// Negate
static bool
neg(PPCEmuAssembler& a, Instruction instr)
{
a.mov(a.eax, a.ppcgpr[instr.rA]);
a.neg(a.eax);
a.mov(a.ppcgpr[instr.rD], a.eax);
if (instr.oe) {
a.mov(a.ecx, 0);
a.seto(a.ecx.r8());
// Reset overflow
a.mov(a.edx, a.ppcxer);
a.and_(a.edx, ~XERegisterBits::Overflow);
a.shiftTo(a.ecx, 0, XERegisterBits::Overflow);
a.or_(a.edx, a.ecx);
a.shiftTo(a.ecx, XERegisterBits::Overflow, XERegisterBits::StickyOV);
a.or_(a.edx, a.ecx);
a.mov(a.ppcxer, a.edx);
}
if (instr.rc) {
updateConditionRegister(a, a.eax, a.ecx, a.edx);
}
return true;
}
// Update cr0 with value
static void
updateConditionRegister(PPCEmuAssembler& a, const asmjit::X86GpReg& value, const asmjit::X86GpReg& tmp, const asmjit::X86GpReg& tmp2)
{
auto crtarget = 0;
auto crshift = (7 - crtarget) * 4;
a.mov(tmp, a.ppccr);
a.and_(tmp, ~(0xF << crshift));
a.cmp(value, 0);
a.lahf();
a.mov(tmp2, 0);
a.sete(tmp2.r8());
a.shl(tmp2, crshift + ConditionRegisterFlag::ZeroShift);
a.or_(tmp, tmp2);
a.sahf();
a.mov(tmp2, 0);
a.setg(tmp2.r8());
a.shl(tmp2, crshift + ConditionRegisterFlag::PositiveShift);
a.or_(tmp, tmp2);
a.sahf();
a.mov(tmp2, 0);
a.setl(tmp2.r8());
a.shl(tmp2, crshift + ConditionRegisterFlag::NegativeShift);
a.or_(tmp, tmp2);
a.mov(tmp2, a.ppcxer);
a.and_(tmp2, XERegisterBits::StickyOV);
a.shiftTo(tmp2, XERegisterBits::StickyOVShift, crshift + ConditionRegisterFlag::SummaryOverflowShift);
a.or_(tmp, tmp2);
a.mov(a.ppccr, tmp);
}
