void virtual_push(asmjit::X86Assembler& a, MemoryMapper& m, T value) {
a.mov(REG_TMP, 0x0100);
// @CLEANUP TMP is rax, but we can't or with a larger register
a.add(asmjit::x86::al, REG_SP);
m.emitDynamicStore(a, REG_TMP, value);
a.dec(REG_SP);
}
void virtual_pop(asmjit::X86Assembler& a, MemoryMapper& m, T dst) {
a.inc(REG_SP);
a.mov(REG_TMP, 0x0100);
// @CLEANUP TMP is rax, but we can't or with a larger register
a.add(asmjit::x86::al, REG_SP);
m.emitDynamicLoad(a, REG_TMP, dst);
}
bool LDXImmInstr::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.mov(REG_X, this->m_value);
// Immediate mode knows the value at compile time, so just emit the right
// thing
if(this->m_value == 0)
a.bts(REG_S, S_ZERO);
else
a.btr(REG_S, S_ZERO);
return true;
}
bool RTS::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
// Use rbx because that's safe during a call
virtual_pop(a, m, asmjit::x86::bl);
a.shl(asmjit::x86::bx, 8);
virtual_pop(a, m, asmjit::x86::dl);
a.or_(asmjit::x86::bx, asmjit::x86::dx);
a.mov(asmjit::x86::rdi, asmjit::x86::rbx);
a.jmp((uint64_t)&jit_and_jump);
return false;
}
bool JSRAbsInstr::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
// Push the virtual PC to the stack
// @COMPLETENESS: This order is likely wrong!
virtual_push(a, m, static_cast<uint8_t>(next & 0xFF));
virtual_push(a, m, static_cast<uint8_t>(next >> 8));
a.mov(asmjit::x86::di, this->target);
a.jmp((uint64_t)&jit_and_jump);
return false;
}
static void emitDump(asmjit::X86Assembler& a) {
a.push(asmjit::x86::r10);
a.push(asmjit::x86::r11);
a.mov(asmjit::x86::dil, REG_A);
a.mov(asmjit::x86::sil, REG_X);
a.mov(asmjit::x86::dl, REG_Y);
a.mov(asmjit::x86::cl, REG_S);
a.call((uint64_t)&dump);
a.pop(asmjit::x86::r11);
a.pop(asmjit::x86::r10);
}
bool BEQRelInstr::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
auto NotSet = a.newLabel();
a.bt(REG_S, S_ZERO);
a.jnc(NotSet);
a.mov(asmjit::x86::di, this->next + this->target);
a.jmp((uint64_t)&jit_and_jump);
a.bind(NotSet);
a.mov(asmjit::x86::di, this->next);
a.jmp((uint64_t)&jit_and_jump);
return false;
}
bool BPLRelInstr::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
auto Set = a.newLabel();
a.bt(REG_S, S_NEGATIVE);
a.jc(Set);
a.mov(asmjit::x86::di, this->next + this->target);
a.jmp((uint64_t)&jit_and_jump);
a.bind(Set);
a.mov(asmjit::x86::di, this->next);
a.jmp((uint64_t)&jit_and_jump);
return false;
}
bool CLC::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.btr(REG_S, S_CARRY);
return true;
}
bool NOP::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.nop();
return true;
}
void RamMemoryBank::emitLoad(asmjit::X86Assembler& a, uint16_t addr, asmjit::X86Gp dest) {
auto temp = asmjit::x86::rax;
a.mov(temp, (uint64_t)this->memory.get() + addr);
a.mov(dest, asmjit::x86::byte_ptr(temp));
}
bool ANDImm::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.and_(REG_A, this->operand);
return true;
}
bool CLD::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.btr(REG_S, S_DECIMAL);
return true;
}
bool SEI::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.bts(REG_S, S_INTER_DISABLE);
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 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;
}
void RamMemoryBank::emitStore(asmjit::X86Assembler& a, uint16_t addr, asmjit::X86Gp src) {
auto temp = asmjit::x86::rax;
a.mov(temp, (uint64_t)this->memory.get() + addr);
a.mov(asmjit::x86::byte_ptr(temp), src);
}
bool JMPAbsInstr::exp(asmjit::X86Assembler& a, MemoryMapper& m) {
a.mov(asmjit::x86::di, this->m_target);
a.jmp((uint64_t)&jit_and_jump);
return false;
}