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X86: Handle rotate left with carry instructions that go all the way around or more.

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This commit is contained in:
Gabe Black 2009-08-05 03:02:28 -07:00
parent 3990445354
commit c4140d7d60
1 changed files with 9 additions and 6 deletions
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15
src/arch/x86/isa/microops/regop.isa
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@ -839,15 +839,16 @@ let {{
code = ''' code = '''
uint8_t shiftAmt = uint8_t shiftAmt =
(op2 & ((dataSize == 8) ? mask(6) : mask(5))); (op2 & ((dataSize == 8) ? mask(6) : mask(5)));
if(shiftAmt) uint8_t realShiftAmt = shiftAmt % (dataSize * 8 + 1);
if(realShiftAmt)
{ {
CCFlagBits flags = ccFlagBits; CCFlagBits flags = ccFlagBits;
uint64_t top = psrc1 << shiftAmt; uint64_t top = psrc1 << realShiftAmt;
uint64_t bottom = flags.cf << (shiftAmt - 1); uint64_t bottom = flags.cf << (realShiftAmt - 1);
if(shiftAmt > 1) if(shiftAmt > 1)
bottom |= bottom |=
bits(psrc1, dataSize * 8 - 1, bits(psrc1, dataSize * 8 - 1,
dataSize * 8 - shiftAmt + 1); dataSize * 8 - realShiftAmt + 1);
DestReg = merge(DestReg, top | bottom, dataSize); DestReg = merge(DestReg, top | bottom, dataSize);
} }
else else
@ -856,13 +857,15 @@ let {{
flag_code = ''' flag_code = '''
// If the shift amount is zero, no flags should be modified. // If the shift amount is zero, no flags should be modified.
if (shiftAmt) { if (shiftAmt) {
int origCFBit = (ccFlagBits & CFBit) ? 1 : 0;
//Zero out any flags we might modify. This way we only have to //Zero out any flags we might modify. This way we only have to
//worry about setting them. //worry about setting them.
ccFlagBits = ccFlagBits & ~(ext & (CFBit | ECFBit | OFBit)); ccFlagBits = ccFlagBits & ~(ext & (CFBit | ECFBit | OFBit));
int msb = bits(DestReg, dataSize * 8 - 1); int msb = bits(DestReg, dataSize * 8 - 1);
int CFBits = bits(SrcReg1, dataSize * 8 - shiftAmt); int CFBits = bits(SrcReg1, dataSize * 8 - realShiftAmt);
//If some combination of the CF bits need to be set, set them. //If some combination of the CF bits need to be set, set them.
if ((ext & (CFBit | ECFBit)) && CFBits) if ((ext & (CFBit | ECFBit)) &&
(realShiftAmt == 0) ? origCFBit : CFBits)
ccFlagBits = ccFlagBits | (ext & (CFBit | ECFBit)); ccFlagBits = ccFlagBits | (ext & (CFBit | ECFBit));
//Figure out what the OF bit should be. //Figure out what the OF bit should be.
if ((ext & OFBit) && (msb ^ CFBits)) if ((ext & OFBit) && (msb ^ CFBits))