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decode: remove unnecessary shifts

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This commit is contained in:
Alexis Engelke
2022-11-01 20:43:37 +01:00
parent a05d52fdd0
commit 0c20aa4f19
1 changed files with 6 additions and 6 deletions
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12
decode.c
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@@ -358,9 +358,9 @@ prefix_end:
{ {
FdOp* op_modrm = &instr->operands[DESC_MODRM_IDX(desc)]; FdOp* op_modrm = &instr->operands[DESC_MODRM_IDX(desc)];
unsigned mod = (op_byte & 0xc0) >> 6; unsigned mod = op_byte & 0xc0;
unsigned rm = op_byte & 0x07; unsigned rm = op_byte & 0x07;
if (mod == 3) if (mod == 0xc0)
{ {
uint8_t reg_idx = rm; uint8_t reg_idx = rm;
unsigned reg_ty = DESC_REGTY_MODRM(desc); // GPL VEC - - MMX FPU MSK unsigned reg_ty = DESC_REGTY_MODRM(desc); // GPL VEC - - MMX FPU MSK
@@ -381,13 +381,13 @@ prefix_end:
if (UNLIKELY(off >= len)) if (UNLIKELY(off >= len))
return FD_ERR_PARTIAL; return FD_ERR_PARTIAL;
uint8_t sib = buffer[off++]; uint8_t sib = buffer[off++];
unsigned scale = (sib & 0xc0) >> 6; unsigned scale = sib & 0xc0;
unsigned idx = (sib & 0x38) >> 3; unsigned idx = (sib & 0x38) >> 3;
idx += prefix_rex & PREFIX_REXX ? 8 : 0; idx += prefix_rex & PREFIX_REXX ? 8 : 0;
base = sib & 0x07; base = sib & 0x07;
if (!vsib && idx == 4) if (!vsib && idx == 4)
idx = FD_REG_NONE; idx = FD_REG_NONE;
op_modrm->misc = (scale << 6) | idx; op_modrm->misc = scale | idx;
} }
else else
{ {
@@ -407,14 +407,14 @@ prefix_end:
else else
op_modrm->reg = base + (prefix_rex & PREFIX_REXB ? 8 : 0); op_modrm->reg = base + (prefix_rex & PREFIX_REXB ? 8 : 0);
if (mod == 1) if (mod == 0x40)
{ {
if (UNLIKELY(off + 1 > len)) if (UNLIKELY(off + 1 > len))
return FD_ERR_PARTIAL; return FD_ERR_PARTIAL;
instr->disp = (int8_t) LOAD_LE_1(&buffer[off]); instr->disp = (int8_t) LOAD_LE_1(&buffer[off]);
off += 1; off += 1;
} }
else if (mod == 2 || (mod == 0 && base == 5)) else if (mod == 0x80 || (mod == 0 && base == 5))
{ {
if (UNLIKELY(off + 4 > len)) if (UNLIKELY(off + 4 > len))
return FD_ERR_PARTIAL; return FD_ERR_PARTIAL;