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Interpreter_SystemRegisters: Ensure FPSCR modifying instructions don't set bit 20

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Bit 20 is defined as being reserved and attempts to set it are ignored
by hardware, so we should be doing the same thing.
This commit is contained in:
Lioncash 2018-06-05 16:00:14 -04:00
parent 36ff2a20d5
commit 11a35d47ef
1 changed files with 29 additions and 10 deletions
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39
Source/Core/Core/PowerPC/Interpreter/Interpreter_SystemRegisters.cpp
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@ -58,15 +58,24 @@ void Interpreter::mtfsb0x(UGeckoInstruction inst)
Helper_UpdateCR1();
}
// This instruction can affect FX
void Interpreter::mtfsb1x(UGeckoInstruction inst)
{
// this instruction can affect FX
u32 b = 0x80000000 >> inst.CRBD;
if (b & FPSCR_ANY_X)
SetFPException(b);
else
FPSCR.Hex |= b;
FPSCRtoFPUSettings(FPSCR);
const u32 bit = inst.CRBD;
// Bit 20 in the FPSCR is reserved and defined as zero,
// so we ensure that we don't set it.
if (bit != 20)
{
const u32 b = 0x80000000 >> bit;
if (b & FPSCR_ANY_X)
SetFPException(b);
else
FPSCR.Hex |= b;
FPSCRtoFPUSettings(FPSCR);
}
if (inst.Rc)
Helper_UpdateCR1();
@ -74,10 +83,14 @@ void Interpreter::mtfsb1x(UGeckoInstruction inst)
void Interpreter::mtfsfix(UGeckoInstruction inst)
{
u32 mask = (0xF0000000 >> (4 * inst.CRFD));
u32 imm = (inst.hex << 16) & 0xF0000000;
// Bit 20 of the FPSCR is reserved and defined as zero on hardware,
// so ensure that we don't set it.
const u32 field = inst.CRFD;
const u32 pre_shifted_mask = field == 4 ? 0x70000000 : 0xF0000000;
const u32 mask = (pre_shifted_mask >> (4 * field));
const u32 imm = (inst.hex << 16) & pre_shifted_mask;
FPSCR.Hex = (FPSCR.Hex & ~mask) | (imm >> (4 * inst.CRFD));
FPSCR.Hex = (FPSCR.Hex & ~mask) | (imm >> (4 * field));
FPSCRtoFPUSettings(FPSCR);
@ -95,6 +108,12 @@ void Interpreter::mtfsfx(UGeckoInstruction inst)
m |= (0xFU << (i * 4));
}
// Bit 20 of the FPSCR is defined as always being zero
// (bit 11 in a little endian context), so ensure that
// we don't actually set that bit.
if ((fm & 0b100) != 0)
m &= 0xFFFFF7FF;
FPSCR.Hex = (FPSCR.Hex & ~m) | (static_cast<u32>(riPS0(inst.FB)) & m);
FPSCRtoFPUSettings(FPSCR);