//	addressing.h
//	Contains definitions relevant to addressing, as well as fAddress() which returns time, length, value, and address for an instruction function call.
// Would like to refactor the code into something better, such as switch-case statements for the cycles calculation.

#include"addressing.h"


//Holds address of current instruction.
void* current_instruction;

address fAddressGetAddress(Addressing mode, short x) {
	switch(mode){
		case eImplied:
		case eIndirectAbsolute:
		case eRelative:
		case eImmediate:
		case eAccumulator:
			return 0x0000;
		case eAbsolute:
			return x;
		case eAbsoluteIndexedX:
			return x + X;
		case eAbsoluteIndexedY:
			return x + Y;
		case eZeroPage:
			return x & 0x00FF;
		case eZeroPageIndexedX:
			return ((x + X) & 0x00FF);
		case eZeroPageIndexedY:
			return ((x + Y) & 0x00FF);
		case eIndexedIndirect:
			return ((GetMemory(x+X+1))<<8) + (GetMemory(x+X));
		case eIndirectIndexed:
			return ((GetMemory(x+1))<<8) + (GetMemory(x)) + Y;
	}
}

int fAddressGetLength(Addressing mode){
	switch(mode){
		case eAbsolute: case eAbsoluteIndexedX: case eAbsoluteIndexedY:
			return 3;
		case eAccumulator: case eImplied:
			return 1;
		default:
			return 2;
	}
}

byte fAddressGetValue(Addressing mode, short x, address addr) {
	switch(mode){
		case eImplied:
		case eIndirectAbsolute:
			return 0;
		case eRelative: // TODO: MARKER FOR 3/12/2023
		case eImmediate:
			return x;
		case eAccumulator:
			return acc;
		default:
			return GetMemory(addr);
	}
}

int fAddressGetCycles(Addressing mode, short x, address addr) {
	int cycles;

	//case &fADC: case &fAND: case &fBIT: case &fCMP: case &fCPX: case &fCPY:	case &fEOR:	case &fLDA:
	//case &fLDX: case &fLDY: case &fORA: case &fSBC: case &fSTX: case &fSTY:

	if (	current_instruction ==  &fADC || current_instruction ==  &fAND || current_instruction == &fBIT || current_instruction ==  &fCMP || current_instruction ==  &fCPX
		||	current_instruction ==  &fCPY || current_instruction ==  &fEOR || current_instruction == &fLDA || current_instruction ==  &fLDX || current_instruction ==  &fLDY
		||	current_instruction ==  &fORA || current_instruction ==  &fSBC || current_instruction == &fSTX || current_instruction ==  &fSTY	){
		switch(mode){
			case eImmediate:
				cycles = 2; break;
			case eZeroPage:
				cycles = 3; break;
			case eZeroPageIndexedX: case eAbsolute: case eAbsoluteIndexedX: case eAbsoluteIndexedY:
				cycles = 4; break;
			case eIndexedIndirect:
				cycles = 6; break;
			case eIndirectIndexed:
				cycles = 5; break;
		}
	}

	//case &fASL: case &fDEC: case &fINC: case &fLSR: case &fROL: case &fROR:
	else if(	current_instruction ==  &fASL || current_instruction ==  &fDEC || current_instruction == &fINC
			||	current_instruction ==  &fLSR || current_instruction ==  &fROL || current_instruction == &fROR	){
		switch(mode){
			case eAccumulator:
				cycles = 2; break;
			case eZeroPage:
				cycles = 5; break;
			case eZeroPageIndexedX: case eAbsolute:
				cycles = 6; break;
			case eAbsoluteIndexedX:
				cycles = 7; break;
		}
	}

	//case &fSTA:
	else if  (current_instruction == &fSTA){
		switch(mode){
			case eZeroPage:
				cycles = 3; break;
			case eZeroPageIndexedX: case eAbsolute:
				cycles = 4; break;
			case eAbsoluteIndexedX: case eAbsoluteIndexedY:
				cycles = 5; break;
			case eIndexedIndirect: case eIndirectIndexed:
				cycles = 6; break;
		}
	}


	//case &fBRK:
	else if (current_instruction == &fBRK){
		cycles = 7;
	}


	//case &fRTI: case &fRTS: case &fJSR:
	else if (current_instruction == &fRTI || current_instruction == &fRTS || current_instruction == &fJSR){
		cycles = 6;
	}

	//case &fJMP:
	else if (current_instruction == &fJMP){
		cycles = 5;
	}

	//case &fPLA: case &fPLP:
	else if (current_instruction == &fPLA || current_instruction == &fPLP){
		cycles = 4;
	}

	//case &fPHA: case &fPHP:
	else if (current_instruction == &fPHA || current_instruction == &fPHP){
		cycles = 3;
	}

	else {
		cycles = 2;
	}


	// Page Boundary

	//case &fADC: case &fSBC: case &fLDA: case &fLDX: case &fLDY: case &fEOR: case &fAND: case &fORA: case &fCMP:
	if (	current_instruction ==  &fADC || current_instruction ==  &fSBC || current_instruction == &fLDA || current_instruction ==  &fLDX || current_instruction ==  &fLDY
		||	current_instruction ==  &fEOR || current_instruction ==  &fAND || current_instruction == &fORA || current_instruction ==  &fCMP ){
		switch(mode){
			case eAbsoluteIndexedX: 
				if ((x & 0xFF00) != ((x + X) & 0xFF00))
					cycles++;
				break;
			case eAbsoluteIndexedY: 
				if ((x & 0xFF00) != ((x + Y) & 0xFF00))
					cycles++;
				break;
			case eIndirectIndexed:
				if ((addr & 0xFF00) != (addr - Y & 0xFF00))
					cycles++;
				break;
		}
	}

	return cycles;
}

AddData fAddress(Addressing mode, short x) {
	AddData ret;
	ret.add    = fAddressGetAddress (mode, x);
	ret.value  = fAddressGetValue   (mode, x, ret.add);
	ret.length = fAddressGetLength  (mode);
	ret.cycles = fAddressGetCycles  (mode, x, ret.add);
	return ret;
}