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x86jit: Implement ReverseBits.

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Unknown W. Brackets 2023-09-17 13:16:45 -07:00
parent 24da5a3ba2
commit 580c9a634b
1 changed files with 31 additions and 0 deletions
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31
Core/MIPS/x86/X64IRCompALU.cpp
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@ -151,6 +151,37 @@ void X64JitBackend::CompIR_Bits(IRInst inst) {
break;
case IROp::ReverseBits:
regs_.Map(inst);
if (inst.src1 != inst.dest) {
MOV(32, regs_.R(inst.dest), regs_.R(inst.src1));
}
// Swap even/odd bits (in bits: 0123 -> 1032.)
LEA(32, SCRATCH1, MScaled(regs_.RX(inst.dest), 2, 0));
SHR(32, regs_.R(inst.dest), Imm8(1));
XOR(32, regs_.R(inst.dest), R(SCRATCH1));
AND(32, regs_.R(inst.dest), Imm32(0x55555555));
XOR(32, regs_.R(inst.dest), R(SCRATCH1));
// Swap pairs of bits (in bits: 10325476 -> 32107654.)
LEA(32, SCRATCH1, MScaled(regs_.RX(inst.dest), 4, 0));
SHR(32, regs_.R(inst.dest), Imm8(2));
XOR(32, regs_.R(inst.dest), R(SCRATCH1));
AND(32, regs_.R(inst.dest), Imm32(0x33333333));
XOR(32, regs_.R(inst.dest), R(SCRATCH1));
// Swap nibbles (in nibbles: ABCD -> BADC.)
MOV(32, R(SCRATCH1), regs_.R(inst.dest));
SHL(32, R(SCRATCH1), Imm8(4));
SHR(32, regs_.R(inst.dest), Imm8(4));
XOR(32, regs_.R(inst.dest), R(SCRATCH1));
AND(32, regs_.R(inst.dest), Imm32(0x0F0F0F0F));
XOR(32, regs_.R(inst.dest), R(SCRATCH1));
// Finally, swap the bytes to drop everything into place (nibbles: BADCFEHG -> HGFEDCBA.)
BSWAP(32, regs_.RX(inst.dest));
break;
case IROp::BSwap16:
CompIR_Generic(inst);
break;