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R5900: Fix LWL not sign extending in interpreter

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This was zero extending because of the implicit promotion from
signed->unsigned, causing incorrect high bits in the GPR.

Funnily enough, this was noted in the source, but implemented
incorrectly.
This commit is contained in:
Connor McLaughlin
2021-09-09 17:36:36 +10:00
committed by refractionpcsx2
parent 9722bcd3c3
commit a8a50641f6
1 changed files with 4 additions and 4 deletions
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8
pcsx2/R5900OpcodeImpl.cpp
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@@ -595,13 +595,13 @@ void LWL()
s32 addr = cpuRegs.GPR.r[_Rs_].UL[0] + _Imm_;
u32 shift = addr & 3;
// ensure the compiler does correct sign extension into 64 bits by using s32
s32 mem = memRead32(addr & ~3);
u32 mem = memRead32(addr & ~3);
if (!_Rt_) return;
cpuRegs.GPR.r[_Rt_].SD[0] = (cpuRegs.GPR.r[_Rt_].SL[0] & LWL_MASK[shift]) |
(mem << LWL_SHIFT[shift]);
// ensure the compiler does correct sign extension into 64 bits by using s32
cpuRegs.GPR.r[_Rt_].SD[0] = (s32)((cpuRegs.GPR.r[_Rt_].UL[0] & LWL_MASK[shift]) |
(mem << LWL_SHIFT[shift]));
/*
Mem = 1234. Reg = abcd