bool LDAAbsXInstr::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
auto temp = asmjit::x86::rax;
a.mov(temp, this->base);
a.add(temp, REG_X);
auto tmpPtr = asmjit::x86::byte_ptr(temp);
{
auto NotZero = a.newLabel();
auto Exit = a.newLabel();
a.cmp(tmpPtr, 0);
a.jne(NotZero);
// Value was 0
a.bts(REG_S, S_ZERO);
a.jmp(Exit);
// Value was not 0
a.bind(NotZero);
a.btr(REG_S, S_ZERO);
//No jmp required, just fall though
a.bind(Exit);
}
a.mov(REG_A, tmpPtr);
return true;
}
bool LDAImmInstr::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.mov(REG_A, this->value);
// Immediate mode knows the value at compile time, so just emit the right
// thing
if(this->value == 0)
a.bts(REG_S, S_ZERO);
else
a.btr(REG_S, S_ZERO);
if((this->value & 0x80) == 0)
a.btr(REG_S, S_NEGATIVE);
else
a.bts(REG_S, S_NEGATIVE);
return true;
}
bool CMPImm::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.cmp(REG_A, this->operand);
{
a.pushfd();
a.btr(REG_S, S_CARRY);
a.popfd();
auto End = a.newLabel();
a.jnc(End);
a.pushfd();
a.bts(REG_S, S_CARRY);
a.popfd();
a.bind(End);
}
{
a.pushfd();
a.btr(REG_S, S_ZERO);
a.popfd();
auto End = a.newLabel();
a.jne(End);
a.pushfd();
a.bts(REG_S, S_ZERO);
a.popfd();
a.bind(End);
}
{
a.pushfd();
a.btr(REG_S, S_NEGATIVE);
a.popfd();
auto End = a.newLabel();
a.jns(End);
a.pushfd();
a.bts(REG_S, S_NEGATIVE);
a.popfd();
a.bind(End);
}
return true;
}
bool BITZeroP::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
m.emitLoad(a, operand, asmjit::x86::al);
// @COMPLETENESS: We should check and set the S_ flags here before the and
a.push(asmjit::x86::rax);
a.and_(asmjit::x86::al, REG_A);
auto Zero = a.newLabel();
auto Exit = a.newLabel();
a.jz(Zero);
//Not zero
a.btr(REG_S, S_ZERO);
a.jmp(Exit);
a.bind(Zero);
a.bts(REG_S, S_ZERO);
a.bind(Exit);
a.pop(asmjit::x86::rax);
{
a.btr(REG_S, S_OVERFLOW);
a.bt(asmjit::x86::al, 6);
auto End = a.newLabel();
a.jnc(End);
a.bts(REG_S, S_OVERFLOW);
a.bind(End);
}
{
a.btr(REG_S, S_NEGATIVE);
a.bt(asmjit::x86::al, 7);
auto End = a.newLabel();
a.jnc(End);
a.bts(REG_S, S_NEGATIVE);
a.bind(End);
}
return true;
}
bool CLC::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.btr(REG_S, S_CARRY);
return true;
}
bool CLD::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.btr(REG_S, S_DECIMAL);
return true;
}