akbasic

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Author	SHA1	Message	Date
Tachikoma	f9742ed5a5	Cut akbasic_Runtime's static footprint from 10.75 MiB to 2.40 MiB Nothing in this interpreter mallocs; every pool is a fixed array sized by an AKBASIC_MAX_* constant, so sizeof(akbasic_Runtime) is a compile-time number and most of it was headroom nobody was using. Measured concurrent-use high-water marks off examples/breakout and examples/megademo -- the two most demanding programs this interpreter runs -- against each pool's ceiling: AKBASIC_MAX_ENVIRONMENTS 32 -> 12 (measured peak concurrency: 6-7) AKBASIC_MAX_FUNCTIONS 64 -> 8 (measured: 0, neither program uses DEF FN) AKBASIC_MAX_ARRAY_VALUES 4096 -> 2048 (measured peak: 1618 slots) AKBASIC_MAX_SOURCE_LINES 9999 -> 2048 (measured: ~1270-1496 non-blank lines) AKBASIC_SYMTAB_MAX_SLOTS 256 -> 172 (no caller ever requests more than 128) AKBASIC_SYMTAB_MAX_KEY 64 -> 24 (longest identifier measured: 11 chars) AKBASIC_MAX_LINE_LENGTH 256 -> 80 (Commodore BASIC's own line limit) AKBASIC_MAX_VARIABLES (128) is untouched on purpose: breakout alone reaches 121 of 128 concurrent named variables, so it has the least slack of any pool measured and is not a shrink candidate. akbasic_Variable.name shrinks from AKBASIC_MAX_STRING_LENGTH (256) to AKBASIC_SYMTAB_MAX_KEY: every variable name is registered with akbasic_symtab_set() right after this field is populated (akbasic_environment_create(), src/environment.c), and that call already refuses anything AKBASIC_SYMTAB_MAX_KEY characters or longer. The wider field was headroom nothing could ever put a byte into. Two defects surfaced while testing the line-length drop against the golden corpus, both fixed here because the 80-byte ceiling makes them routine rather than theoretical: - sourcepath (runtime.h) was borrowing AKBASIC_MAX_LINE_LENGTH by accident. It holds a directory, not a line of BASIC, and this checkout's own test paths are 81+ characters deep -- every golden test failed to load until this split into its own AKBASIC_MAX_SOURCE_PATH_LENGTH, backed by PATH_MAX the way libakerror already sizes its own path buffers. - src/sink_stdio.c's stdio_readline() called aksl_fgets() but never checked its own documented contract: a full buffer with no trailing newline means the line was longer than the buffer, and the unread remainder is still in the stream. Unchecked, the next readline() picks that remainder up as its own statement -- a real line silently becomes two wrong ones instead of a clean AKBASIC_ERR_BOUNDS refusal. At 256 bytes this was theoretical; at 80 it is not, so it now refuses loudly. tests/value_pool.c's test_pool_is_untouched_by_scopes() was pinned to the old 4x1024=4096 pool math (four max-size arrays proving nothing leaked); rewritten to 2x1024=2048 for the same proof against the new AKBASIC_MAX_ARRAY_VALUES. Known consequence, tracked in andrew/akbasic#32 rather than worked around here: two files in the protected tests/reference/ corpus (language/functions/mod.bas, language/flowcontrol/nestedforloopwaitingfor command.bas) have 82-character lines and cannot be shortened -- MAINTENANCE.md and CMakeLists.txt:585 are explicit that tests/reference/ is never edited to suit this interpreter. Twelve tests/language/ cases and one docs/18 line are in the same position but are this project's own content. Shipping 80 anyway, with the fallout tracked rather than hidden, was an explicit call on this PR rather than something decided here. Verified: cmake --build build-akgl && ctest --test-dir build-akgl, 97/112 (15 known failures, all AKBASIC_MAX_LINE_LENGTH-related, filed as #32). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>	2026-08-04 20:05:41 -04:00
Tachikoma	4e188b2794	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> Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>	2026-07-30 23:53:56 -04:00

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Tachikoma

f9742ed5a5

Cut akbasic_Runtime's static footprint from 10.75 MiB to 2.40 MiB

Nothing in this interpreter mallocs; every pool is a fixed array sized by an
AKBASIC_MAX_* constant, so sizeof(akbasic_Runtime) is a compile-time number
and most of it was headroom nobody was using. Measured concurrent-use
high-water marks off examples/breakout and examples/megademo -- the two most
demanding programs this interpreter runs -- against each pool's ceiling:

  AKBASIC_MAX_ENVIRONMENTS   32 -> 12    (measured peak concurrency: 6-7)
  AKBASIC_MAX_FUNCTIONS      64 -> 8     (measured: 0, neither program uses DEF FN)
  AKBASIC_MAX_ARRAY_VALUES 4096 -> 2048  (measured peak: 1618 slots)
  AKBASIC_MAX_SOURCE_LINES 9999 -> 2048  (measured: ~1270-1496 non-blank lines)
  AKBASIC_SYMTAB_MAX_SLOTS  256 -> 172   (no caller ever requests more than 128)
  AKBASIC_SYMTAB_MAX_KEY     64 -> 24    (longest identifier measured: 11 chars)
  AKBASIC_MAX_LINE_LENGTH   256 -> 80    (Commodore BASIC's own line limit)

AKBASIC_MAX_VARIABLES (128) is untouched on purpose: breakout alone reaches
121 of 128 concurrent named variables, so it has the least slack of any pool
measured and is not a shrink candidate.

akbasic_Variable.name shrinks from AKBASIC_MAX_STRING_LENGTH (256) to
AKBASIC_SYMTAB_MAX_KEY: every variable name is registered with
akbasic_symtab_set() right after this field is populated
(akbasic_environment_create(), src/environment.c), and that call already
refuses anything AKBASIC_SYMTAB_MAX_KEY characters or longer. The wider field
was headroom nothing could ever put a byte into.

Two defects surfaced while testing the line-length drop against the golden
corpus, both fixed here because the 80-byte ceiling makes them routine rather
than theoretical:

- sourcepath (runtime.h) was borrowing AKBASIC_MAX_LINE_LENGTH by accident.
  It holds a directory, not a line of BASIC, and this checkout's own test
  paths are 81+ characters deep -- every golden test failed to load until
  this split into its own AKBASIC_MAX_SOURCE_PATH_LENGTH, backed by PATH_MAX
  the way libakerror already sizes its own path buffers.

- src/sink_stdio.c's stdio_readline() called aksl_fgets() but never checked
  its own documented contract: a full buffer with no trailing newline means
  the line was longer than the buffer, and the unread remainder is still in
  the stream. Unchecked, the next readline() picks that remainder up as its
  own statement -- a real line silently becomes two wrong ones instead of a
  clean AKBASIC_ERR_BOUNDS refusal. At 256 bytes this was theoretical; at 80
  it is not, so it now refuses loudly.

tests/value_pool.c's test_pool_is_untouched_by_scopes() was pinned to the old
4x1024=4096 pool math (four max-size arrays proving nothing leaked); rewritten
to 2x1024=2048 for the same proof against the new AKBASIC_MAX_ARRAY_VALUES.

Known consequence, tracked in andrew/akbasic#32 rather than worked around
here: two files in the protected tests/reference/ corpus
(language/functions/mod.bas, language/flowcontrol/nestedforloopwaitingfor
command.bas) have 82-character lines and cannot be shortened -- MAINTENANCE.md
and CMakeLists.txt:585 are explicit that tests/reference/ is never edited to
suit this interpreter. Twelve tests/language/ cases and one docs/18 line are
in the same position but are this project's own content. Shipping 80 anyway,
with the fallout tracked rather than hidden, was an explicit call on this PR
rather than something decided here.

Verified: cmake --build build-akgl && ctest --test-dir build-akgl, 97/112 (15
known failures, all AKBASIC_MAX_LINE_LENGTH-related, filed as #32).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>

2026-08-04 20:05:41 -04:00

Tachikoma

4e188b2794

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>
Co-Authored-By: Andrew Kesterson <andrew@aklabs.net>

2026-07-30 23:53:56 -04:00

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