SOUND, ENVELOPE, VOL, PLAY and TEMPO against the akbasic_AudioBackend record,
plus FILTER, which is in the table only so that it can be refused with a reason.
The PLAY note-string parser and TEMPO are here rather than in libakgl because
that is where its audio commit says they belong: a tone generator synthesises
pitches, but deciding that O4CDEFG is five quarter notes starting at middle C is
a language question.
PLAY does not block. On a C128 it holds the program until the last note ends,
which section 1.6 forbids outright, so it parses the string into a fixed queue
and returns; akbasic_runtime_step() releases one note at a time against whatever
time the host last passed to akbasic_runtime_settime(). The driver now steps one
at a time with the clock refreshed in between rather than making a single
unbounded run() call -- a tune whose notes all measured themselves against a
frozen zero would rush out at once. That loop is its own function because CATCH
expands to a break and PASS expands to a return of the context, and main()
returns an int; wrapping the loop is what the protocol prescribes for that shape.
src/audio_tables.c holds the three conversions, laid out as tables because each
is somewhere a wrong constant produces a plausible wrong pitch rather than an
error anybody would notice. Two are transcriptions -- the SID frequency formula
and its non-linear ADSR rate tables, where decay is exactly three times attack.
The third is not: BASIC 7.0 never published what a whole note lasts at a given
TEMPO, so 16000 ms at TEMPO 1 is a calibration choice putting a default quarter
note at 120 bpm, and it is labelled as a choice where it is made.
SOUND's frequency sweep is refused rather than faked, and filed upstream as
akgl_audio_sweep. The only way to fake it here is to re-issue tones from step(),
which ties audible pitch to how often the host calls us -- a tune that changes
key with the frame rate. FILTER is refused for the reason upstream already gave:
there is no filter stage and SDL3 has no primitive to build one from.
The PLAY parser is tested through akbasic_play_parse() directly rather than
through a program, because running one also runs the queue service -- and with
the clock at zero every duration has already expired, so the queue empties before
an assertion can look at it. Draining is correct behaviour and is tested on its
own; the parse tests ask a different question.
68/68 ctest, clean under -Wall -Wextra, doxygen clean.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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>
