Entry 243

The executable's microcode names and .mwcats, the sound banks' unused parts

2026-09-27format

Filesdocs/engine/executable.mddocs/formats/snddata.md

Asked for: more of the docs' open questions. docs/engine/executable.md is now solid; docs/formats/snddata.md is down to one question about the hardware.

The executable

• The mc_* names. The 26 undefined mc* symbols are the VU entry points; the draw path already had their table. Checked here against the bytes:

  • the code references 21 of them;
  • each one's relocated lui/addiu value is its _$ label's byte address in micro memory: the offset from the MPG code before it, plus that MPG's load address times 8.

  The other five have labels but no EE caller. The ten type-123 relocations hold their target label's micro address (>> 3) in the 15-bit immediate, all ten.

• .mwcats. One section per code section (sh_link), not loaded: a record per function built by the Metrowerks compiler.

  • Kind 2 holds a 16-bit size and the address. Kind 3 has a 32-bit size, used for the only two functions of 32 KiB or more (ccEvent::Execute, ccEffect::Main).
  • Flag bit 0 adds the offset of the function's closing j. It is set on exactly the 25 functions that end in a tail jump, always at size minus 8.

  Every record matches a function symbol.

  • Records: all of gcmn.prg's and toppage.prg's functions, all but ccKanji::ccKanji in demo.prg and desktop.prg, and 1,351 of main's 2,241.
  • main's missing ones: the SCE libraries, newlib and libgcc (other compilers), and twelve out-of-line header inlines (binding 13).

The sound banks

• The SE tables. spcSeTbl, enemySeTbl and strSndTbl were already covered in the sound engine page; the entry was stale.

• seTimbre, Song, SE sequences. All absent: -1 in all 79 Heads, and in all 150 Sequs' Song, SE sequence and SE song. The code asks for none of them either:

  • sceHSyn_Load reads seTimbre (the banks are Vers 2) and skips a -1;
  • SNDBASE.IRX, the only importer of MODMIDI.IRX, never selects a Song;
  • no loaded module plays SE sequences.

• ADPCM rounding. Still open.

  • The port rounds the sum as PCSX2 does: (s1*F0 + s2*F1 + 32) >> 6.
  • DuckStation shifts each product on its own, without rounding.

  What the SPU2 does needs a measurement on the console.