5 Commits

Author SHA1 Message Date
13f1df03ef Unbreak the three example programs the RND merge left behind
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Adding native RND and ASC (ae2c702) made RND a function name, and a suffixed
identifier that collides with one is refused -- "SYNTAX ERROR Reserved word in
variable name". Three example programs held their PRNG output in a variable
called RND#, or a host field called RND%, and none of them had run since:

  - examples/galaga/ bound RND% as a host field on both ENEMY and GAME. The
    BASIC-visible name is ROLL% now; the C member stays `rnd`. This one was
    caught by example_galaga and example_galaga_interop, which have been
    failing.
  - examples/breakout/characters/breakout.bas and examples/megademo/
    megademo.bas both use RND# for their LCG output, renamed to ROLL#. Neither
    is in any test, so neither failure was visible.

examples/breakout/sprites/breakout.bas was broken a second way: seven REM lines
the reader refuses. Worth recording that the ceiling is not the one the message
names -- src/sink_stdio.c fails when the read filled the buffer without seeing
a terminator, so with AKBASIC_MAX_LINE_LENGTH at 80 the message says "79
character limit" and the real maximum is 78, because a 79-character line leaves
no room for the newline. The sweeps that fixed the corpus and the megademo for
this did not reach this file. The seven comments are reflowed.

The prose went stale with the code. Chapter 21 said "there is no RND verb in
this dialect; issue #16 tracks adding one", chapter 17's historical aside
offered an LCG that no longer parses, and four REM blocks across the two games
said the same thing. All of them now say RND exists, and say why these programs
keep their own generator anyway: the sequence has to be reproducible for a
headless run to be the same game on every machine, which is what lets
interop_test.c assert exact counts.

Chapter 21 also gains the rule that bit them, since a reader writing a host
type will hit it: a host field name is a bare word and shares a namespace with
every verb and function.

None of this came from the submodule bump -- all three were already broken on
main. It was found by running the tutorial games, which nothing else does;
that gap is akbasic issue #58.

Verified: all three run clean under the dummy drivers, and 114/114 default,
116/116 with akgl.

Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>
Co-Authored-By: Claude Code (Claude Opus 5, claude-opus-5[1m]) <noreply@anthropic.com>
2026-08-05 23:26:33 -04:00
ff1730e424 Teach the artwork tutorial the converted listing
Chapter 18 still taught the machinery the listing lost when it moved onto
SOLID and the persistent drawing layer: the frame-boundary PACE routine, the
flattened live list, the SSHAPE pool accounting, and the sixty lines of
BALLBRICKS/TESTCELL that computed a minimum translation axis by hand.

Step 8 now registers each brick with SOLID, arms COLLISION 2 and reads the
contact back with RCOLLISION, including the point that costs an evening if it
is missed: the BUMP mask is by sprite, and the balls are sprites 5, 6 and 7,
so their bits are 16, 32 and 64. The FOR-with-equal-bounds rule that every
one-item case in the chapter depends on is now stated where it is first used
rather than referred to from a step that no longer exists.

The listing loses six declarations orphaned by the conversion and the comment
blocks that still described the captures.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EwxGB6TdoVvZ11KQQME9cL
Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>
2026-08-02 13:13:51 -04:00
61f60a8859 Stop the artwork breakout drawing its screen into two sprites
It captured the HUD strip into sprite 1 and the whole play field into sprite 2,
and its own header called them "the screen". That was never a choice: a drawing
lasted one frame, so a sprite was the only thing the interpreter would redraw for
nothing. Both slots are free now, and five things went with them.

**`WINDOW 0, 35, 49, 36` is the first executable line.** The text layer repaints
every row it owns and by default owns the whole window; moved to two rows at the
bottom, it leaves the other thirty-five to the drawing verbs, and what the
program draws stays.

**`PACE` is gone.** It spun on `TI#` until a batch boundary so an `SSHAPE`
capture would not be cut in half by a present. Nothing is captured, so a drawing
spanning two batches simply arrives over two frames and the layer keeps both
halves. The 256-line drawing deadline that shaped every draw routine in this
listing does not apply to it any more.

**The flattened live list is gone** -- `BUILDLIVE`, `BUILDROW`, `STAMPROW` and
the four arrays behind them. They existed so a full-field redraw could be one
stamp and an advance per brick, and a full-field redraw existed because removing
one brick meant rebuilding all sixty. A broken brick is now erased in place with
a blank stamp, so the field is drawn once per level and not again.

**`BALLBRICKS` and `TESTCELL` are gone** -- about sixty lines that turned the
ball's box into a range of candidate cells, walked them with a nested `DO`, and
computed an overlap rectangle to pick an axis. `SOLID` registers each brick as
the level is laid out, `COLLISION 2` fires, and `RCOLLISION` says which brick,
which way out, how far, and which axis to reverse.

**The `SSHAPE` pool accounting is gone.** `SHN#` counted slots because every
frame's capture spent another and `GRAPHIC 5` had to throw them all away
periodically; eight are now spent once and never again.

Three mistakes worth recording, because each was silent:

- **The bricks were registered and then immediately thrown away.**
  `GOSUB BUILDLIVE` sat *after* the fill loop in `SETUPLEVEL` and meant "rebuild
  the list of what is standing"; replaced in place by a bare `SOLID`, it meant
  "retire everything" and ran after all sixty had been registered. Nothing
  failed -- the ball simply passed through the wall.
- **The handler tested the wrong bits.** `BUMP` is a mask by *sprite*, and the
  balls are sprites 5, 6 and 7, so their bits are 16, 32 and 64. Testing 1, 2 and
  4 asked about the HUD and field sprites that no longer exist.
- **The eraser stamps were undeclared**, so `SSHAPE` filled them inside
  `DRAWPROTOS` and they were empty everywhere else -- exactly the scope trap
  chapter 17 Step 3 is about, found by printing the handle inside the routine and
  again outside it.

Verified by driving it: a copy with a tracking paddle and auto-relaunch breaks
thirteen bricks in sixty seconds with no error line, and the shipped listing runs
clean. Both suites green.

Chapter 18 still describes the architecture this commit removed; that is the rest
of section 6 item 39.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EwxGB6TdoVvZ11KQQME9cL
Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>
2026-08-02 12:58:08 -04:00
8763da12c1 Stop the listings and their chapters stating fixed defects as fact
You were right that this was still everywhere. The two `.bas` files carried
their workarounds as present-tense statements about the interpreter -- "a name
first created inside a GOSUB costs a value slot that is never handed back",
"writing PAST the terminator of a short row draws nothing at all", "SSHAPE and
GSHAPE ignore the subscript on a string array", "a FOR inside a BEGIN block does
not survive the RETURN" -- and every one of those is now false. A comment that
lies is worse than no comment, and these were the first thing anybody opening
the files would read.

**The characters game takes the geometry fix.** `CW# = 16` becomes `CW# =
RGR(3)`, and the grid comes from `RWINDOW`, so the game fits whatever window and
font the host gives it. That was the one thing in the listing that would break on
a different font, and `RGR(3)` and `RWINDOW` were added to the interpreter
because of it -- leaving the constant in place while Chapter 17 teaches the
function was the inconsistency worth closing. `RGR(1)` still comes first so a
build with no graphics device refuses by naming the device that is missing.

Everything else in both listings keeps its shape and says why. Declaring every
name up front, guarding loops with `GOTO`, six scalars for six brick stamps: none
is forced any more and none costs anything, so they stay, with the comments
marking which rules stand and which are history. The sprites header's five traps
are marked FIXED where they are fixed.

The chapters follow: Chapter 17 Step 2 no longer says "the listing still has
`CW# = 16`", and Chapter 18's trap section is "five things that did not do what
they looked like" with the two that still stand named up front rather than left
to be counted.

Verified: Chapter 17 Step 2's block is once again verbatim from the listing, so
every quoted fragment in both chapters matches its source with no exceptions;
both games run 40 seconds on the SDL frontend with no error line; both suites
green in both configurations; `docs_examples` and `docs_screenshots --check`
pass.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>
2026-08-02 06:32:48 -04:00
0206bc75be 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>
Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>
2026-08-01 22:54:42 -04:00