the editing cursor smeared an underscore along every column it passed through, which read as an underline under the text being typed render() now fills each row it is about to draw, and each row that has emptied since it last drew, with the background first. Row by row rather than one clear over the whole area: the text layer is authoritative over the rows it occupies and leaves every other pixel alone, so a picture behind the text loses only the strips the text uses instead of all of it. echo_line() also truncates rows that hold nothing but the spaces its own erase pass wrote, which is what backspacing back across a wrap leaves behind. A row of spaces is text as far as render() is concerned, so it would have been repainted forever and kept erasing whatever was under it. The cursor glyph is removed outright, as asked. The smearing was the erase bug rather than the cursor, so one could come back and behave -- a block would read better than an underscore. Four pixel-level tests, because grid assertions could never have caught any of this. Each was checked by reverting the fix and watching it fail; two of them were vacuous when first written and are noted as such where they are fixed. The real-keyboard test also now rubs out a character and scrolls forty lines. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 15:03:37 -04:00
Andrew Kesterson	cfdde907df	Type at the window with a real keyboard: the akgl_typing test ... xdotool closes the gap that shipped the missing SDL_StartTextInput(). Every other keyboard test synthesises SDL events, which covers the code downstream of SDL and cannot cover the code upstream of it -- so the suite stayed green while the real keyboard was dead. akgl_typing starts the driver under a pty, waits for the window with xdotool search --sync, gives it focus, and types a program containing a string literal and a lower-case one, polling the mirrored stdout for what they print. Verified by reverting both halves of the text-input fix and watching it fail with the reported symptom: READY, and nothing after it. Skips rather than fails without a display, xdotool, script(1) or a window manager -- none of those means the answer is no. It steals keyboard focus for about fifteen seconds; AKBASIC_SKIP_INTERACTIVE=1 skips it deliberately. xdotool and script(1) are documented as optional test dependencies, alongside what gcovr and python3 already bought. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 14:35:07 -04:00
Andrew Kesterson	024a33dbba	Start SDL text input: the AKGL build's keyboard was dead ... SDL3 has text input off by default and per-window, so without SDL_StartTextInput() it emits no SDL_EVENT_TEXT_INPUT at all and every keystroke reaches libakgl's ring with an empty text field. The editor had just been changed to prefer that composed text over the keycode, so it read every key as not-a-character: no echo in the window, and nothing on stdout either, because RUN could never be typed. One cause, both symptoms. The editor now falls back to the keycode when there is no composed text, so a host that forgets to start text input gets a worse keyboard rather than none. The suite missed this because every keyboard test pushes the text-input event into SDL's queue by hand -- which is what a real keyboard produces, but only once text input has been started. Synthesising the end of a chain cannot test the beginning of it. The new test asserts SDL_TextInputActive() directly, and both halves were checked by reverting each and watching it fail. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 14:23:07 -04:00
Andrew Kesterson	fca9ad4a89	Consume libakgl 0.3.0: every workaround deleted, two capabilities gained ... 0.3.0 closed all ten API gaps this port had filed. The four workarounds go with them: the CMake block that declared libakgl's vendored dependencies by hand, the akgl/actor.h include in three files, and the six vtable pointers assigned by hand in two more, now akgl_render_bind2d(). Two gaps were capabilities rather than inconveniences, and both are now real: The line editor takes the composed UTF-8 text the ring carries in preference to the keycode, so shifted characters, keyboard layouts, compose keys and dead keys all work. A double quote can be typed, which means a BASIC string literal can be typed -- the sharp end of the old limitation. Letters are no longer folded to upper case. SOUND's dir/min/step reach akgl_audio_sweep instead of being refused. dir 3 sweeps once rather than oscillating and TODO.md section 5 says so. A backend with no sweep still refuses the swept note and plays the held one. The adaptors now carry an AKGL_VERSION_AT_LEAST(0, 3, 0) floor, verified by temporarily demanding 0.4.0 and watching it fire. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 13:25:14 -04:00
Andrew Kesterson	583c0abbd2	Retire the byte-for-byte fidelity constraint, and fix what it was blocking ... The Go reference is deprecated and will not be updated, so the two projects are no longer required to match. Recorded as TODO.md section 0.1, first thing in the file, because it silently reverses the premise several later sections were written on -- an agent reading section 6 without it will park work that is no longer blocked. Section 6 item 16 was the item waiting on exactly this and is now fixed: the keyword tables are searched on the base name with any type suffix stripped, so PRINT$, LEN# and GOTO% are refused as variable names and the reference's own diagnostic stops being dead code. It cost the one golden case predicted, and the cost was nothing -- renaming a variable in strreverse.bas left its expected output byte-for-byte unchanged. AKBASIC_KNOWN_FAILING_TESTS is empty as a result and known_reference_defects.c is gone. Section 6 items 1-9 and 11 are reopened as an ordinary defect list. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 12:52:00 -04:00
Andrew Kesterson	eb5374d212	Check the reference corpus in, so the build stops needing the Go submodule ... All 41 .bas/.txt pairs copied byte for byte from basicinterpreter@d76162c into tests/reference/, plus the Commodore font into assets/fonts/ -- the two things that tied the build to deps/basicinterpret. Both were verified cmp-identical to the submodule copies. This reverses a decision that was deliberate and correct at the time: the corpus was driven in place because copying a submodule's corpus guarantees drift. Overruled on purpose -- the Go dependency is being deprecated, and a build that cannot run its acceptance suite without cloning the implementation it replaced is not finished. tests/reference/README.md records what the drift now costs and that those expectations are never edited. Checked rather than assumed: both configurations configure, build and pass from scratch with deps/basicinterpret moved out of the tree entirely. The submodule is kept as the behavioural spec, which is a real use. The font came with an open licence question; assets/fonts/PROVENANCE.md states it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 12:35:40 -04:00
Andrew Kesterson	bfac13ff87	Implement the housekeeping verbs, and stop the REPL spinning after an error ... NEW, CLR, CONT, SWAP, TRON, TROFF and HELP. None is in the Go reference, so what each means here is recorded beside it. Testing CONT turned up a hang that predates this: the runtime's error class is deliberately sticky, and with run_finished_mode REPL every later step re-entered REPL and printed READY -- overwriting the QUIT that end of input had just set. An interactive session that hit one runtime error printed READY forever instead of exiting. RESTORE and RENUMBER are deferred with reasons; RESTORE turns out to need a DATA pointer this port does not have, which is a defect in its own right. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 12:07:50 -04:00
Andrew Kesterson	f4007d80d4	Give argument lists their own link, not each argument's .right ... An identifier's subscript list, a unary's operand and a binary's right-hand side all lived in the same field the argument chain used, so ABS(-9), MOD(A#, B# + 12) and any array reference in a parameter list were counted as extra arguments and refused. Subscript lists move to .expr and arguments now chain through a dedicated .next. This is the third time the same collision was fixed; the first two moved it along rather than removing it. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 11:58:15 -04:00
Andrew Kesterson	5b7b7d2ed9	Add akbasic_runtime_global: a host variable lands in the script's root scope ... A host creating a variable while a script was suspended got it in whatever scope was active -- usually a FOR or GOSUB body -- and it died when the body popped, silently. Reaching for the root by hand returned NULL without raising, because environment_get only auto-creates in the active environment. Both are still true of environment_get, which is correct for what the interpreter uses it for. The README and the example now point somewhere else. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 11:53:05 -04:00
Andrew Kesterson	a31058cf37	Consume the COLON token: a line can hold several statements ... The token has existed since the scanner was written and nothing read it, so 10 PRINT A$ : REM ... was a parse error. Leading separators are consumed before each statement and an empty statement yields a NULL leaf rather than an error, so a trailing colon and a run of them are both legal. BASIC 7.0 scopes everything after THEN to the condition, which the reference had no opinion about because it never got here. The rule is not "skip when false": the rest of the line belongs to whichever arm was written last. A whole FOR/NEXT on one line still does not loop -- block skipping works by source line. Recorded in TODO.md as what group A has to fix first. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 11:46:10 -04:00
Andrew Kesterson	0f3d8a0ac6	Close the value.c mutation survivors, and correct one that cannot be ... Two new tests in value_arithmetic.c, each verified by hand-applying the mutant rather than by assuming. The obvious maximum-length-string test does not work: math_plus clones self into the scratch first, so joining a full string to an empty one leaves the byte a short copy missed already correct. The operands have to sum to the limit without either being the answer. One of the five listed survivors is equivalent and cannot be killed. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 11:38:45 -04:00
Andrew Kesterson	1eb8f9ffaa	Fix five defects the port uncovered in the reference parser and scanner ... Chained subtraction and exponentiation fold left instead of abandoning the rest of the line -- `1 - 2 - 3` gave -1 and dropped the `- 3`. A unary leaf's operand moves to .left, so a negative literal is one argument again and a second argument no longer overwrites it. An operator in a line's final column survives. Hex literals reach the parser whole. A leading zero is padding, not a radix. Item 16 stays pinned: the fix works and costs an upstream golden case, which is a decision rather than a defect. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 11:35:14 -04:00
Andrew Kesterson	f24201fdef	Port the standalone SDL frontend, and give the sink a line editor ... An AKGL build of `basic` was a terminal program with unused SDL linked into it. It now opens the reference's 800x600 window, draws BASIC output in the Commodore font, pumps events, lets you type at it, and still mirrors every byte to stdout. The stdout mirror is a composing sink rather than a second write inside the interpreter, and lives in the core library where it needs no SDL. The line editor waits for a typed line by borrowing one frame at a time from the host, so nothing blocks and nothing owns an event loop it should not. The whole golden corpus now runs through the SDL binary as well as the stdio one, byte for byte. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 11:21:39 -04:00
Andrew Kesterson	ecdc6b60ef	Delete src/convert.c: libakstdlib 0.2.0 grew the contract it existed for ... That file wrapped strtoll and strtod because libakstdlib's aksl_ato* family could not report a conversion failure at all -- atoi("not a number") returned success with 0, turning four diagnosable errors into wrong answers. Its own note said what to do when that changed: "When it grows it, delete src/convert.c and switch the call sites over." 0.2.0 grew it, so it is gone. Six call sites go straight to the library now: both literal constructors in src/grammar.c, the line number in src/scanner.c, FunctionVAL in src/runtime_functions.c, INPUT in src/runtime_commands.c, and GSHAPE's handle in src/runtime_graphics.c. aksl_strtoll(str, NULL, base, &dest) rather than aksl_atoll wherever a base is involved, because the ato* forms are base 10 and grammar.c picks base 8 or 16 off the lexeme's prefix; the NULL endptr is what makes trailing junk an error rather than a stopping point. The raised status changed from AKBASIC_ERR_VALUE to AKERR_VALUE, and the message with it -- VAL("garbage") now says `no digits in "garbage"`. Section 1.8 makes message text part of the acceptance contract, so that was checked against the corpus before touching anything: no golden file contained a conversion message, which is also why section 1.9 had been asking for one. Two exist now, so the next change to that text has to move a golden file, and one of them pins the reference's octal-literal defect (section 6 item 10) while it is still deliberately reproduced. tests/convert.c became tests/numeric_contract.c rather than being deleted with the code. The assertions did not stop being worth making when the wrapper went away -- they became assertions about a contract this port depends on and no longer owns, and a regression in it would make four things quietly return zero. Repoints the CI mutation job, which was bounded to src/convert.c and src/symtab.c. src/symtab.c alone measures 74.1% against the gate of 65. src/audio_tables.c was measured as a replacement second file and scored 64.7%: that is a real gap rather than a reason to skip it, since almost every survivor is in akbasic_audio_state_init, where nothing asserts a freshly initialised audio state is actually zeroed -- the same gap this job's history records closing for symtab. Recorded in TODO.md so the file can earn its place back. One thing worth knowing before reading any score here, and now written down: the harness's ICR operator only rewrites the constants 0 and 1, so a lookup table of other values produces no mutants and a high score over one says nothing about whether its entries are right. tests/audio_verbs.c now asserts all 32 ADSR entries against the datasheet anyway, because a hand-edit typo is the real failure mode there -- but that could not and did not move the mutation number, and claiming otherwise would be the kind of thing this file exists to stop. 72/72 core, 73/73 with libakgl, 72/72 under ASan+UBSan, coverage 93.6% line and 97.8% function, clean under -Wall -Wextra, doxygen clean. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 10:28:04 -04:00
Andrew Kesterson	4fc763efb3	Wire the sink and the three devices to libakgl ... src/sink_akgl.c, src/graphics_akgl.c, src/audio_akgl.c and src/input_akgl.c, in the akbasic_akgl target, which is the only thing here that links SDL. -DAKBASIC_WITH_AKGL=ON had never been configured in this repository before, and it now builds and passes. The sink is what section 3 has been waiting on. Its character grid comes from akgl_text_measure(font, "A", &w, &h), the direct equivalent of the reference's font.SizeUTF8("A") and the call that did not exist until 42b60f7. Wrapping is done on the character grid rather than by handing SDL_ttf a wraplength, because the cursor has to land somewhere definite: a program that PRINTs a long string and then PRINTs again expects the second to start on the row after the first ended, and only the code that placed the characters knows which row that is. tests/akgl_backends.c draws into a 128x128 software renderer under the dummy video driver and reads the pixels back -- the pattern deps/libakgl/tests/draw.c established, which needs no display and no offscreen harness. It asserts the seam rather than libakgl's own behaviour: a BASIC line in, a lit pixel of the right colour out. Four things in libakgl had to be worked around to get here. All four are commented at their site with "filed upstream" and recorded in TODO.md section 3: - An embedded libakgl requires SDL, SDL_image, SDL_mixer, SDL_ttf and jansson to be *installed*. It builds its own vendored copies only when it is top-level, and they are sitting right there in deps/libakgl/deps. Every lookup is guarded with if(NOT TARGET ...), so this adds those five subdirectories before add_subdirectory(deps/libakgl) -- the same trick and the same ordering requirement akerror::akerror and akstdlib::akstdlib already need. - akgl/controller.h does not compile on its own: it declares handlers taking an akgl_Actor * and includes nothing that declares the type. - There is no way to attach a 2D backend to a renderer you already have. akgl_render_init2d() installs the vtable but also creates its own window and writes the camera global, so it belongs to the akgl_game_init() path -- which is exactly the path an embedding host is not on. The test assigns the six pointers by hand. - akgl_text_rendertextat() segfaults on a backend whose vtable is empty; it reaches through renderer->draw_texture without checking it. Same class of defect 42b60f7's own commit added a draw test for. The sink's readline reports end of input rather than reading: a drawn text layer is not a source of lines, and INPUT through one wants a line editor built on the keystroke ring. EOF rather than an error is the contract sink.h states, so INPUT already handles it. That editor is the next piece of work there. 70/70 core ctest with no SDL on the include path, 71/71 with the akgl suite, clean under -Wall -Wextra, doxygen clean. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 08:46:53 -04:00
Andrew Kesterson	83185bafa8	Read the keyboard: implement GET, GETKEY and SCNCLR ... The poll_key half of group E, against the akbasic_InputBackend record. The libakgl implementation behind it is akgl_controller_poll_key(), which drains a ring the library fills from SDL events the host pumps -- so the interpreter can answer "is there a key waiting" without owning an event loop, which is what goal 3 requires. GET and GETKEY differ in one way and it is the interesting one. GET takes whatever is there including nothing, and an empty buffer is success with the empty string rather than an error -- that is what happens on most iterations of every GET loop ever written, and upstream is explicit that its poll reports it the same way. GETKEY waits, and since the library may not block, waiting is spelled as holding the step loop: the verb sets a flag and akbasic_runtime_step() declines to advance until a key arrives. Every step still returns and a bounded run() still comes back, so a host keeps its frame rate; the program simply does not move past the GETKEY. The PLAY queue is serviced before that check on purpose -- music should keep playing while a program waits for a keypress. Withdrawing the input device while a GETKEY is holding releases it rather than wedging the script on a device that no longer exists. Both verbs accept an integer variable as well as a string one and give it the raw key code, which is what a program testing for cursor or function keys needs. No key is code zero, matching what a C128 reports. A float variable is refused: it is neither a character nor a code. SCNCLR goes through the text sink rather than a device, because the sink is where PRINT already goes and is the only thing that knows what a screen means for this host. The stdio sink treats it as a no-op; clearing a pipe means nothing. One thing worth knowing before writing any bounded-run test, and now commented in tests/input_verbs.c: source lines are stored indexed by line number and the cursor starts at zero, so a step is spent on each empty slot along the way. A program at line 10 needs eleven steps before it has run anything. 70/70 ctest, clean under -Wall -Wextra, doxygen clean. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 08:35:05 -04:00