Fix ADPCM sample buffer overread in audio synthesis (#6364)

The sampleDataStartPad and aligned variables existed solely to satisfy
the N64 RSP DMA requirement that source addresses be 16-byte aligned.
On PC, aLoadBuffer is a plain memcpy with no such constraint.

The alignment dance caused aLoadBuffer to read up to 15 bytes before
sampleData and up to 8+ bytes past the end of the sample buffer. On
platforms with strict allocator guard pages (e.g. OpenBSD), this
triggers a SIGSEGV.

A second issue remains after removing the alignment dance: nFramesToDecode
is derived from sample counts (loopEnd), but size is not always a multiple
of frameSize. loopEnd and size are derived independently during encoding
and can disagree on the final partial frame, leaving nFramesToDecode *
frameSize exceeding the remaining bytes in the buffer.

Remove sampleDataStartPad and aligned entirely. Clamp the load to
min(nFramesToDecode * frameSize, audioFontSample->size - sampleDataOffset).
The ADPCM decoder operates on DMEM, so a partial last frame in DMEM
produces at most a negligible artifact at sound termination.

0 files changed, 0 insertions, 0 deletions