dolphin/docs/DSP/free_dsp_rom/dsp_rom_readme.txt
Michael Maltese e3531d17d7 Update free DSP ROM and coefficients to support GBA ucode
- coef: Explicitly set 23 different values that are used by GBA UCode,
  and tweaked overall parameters to more closely match those 23 values.
- irom: Moved a few functions to their proper places, updated BootUCode
  to configure DMA transfers using AX registers as well as IX registers
  (the GBA UCode uses this to do two sequential transfers in one call),
  and added partial functions used by GBA UCode.

All functions were reverse-engineered solely based off of observed
effects on the virtual machine: register states before-and-after, dmem
interactions, and DMA transfers. The specific coefficients were observed
being read from dmem, and must be exactly those values to function
properly. I have no knowledge of how the official ROM implements these
functions, or how it is implemented overall.

Tested with The Legend of Zelda: Four Swords Adventures, Final Fantasy
Crystal Chronicles, and Billy Hatcher and the Giant Egg (to download
ChuChu Rocket!).
2017-06-03 15:16:39 -07:00

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Legal GC/WII DSP IROM replacement (v0.3)
-------------------------------------------------------
- coef: Explicitly set 23 different values that are used by GBA UCode, and
tweaked overall parameters to more closely match those 23 values.
- irom: Moved a few functions to their proper places, updated BootUCode to
configure DMA transfers using AX registers as well as IX registers (the GBA
UCode uses this to do two sequential transfers in one call), and added
partial functions used by GBA UCode.
ligfx
2/june/2017
Legal GC/WII DSP IROM replacement (v0.2.1)
-------------------------------------------------------
- coef: 4-tap polyphase FIR filters
- irom: unchanged
Coefficients are roughly equivalent to those in the official DROM.
Improves resampling quality greatly over linear interpolation.
See generate_coefs.py for details.
stgn
29/june/2015
Legal GC/WII DSP IROM replacement (v0.2)
-------------------------------------------------------
- coef: crafted to use a linear interpolation when resampling (instead of
having a real 4 TAP FIR filter)
- irom: added all the mixing functions, some functions not used by AX/Zelda are
still missing
Should work with all AX, AXWii and Zelda UCode games. Card/IPL/GBA are most
likely still broken with it and require a real DSP ROM.
delroth
16/march/2013
Legal GC/WII DSP IROM replacement (v0.1)
-------------------------------------------------------
- coef: fake (zeroes)
- irom: reversed and rewrote ucode loading/reset part, everything else is missing
Good enough for Zelda ucode games (and maybe some AX too):
- WII: SMG 1/2, Pikmin 1/2 WII, Zelda TP WII, Donkey Kong Jungle Beat (WII), ...
- GC: Mario Kart Double Dash, Luigi Mansion, Super Mario Sunshine, Pikmin 1/2, Zelda WW, Zelda TP, ...
Basically... If game is not using coef and irom mixing functions it will work ok.
Dolphin emulator will report wrong CRCs, but it will work ok with mentioned games.
LM
31/july/2011