13 Commits

Author	SHA1	Message	Date
Andrew Kesterson	8a50d07eef	Add the new refusal to the error-code appendix ... 512 gains its new cause: a branch by number to a line the program did not number. PARSE ERROR is what the prescans report as, since they run before any statement does, so the class table says so. 514 claimed a branch to a line that does not exist raises it. Nothing does -- AKBASIC_ERR_UNDEFINED comes from label, variable, field and host-struct lookups only, and GOTO 500 with no line 500 walks to the end and stops. That was already wrong before this work; it is more visible now that a branch to a line that does exist can be refused. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 16:52:47 -04:00
Andrew Kesterson	28ea99a638	Document optional line numbers ... Chapter 2 gets the rule and the refusal, chapter 4 gets the payoff for LABEL, chapter 9 says DSAVE writes the numbers it handed out and to RENUMBER first if you want gaps, chapter 10 shows a host loading numberless source, chapter 13 gets the QuickBASIC-shaped divergence, and chapter 14's source[] passage gets its second half. Chapter 14 said "two prescans" and listed two; there were three before this and there are four now, so it lists all four and says which of them reports against the right line. TODO.md section 6 records four things found on the way and deliberately not fixed: set_label() filing into the active scope rather than the root, three prescans reporting the wrong line number, duplicate written line numbers still replacing silently, and renumber.c's file-scope scratch arrays. examples/embed.c runs the same program twice, numbered and not, so the example compiles the feature rather than describing it. Its header pointed at ./build/examples/embed, which is not where the binary lands. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 16:43:14 -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	6bac929901	Document structures: a chapter, the architecture, and the differences ... docs/16-structures.md is the feature: records, nesting, copy-on-assign, strict pointers, lists, what is checked and what is not, and how a host shares its own C structs. Every example in it is executed by docs_examples and byte-compared, including the refusals -- so a message that changes fails the suite rather than quietly making the chapter wrong. The chapter makes one contrast explicitly, because it is the question a reader will actually have: a misspelled *field* is refused and a misspelled *variable* still prints zero. The rule underneath is that what the program declared gets checked and what it did not gets shrugged at -- a variable's name is never declared, a TYPE's field list is. Structures end up the strictest thing in the language, not from a higher standard but because they are the only named thing whose valid spellings are written down. Chapter 14 gains the layout: an instance is a contiguous run of value slots with a diagram of where the fields sit, the three-pass prescan and why each pass exists, why the copy cannot live in akbasic_value_clone(), and why the render depth bound is four rather than eight. Chapter 3 gains the @ suffix, chapter 13 records that all of this is an addition BASIC 7.0 has nothing like, and the verb reference gains TYPE, POINT and DIM ... AS. MAINTENANCE.md gains the two rules that are on a maintainer rather than on a test: a structure copy must not go through clone, and a field chain gets its own leaf field. TODO.md section 5 records what was invented and the three limits that are ours, and section 8 records the two defects the work exposed. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 12:03:02 -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	737fdc760f	Document every error code a script can see, as chapter 15 ... ER# held numbers nothing explained. The appendix lists the four error classes the interpreter prints, the eight codes it owns and what raises each, and the codes that reach ER# from errno, libakerror and libakgl underneath it. The table is not asserted. A program in the chapter trips seven of the eight and prints what it got, and docs_examples byte-compares the result -- so the numbers are checked rather than claimed. The eighth, 516, is not usefully trappable and the chapter says why: entering a handler takes a scope, and the pool being empty is what raised it. Two things worth a reader's attention came out of writing it. Two codes register the same ERR() text, so a program must compare the number and print the text. And VAL reports libakerror's Value Error rather than the interpreter's 517, which makes that number the platform's rather than ours -- filed as section 6 item 21, not fixed here, because deciding which libakstdlib failures to translate is a boundary question and ENOENT out of DOPEN is the counter-case. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-08-01 07:36:36 -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	80b76ad467	Split the documentation by who reads it ... README.md was 577 lines and answered four different questions at once: what the project is, how to build it, every verb and function in the language, and how to maintain the test harness. The verb and function lists had already been written a second time in docs/11 and docs/12, which is how a list of that size goes stale -- there is no way to notice the two have drifted apart. README.md is now 150 lines and holds only what somebody evaluating the project needs: what it is, the quickstart, why it was rewritten in C, the five rules embedding imposes on the design, the two ways to use it, and where everything else lives. Technical detail goes to docs/, maintenance to MAINTENANCE.md. The akbasic_TextSink struct moved to docs/10-embedding.md rather than being deleted. It was the corpus's only `c excerpt=` block -- the check that caught the stale struct two commits ago -- so dropping it with the README would have quietly retired a test. docs/10 also stopped claiming README.md carries the full API surface and the pool limits, which the trim made false. CLAUDE.md went from 458 lines to 62, because almost none of it was agent-specific. The project goals, the Go reference and its architecture, the dependency version and ABI rules, the four ways an embedded build collides, the libakerror convention, the error-code range map and the style rules are all things a maintainer needs, and they are now in MAINTENANCE.md with one copy to keep true. CLAUDE.md points there and keeps only the rules no test enforces: tests in the same commit asserting the correct contract, file a missing dependency capability upstream, do not edit generated output or tests/reference/, co-author your commits. Four claims did not survive the move, having gone stale where nothing could notice: - "The repository is currently empty apart from its submodules -- no commits, no source tree, no build files." There are 43 commits. - libakgl's target_compile_definitions(akerror PUBLIC AKERR_MAX_ERR_VALUE) at deps/libakgl/CMakeLists.txt:44, described as inert but present. It is gone; only a historical mention in a comment remains. - "akbasic_init() claims 512-767." There is no akbasic_init. It is akbasic_error_register(), called from akbasic_runtime_init(). - Time-relative phrasing ("libakgl hit two of them in the last week"). Five places pointed at CLAUDE.md for the range map or the file-it-upstream rule and now point at MAINTENANCE.md: include/akbasic/error.h, src/runtime_disk.c and three entries in TODO.md. Both source changes are comments. deps/libakgl/TODO.md cites it too and is left alone; it is a submodule, and the rule it quotes is still reachable from CLAUDE.md. ctest is green at 95 of 95, docs_examples included: 36 programs, 9 transcripts, 44 output comparisons, 3 C snippets, 1 excerpt. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 22:59:43 -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	cdaefcc941	Write the usage guide as thirteen chapters in docs/ ... Organised the way the C128 Programmer's Reference Guide is: the language first, then each hardware area, then the reference sections. One markdown file per chapter. The verb and function references are generated from the interpreter's own dispatch table, with an assertion that every row is described, so they cannot drift out of step with what the program accepts. 98 verbs and 30 functions. Every example was run before it was written down, which caught three claims that were wrong: a whole FOR loop on one line prints nothing rather than looping once, MID and INSTR count from zero where a C128 counts from one, and a multi-line DEF returns a value the caller has to assign away. Chapter 13 is the list a BASIC 7.0 programmer needs -- roughly sixty documented differences, including the two known FOR defects and the fact that drawing does not survive a frame. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>	2026-07-31 21:50:50 -04:00