Subtract A, r instruction for the z80 in a gameboy

gistfile1.cpp

void Instructions::do8bitSubRegToA(CPU* cpu, BYTE (Registers::*getRegFunc)()){
	BYTE lInitialValue = cpu->reg->getA();
	BYTE lToSub = (cpu->reg->*getRegFunc)();
	WORD lTotal = lInitialValue - lToSub;

	// If the lower nibble of the original value is less than the lower nibble of what we're subtracting, it'll need a half carry
	cpu->reg->setFlagH((lInitialValue & 0x0f) < (lToSub & 0x0f)? 1 : 0);

	// If the original value is less than we're subtracting it'll carry
	cpu->reg->setFlagC(lInitialValue < lToSub ? 1 : 0);

	// Mask the total value that can fit in the register
	cpu->reg->setFlagZ((lTotal & 0xff) ? 0 : 1);

	cpu->reg->setFlagN(1);

	cpu->reg->setA((BYTE)(lTotal & 0xff));

	cpu->clock.m += 1;
	cpu->clock.t += 4;
	cpu->reg->incPC();
}

void Instructions::do8bitSubCRegToA(CPU* cpu, BYTE (Registers::*getRegFunc)()){
	BYTE lInitialValue = cpu->reg->getA();
	BYTE lToSub = (cpu->reg->*getRegFunc)() - cpu->reg->getFlagC();
	WORD lTotal = lInitialValue - lToSub;

	// If the lower nibble of the original value is less than the lower nibble of what we're subtracting, it'll need a half carry
	cpu->reg->setFlagH((lInitialValue & 0x0f) < (lToSub & 0x0f)? 1 : 0);

	// If the original value is less than we're subtracting it'll carry
	cpu->reg->setFlagC(lInitialValue < lToSub ? 1 : 0);

	// Mask the total value that can fit in the register
	cpu->reg->setFlagZ((lTotal & 0xff) ? 0 : 1);

	cpu->reg->setFlagN(1);

	cpu->reg->setA((BYTE)(lTotal & 0xff));

	cpu->clock.m += 1;
	cpu->clock.t += 4;
	cpu->reg->incPC();
}