arno/bddisasm
1
0
Fork 0
mirror of https://github.com/bitdefender/bddisasm.git synced 2024-12-22 05:58:07 +00:00
Code Issues Releases Wiki Activity

Optimized ror/rol/rcr/rcl instruction emulation - don't use slow loops anymore.

Browse Source
This commit is contained in:
BITDEFENDER\vlutas 2023-06-01 21:28:30 +03:00
parent d16f1d8ba3
commit f293c936ee
1 changed files with 48 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

81
bdshemu/bdshemu.c
View File

@ -2145,93 +2145,107 @@ ShemuEmulate(
case ND_INS_ROL:
case ND_INS_ROR:
{
ND_UINT32 cnt, tempcnt, cntmask;
ND_UINT32 cnt, tempcnt, cntmask, bitwidth;
ND_UINT8 tempCF = 0;
GET_OP(Context, 0, &dst);
GET_OP(Context, 1, &src);
cnt = (ND_UINT32)src.Value.Qwords[0];
tempcnt = 0;
cntmask = ((dst.Size == 8) ? 0x3F : 0x1F);
tempcnt = (cnt & cntmask);
bitwidth = (ND_UINT32)dst.Size * 8;
if (ND_INS_RCL == Context->Instruction.Instruction ||
ND_INS_RCR == Context->Instruction.Instruction)
{
switch (dst.Size)
if (dst.Size == 1)
{
case 1: tempcnt = (cnt & 0x1F) % 9; break;
case 2: tempcnt = (cnt & 0x1F) % 17; break;
case 4: tempcnt = (cnt & 0x1F); break;
case 8: tempcnt = (cnt & 0x3F); break;
default: break;
tempcnt %= 9;
}
else if (dst.Size == 2)
{
tempcnt %= 17;
}
}
else
{
tempcnt = (cnt & cntmask) % (dst.Size * 8);
tempcnt %= (dst.Size * 8);
}
if (ND_INS_RCL == Context->Instruction.Instruction)
{
while (tempcnt != 0)
tempCF = GET_FLAG(Context, NDR_RFLAG_CF);
if (tempcnt != 0)
{
tempCF = ND_MSB(dst.Size, dst.Value.Qwords[0]);
dst.Value.Qwords[0] = (dst.Value.Qwords[0] << 1) + GET_FLAG(Context, NDR_RFLAG_CF);
SET_FLAG(Context, NDR_RFLAG_CF, tempCF);
tempcnt--;
// tempcnt is in range [1, dst bit width].
ND_UINT64 left = (tempcnt == bitwidth) ? 0 : (dst.Value.Qwords[0] << tempcnt);
ND_UINT64 right = (tempcnt == 1) ? 0 : (dst.Value.Qwords[0] >> (bitwidth - tempcnt + 1));
SET_FLAG(Context, NDR_RFLAG_CF, ND_GET_BIT(bitwidth - tempcnt, dst.Value.Qwords[0]));
dst.Value.Qwords[0] = left | ((ND_UINT64)tempCF << (tempcnt - 1)) | right;
}
if ((cnt & cntmask) == 1)
{
SET_FLAG(Context, NDR_RFLAG_OF, ND_MSB(dst.Size, dst.Value.Qwords[0]) ^
GET_FLAG(Context, NDR_RFLAG_CF));
GET_FLAG(Context, NDR_RFLAG_CF));
}
}
else if (ND_INS_RCR == Context->Instruction.Instruction)
{
tempCF = GET_FLAG(Context, NDR_RFLAG_CF);
if ((cnt & cntmask) == 1)
{
SET_FLAG(Context, NDR_RFLAG_OF, ND_MSB(dst.Size, dst.Value.Qwords[0]) ^
GET_FLAG(Context, NDR_RFLAG_CF));
GET_FLAG(Context, NDR_RFLAG_CF));
}
while (tempcnt != 0)
if (tempcnt != 0)
{
tempCF = ND_LSB(dst.Size, dst.Value.Qwords[0]);
dst.Value.Qwords[0] = (dst.Value.Qwords[0] >> 1) +
((ND_UINT64)GET_FLAG(Context, NDR_RFLAG_CF) << (dst.Size * 8 - 1));
SET_FLAG(Context, NDR_RFLAG_CF, tempCF);
tempcnt--;
// tempcnt is in range [1, dst bit width].
ND_UINT64 left = (tempcnt == bitwidth) ? 0 : (dst.Value.Qwords[0] >> tempcnt);
ND_UINT64 right = (tempcnt == 1) ? 0 : (dst.Value.Qwords[0] << (bitwidth - tempcnt + 1));
SET_FLAG(Context, NDR_RFLAG_CF, ND_GET_BIT(tempcnt - 1, dst.Value.Qwords[0]));
dst.Value.Qwords[0] = left | ((ND_UINT64)tempCF << (bitwidth - tempcnt)) | right;
}
}
else if (ND_INS_ROL == Context->Instruction.Instruction)
{
while (tempcnt != 0)
if (tempcnt != 0)
{
tempCF = ND_MSB(dst.Size, dst.Value.Qwords[0]);
dst.Value.Qwords[0] = (dst.Value.Qwords[0] << 1) + tempCF;
tempcnt--;
// tempcnt is in range [1, dst bit width - 1].
ND_UINT64 left = dst.Value.Qwords[0] << tempcnt;
ND_UINT64 right = dst.Value.Qwords[0] >> (bitwidth - tempcnt);
dst.Value.Qwords[0] = left | right;
}
if ((cnt & cntmask) != 0)
{
SET_FLAG(Context, NDR_RFLAG_CF, dst.Value.Qwords[0] & 1);
SET_FLAG(Context, NDR_RFLAG_CF, ND_LSB(dst.Size, dst.Value.Qwords[0]));
}
if ((cnt & cntmask) == 1)
{
SET_FLAG(Context, NDR_RFLAG_OF, ND_MSB(dst.Size, dst.Value.Qwords[0]) ^
GET_FLAG(Context, NDR_RFLAG_CF));
GET_FLAG(Context, NDR_RFLAG_CF));
}
}
else // ND_INS_ROR
{
while (tempcnt != 0)
if (tempcnt != 0)
{
tempCF = ND_LSB(dst.Size, dst.Value.Qwords[0]);
dst.Value.Qwords[0] = (dst.Value.Qwords[0] >> 1) + ((ND_UINT64)tempCF << (dst.Size * 8 - 1));
tempcnt--;
// tempcnt is in range [1, dst bit width - 1].
ND_UINT64 left = (dst.Value.Qwords[0] >> tempcnt);
ND_UINT64 right = (dst.Value.Qwords[0] << (bitwidth - tempcnt));
dst.Value.Qwords[0] = left | right;
}
if ((cnt & cntmask) != 0)
@ -2241,7 +2255,8 @@ ShemuEmulate(
if ((cnt & cntmask) == 1)
{
SET_FLAG(Context, NDR_RFLAG_OF, ND_MSB(dst.Size, dst.Value.Qwords[0]) ^ ND_GET_BIT(dst.Size * 8ULL - 2, dst.Value.Qwords[0]));
SET_FLAG(Context, NDR_RFLAG_OF, ND_MSB(dst.Size, dst.Value.Qwords[0]) ^
ND_GET_BIT(dst.Size * 8ULL - 2, dst.Value.Qwords[0]));
}
}