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Add AAM and AAS.

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This commit is contained in:
Thomas Harte 2023-10-05 14:52:24 -04:00
parent 059f300500
commit 09b2cfad8a
1 changed files with 46 additions and 0 deletions
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46
InstructionSets/x86/Implementation/PerformImplementation.hpp
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@ -57,6 +57,50 @@ void aad(CPU::RegisterPair16 &ax, uint8_t imm, Status &status) {
status.parity = status.zero = ax.halves.low;
}
void aam(CPU::RegisterPair16 &ax, uint8_t imm, Status &status) {
/*
tempAL ← AL;
AH ← tempAL / imm8; (* imm8 is set to 0AH for the AAD mnemonic *)
AL ← tempAL MOD imm8;
*/
/*
The SF, ZF, and PF flags are set according to the result.
The OF, AF, and CF flags are undefined.
*/
ax.halves.high = ax.halves.low / imm;
ax.halves.low = ax.halves.low % imm;
status.sign = ax.halves.low & 0x80;
status.parity = status.zero = ax.halves.low;
}
void aas(CPU::RegisterPair16 &ax, Status &status) {
/*
IF ((AL AND 0FH) > 9) OR (AF = 1)
THEN
AL ← AL – 6;
AH ← AH – 1;
AF ← 1;
CF ← 1;
ELSE
CF ← 0;
AF ← 0;
FI;
AL ← AL AND 0FH;
*/
/*
The AF and CF flags are set to 1 if there is a decimal borrow;
otherwise, they are cleared to 0. The OF, SF, ZF, and PF flags are undefined.
*/
if((ax.halves.low & 0x0f) > 9 || status.auxiliary_carry) {
ax.halves.low -= 6;
--ax.halves.high;
status.auxiliary_carry = status.carry = 1;
} else {
status.auxiliary_carry = status.carry = 0;
}
ax.halves.low &= 0x0f;
}
}
template <
@ -73,6 +117,8 @@ template <
switch(operation) {
case Operation::AAA: Primitive::aaa(destination, status); break;
case Operation::AAD: Primitive::aad(destination, source.halves.low, status); break;
case Operation::AAM: Primitive::aam(destination, source.halves.low, status); break;
case Operation::AAS: Primitive::aas(destination, status); break;
}
(void)flow_controller;