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X86 : Standadized calculation of Carry flag, and added some notes

This commit is contained in:
PatrickvL 2017-11-19 17:00:51 +01:00
parent 8fb061e4b2
commit 3298ce1ed4
1 changed files with 6 additions and 4 deletions
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10
src/CxbxKrnl/EmuX86.cpp
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@ -793,10 +793,12 @@ inline bool ComputeParityInParallel(uint8_t v)
// EFLAGS Cross-Reference : http://datasheets.chipdb.org/Intel/x86/Intel%20Architecture/EFLAGS.PDF
// TODO : Use templates for these, so 8 and 16 bit versions will look at the correct bits
#define Calc_SF(result) (result >> 31) & 1
#define Calc_ZF(result) result == 0
#define Calc_AF(result) (result >> 3) & 1
#define Calc_PF(result) ComputeParityInParallel(static_cast<uint8_t>(result))
#define Calc_CF(result) (result >> 32) & 1 // TODO : Instead of looking at an actual overflow bit, use high bit of result xor dest xor src
bool EmuX86_Opcode_ADD(LPEXCEPTION_POINTERS e, _DInst& info)
{
@ -843,7 +845,7 @@ bool EmuX86_Opcode_ADD(LPEXCEPTION_POINTERS e, _DInst& info)
/*EMUX86_EFLAG_ZF*/Calc_ZF(result),
/*EMUX86_EFLAG_AF*/Calc_AF(result),
/*EMUX86_EFLAG_PF*/Calc_PF(result),
/*EMUX86_EFLAG_CF*/(result >> 32) & 1);
/*EMUX86_EFLAG_CF*/Calc_CF(result));
return true;
}
@ -935,7 +937,7 @@ bool EmuX86_Opcode_CMP(LPEXCEPTION_POINTERS e, _DInst& info)
/*EMUX86_EFLAG_ZF*/Calc_ZF(result),
/*EMUX86_EFLAG_AF*/Calc_AF(result),
/*EMUX86_EFLAG_PF*/Calc_PF(result),
/*EMUX86_EFLAG_CF*/(result >> 32) & 1);
/*EMUX86_EFLAG_CF*/Calc_CF(result));
return true;
}
@ -975,7 +977,7 @@ bool EmuX86_Opcode_CMPXCHG(LPEXCEPTION_POINTERS e, _DInst& info)
/*EMUX86_EFLAG_ZF*/Calc_ZF(result),
/*EMUX86_EFLAG_AF*/Calc_AF(result),
/*EMUX86_EFLAG_PF*/Calc_PF(result),
/*EMUX86_EFLAG_CF*/(result >> 32) & 1);
/*EMUX86_EFLAG_CF*/Calc_CF(result));
return true;
}
@ -1082,7 +1084,7 @@ bool EmuX86_Opcode_SUB(LPEXCEPTION_POINTERS e, _DInst& info)
/*EMUX86_EFLAG_ZF*/Calc_ZF(result),
/*EMUX86_EFLAG_AF*/Calc_AF(result),
/*EMUX86_EFLAG_PF*/Calc_PF(result),
/*EMUX86_EFLAG_CF*/(result >> 32) & 1);
/*EMUX86_EFLAG_CF*/Calc_CF(result));
return true;
}