9d99d0a67e8acb90199e803185b02d6cb74930de
4 Commits
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9d99d0a67e
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Draw: implement the BASIC 7.0 graphics verbs
GRAPHIC, COLOR, DRAW, BOX, CIRCLE, PAINT, SCALE, SSHAPE, GSHAPE and LOCATE, all against the akbasic_GraphicsBackend record rather than akgl_draw_* directly, so src/runtime_graphics.c includes no SDL and the whole group is testable in a build with no SDL on the machine. The reference lists every one of these as unimplemented, so the semantics come from Commodore BASIC 7.0 rather than from a port, and four places where a modern renderer cannot do what a C128 did are recorded in TODO.md section 5 rather than silently substituted: - CIRCLE is drawn as a polygon of inc-degree segments and akgl_draw_circle is deliberately unused. 7.0's CIRCLE takes two radii, an arc range and a rotation, so the primitive could serve only the fully-defaulted call, and a shape that changed character depending on whether the radii happened to be equal would be worse than one uniformly a polygon. - SSHAPE puts a SHAPE:<n> handle in the string variable rather than the pixels, because a value's string is a fixed 256 bytes and a region is a device surface. GSHAPE refuses a string without that prefix instead of parsing whatever digits it finds and pasting an unrelated slot. - BOX fills on a negative angle; 7.0 puts the fill flag after the rotation, which would make a filled box a seventh argument. - GRAPHIC stores its mode and honours only the one consequence that means anything here -- mode 0 is text -- while still refusing an out-of-range mode, since that is a typo worth catching. PAINT surfaces the flood fill's AKERR_OUTOFBOUNDS as an error rather than success. The device gives up when its span stack runs out having filled *part* of the region, and a program that cannot tell that happened cannot recover from it. Note the shape of that handler: HANDLE sets handled = true on the context, so a FAIL_RETURN from inside the HANDLE block hands the caller something already marked handled, whose FINISH_LOGIC then declines to pass it up and releases it -- the error disappears and PAINT reports success. Flag inside the block, raise after FINISH. COLOR, LOCATE and SCALE need no device on purpose, so a program can set itself up before a host has lent it a renderer. Adds a second golden corpus under tests/language/. The corpus in deps/basicinterpret is a submodule and nothing here may add files to it, but goal 2's new verbs still need the .bas/.txt half of their coverage. Registered under local_ so a failure names which corpus it came from. What it can cover is limited -- these verbs draw rather than print -- so the behaviour that reaches a device is asserted against tests/mockdevice.h instead. 65/65 ctest, clean under -Wall -Wextra, doxygen clean. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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9b9dd09c5a
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Reach hardware through backend records, and take the time from the host
Groups G, I and E are unblocked but cannot be written yet: the core library is free of SDL and builds with no libakgl present, so a graphics verb cannot call akgl_draw_* and a sound verb cannot call akgl_audio_*. This adds what they call instead. Three records of function pointers -- akbasic_GraphicsBackend, _AudioBackend and _InputBackend -- in the same shape as akbasic_TextSink, and the same shape libakgl uses for akgl_RenderBackend. akbasic_runtime_set_devices() attaches any subset; all three may be NULL and that is the standalone driver's normal state, so a runtime with no backends still comes up and still prints. A verb that needs one it was not given raises the new AKBASIC_ERR_DEVICE rather than dereferencing a NULL vtable. Two decisions worth stating. The graphics record has no circle entry point: BASIC 7.0's CIRCLE takes two radii, an arc range, a rotation and a degree increment, which makes it a polygon by definition, so it will be built from line calls rather than from akgl_draw_circle. And coordinates are double rather than an integer pixel address, because SCALE makes them fractional and rounding at each verb rather than once at the backend accumulates drift along a polyline. akbasic_runtime_settime() is how SOUND, PLAY and TEMPO get a clock without the library reading one. Section 1.6 forbids blocking or owning a loop, so the caller that owns the frame owns the time -- which is what libakgl already does, since akgl_actor_logic_changeframe takes curtimems as an argument. Left unset it is zero and every duration expires immediately: audible, but never a hang. AKBASIC_ERR_LAST is a sentinel rather than a status, so tests/error_codes.c walks every code looking for an unnamed one without anybody remembering to widen the loop when a code is added. tests/mockdevice.h records every backend call as a formatted line. The graphics and audio verbs emit nothing a golden file can compare, so that log is where their assertions have to live -- and since it needs no SDL, the whole of groups G, I and E stays testable in the default build. 62/62 ctest, clean under -Wall -Wextra, doxygen clean. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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cde6fa8f59
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Port the README from the Go version and document embedding
Carries the reference README across, adjusted where C changes the answer: cmake instead of make, the ak* libraries instead of the go-sdl2 bindings, and the limits table now includes the three ceilings the Go version did not need because it called make(). The new "Embedding the interpreter" section is the point of the rewrite, so it states the four rules the library holds to -- nothing terminates the process, nothing calls malloc, no file-scope mutable state, the host owns the loop -- and each was checked against the tree rather than asserted. Adds akbasic_runtime_load(). Writing the section turned up a real gap: a host usually already holds its script as a string and wants the sink reserved for output, and the only path that existed was AKBASIC_MODE_RUNSTREAM reading the program through the sink's readline, which forces a game to point its output device at its source text. The alternative was reaching into the header's "internal API" block for store_line. Neither is something to put in a README. Adds examples/embed.c, which is the code the README quotes -- a custom sink, a bounded per-frame run, and the PASS-not-CATCH rule for a loop inside an ATTEMPT. It is built by every build and registered as a CTest case, so a signature change breaks the build instead of rotting the document. The README's own snippet is compiled separately as a check; both were run before committing. The "What Isn't Implemented / Isn't Working" section leads with the eleven inherited defects rather than burying them, because five of them were found by this port and a reader deserves to know that 1 - 2 - 3 computes 1 - 2 before they hit it. Corrected two claims while verifying: the runtime is 10.1MB rather than the ~8MB first written, and its largest single cost is the environment pool at 4.1MB, not the source table. ctest 60/60; ASan+UBSan 60/60; no warnings under -Wall -Wextra. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> |
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f8c15c2f2c
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Port the BASIC interpreter from Go to C
Reproduces deps/basicinterpret in C, in the idiom of the ak* libraries. All 41
.bas files in the reference's corpus produce byte-identical stdout, including
the trailing double newline on an error line -- that comes from basicError
building a string ending in \n and handing it to Println, and
array_outofbounds.txt encodes it.
The corpus is driven in place from the submodule as 41 individual CTest cases
rather than copied, so it cannot drift from upstream. Eighteen unit tests cover
what the corpus cannot reach.
Three structural changes carry most of the work. Go's three reflection lookups
(Command*, Function*, ParseCommand*) become one sorted dispatch table in
src/verbs.c searched with bsearch; adding a verb is a row and two functions. The
five Go maps become one fixed open-addressed table over aksl_strhash_djb2. And
run(), which owned the process until MODE_QUIT, splits into step() plus a
bounded run() -- goal 3 requires a host game to be able to bound execution, and
nothing in the library now terminates the process or touches SDL.
Output goes through an akbasic_TextSink vtable. src/sink_stdio.c is what makes
the corpus runnable with no SDL present; the akgl-backed sink is still to come
and is blocked on libakgl having no text-measurement call.
src/convert.c exists because libakstdlib's aksl_ato* family cannot report a
conversion failure (its TODO.md 2.1.5). The reference checks strconv's error at
four sites and turns it into a BASIC error; routing those through aksl_atoi
would have turned four diagnosable errors into wrong answers, with VAL("garbage")
quietly returning 0. TODO.md 1.9 records which libakstdlib calls are cleared for
use here and which are not.
Reference defects are reproduced, not fixed: the golden files encode the observed
behaviour and a silent correction is a behaviour change. TODO.md section 6 lists
sixteen, and tests/known_reference_defects.c asserts the *correct* contract for
six of them under AKBASIC_KNOWN_FAILING_TESTS, so a fix shows up as
"unexpectedly passed". Five of the sixteen were found by this port and are new:
subtraction stops after one operator so 1-2-3 computes 1-2 and abandons the rest
of the line (a wrong answer, not a refused one); a unary-minus argument inflates
a function's arity so ABS(-9) is rejected; a comparison operator in a line's
final column is dropped; hex literals never survive the scanner; and the
"Reserved word in variable name" check is dead code.
Where the reference reaches undefined behaviour by a route that is defined in Go
-- an out-of-range shift, a negative string multiplier, integer division by zero
-- this raises instead of inheriting the UB. No golden case exercises any of
them.
The top-level CMakeLists shadows add_test, set_tests_properties and
add_custom_target around all three add_subdirectory calls. Without it libakerror's
tests land in our suite as Not Run, and its un-namespaced `coverage` target stops
a coverage build from configuring at all. Test targets are akbasic_test_<name>:
bare test_<name> collides with libakstdlib's, which is what broke libakgl's
configure in c2b16d3.
ctest 59/59; ASan+UBSan 59/59; 92.3% line and 96.9% function coverage; no
warnings under -Wall -Wextra. Branch coverage is not a target, for the reason
libakstdlib and libakgl both record: the akerror macros expand into large branch
trees at every call site.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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