Editing PS2 Emulation
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| In corner cases emu select wrong block flags pipeline state (both VU0/EEonBE and VU1/VRC affected). || This can cause various issues, mostly SPS, missing graphic, specific slowdowns, etc. Issue seems to occur when branch/jump delay slot have opcode important for flags calculation. Theory is that cached microprogram don't include modified flags state from delay slot instruction. So when already recompiled program is fetched from pool, it will miss one cycle in fmac flags pipeline. This can be crucial in games that rely on it. || Tales of Legendia and Klonoa 2 set sticky flag bits to 0 and branch with sub.xyzw in delay slot (expecting that sub change status flag), Tamsoft engine games set sticky bits to 0 in branch delay slot, this was most ridiculous bug, because problematic branch was pointing to next opcode after delay slot, removing branch was enough. True Crime: NY is only known game where VU0 is affected by this bug. more.. | | In corner cases emu select wrong block flags pipeline state (both VU0/EEonBE and VU1/VRC affected). || This can cause various issues, mostly SPS, missing graphic, specific slowdowns, etc. Issue seems to occur when branch/jump delay slot have opcode important for flags calculation. Theory is that cached microprogram don't include modified flags state from delay slot instruction. So when already recompiled program is fetched from pool, it will miss one cycle in fmac flags pipeline. This can be crucial in games that rely on it. || Tales of Legendia and Klonoa 2 set sticky flag bits to 0 and branch with sub.xyzw in delay slot (expecting that sub change status flag), Tamsoft engine games set sticky bits to 0 in branch delay slot, this was most ridiculous bug, because problematic branch was pointing to next opcode after delay slot, removing branch was enough. True Crime: NY is only known game where VU0 is affected by this bug. more.. | ||
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| CTC2 opcode write whole value to R register, while only 23 bits are writable. Rest is hardcoded to 0x3F800000. || Can cause many weird issues like broken physics, broken graphics. PCSX2 was also affected [[https://github.com/PCSX2/pcsx2/pull/6611 more]]. || | | CTC2 opcode write whole value to R register, while only 23 bits are writable. Rest is hardcoded to 0x3F800000. || Can cause many weird issues like broken physics, broken graphics. PCSX2 was also affected [[https://github.com/PCSX2/pcsx2/pull/6611 more]]. || There is only one game that is known to be affected, and is already partially patched (patch still break fog), is Musashi Samurai Legend. | ||
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| CFC2 from R register should return only 23 lower bits. || CFC2 from R on real PS2 return only lower 23 bits. Originally found out by PCSX2 team [[https://github.com/PCSX2/pcsx2/pull/8409 more]] and later confirmed to affect ps2_netemu in emu assembly. || There is only one game that is known to be affected, Onimusha Dawn of Dreams. | | CFC2 from R register should return only 23 lower bits. || CFC2 from R on real PS2 return only lower 23 bits. Originally found out by PCSX2 team [[https://github.com/PCSX2/pcsx2/pull/8409 more]] and later confirmed to affect ps2_netemu in emu assembly. || There is only one game that is known to be affected, Onimusha Dawn of Dreams. | ||