//	instructions.c
//	Definition of all instruction functions, handling effect of instruction and flags.

#include"instructions.h"

/*	TO DO

!!!!!!!! CHECK THAT idata.value IS USED ACROSS ALL FUNCTIONS, NOT VAL !!!!!!!!!!!!!!
						~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Fix all functions before performing testing

*/


AddData idata;

// Load and Store Instructions

void fLDA(Addressing addr, address val){
	acc = idata.value;
	SetFlagN(acc);
}

void fLDX(Addressing addr, address val){
	X = idata.value;
}

void fLDY(Addressing addr, address val){
	Y = idata.value;
}

void fSTA(Addressing addr, address val){
	SetMemory(idata.add, acc);
}

void fSTX(Addressing addr, address val){
	SetMemory(idata.add, X);
}

void fSTY(Addressing addr, address val){
	SetMemory(idata.add, Y);
}

// Arithmetic Instructions

void fADC(Addressing addr, address val){
	int buffer = (int)acc + idata.value;
	SetFlagV(buffer, acc);

	if (buffer > 255)
		flagSet(flag_C);
	else
		flagClear(flag_C);

	acc += idata.value;
	SetFlagN(acc);
	SetFlagZ(acc);
}

void fSBC(Addressing addr, address val){
	int buffer = acc - idata.value;
	SetFlagV(buffer, acc);

	if (buffer < 0)
		flagSet(flag_C);
	else
		flagClear(flag_C);

	acc -= idata.value;
	SetFlagN(acc);
	SetFlagZ(acc);
}

//Increment and Decrement Instructions

void fINC(Addressing addr, address val){
	byte a = GetMemory(idata.add);
	a++;
	SetMemory(idata.add, a);
	SetFlagN(Memory[idata.add]);
	SetFlagZ(Memory[idata.add]);
}

void fINX(Addressing addr, address val){
	X++;
	SetFlagN(X);
	SetFlagZ(X);
}

void fINY(Addressing addr, address val){
	Y++;
	SetFlagN(Y);
	SetFlagZ(Y);
}

void fDEC(Addressing addr, address val){
	byte a = GetMemory(idata.add);
	a--;
	SetMemory(idata.add, a);
	SetFlagN(Memory[idata.add]);
	SetFlagZ(Memory[idata.add]);
}

void fDEX(Addressing addr, address val){
	X--;
	SetFlagN(X);
	SetFlagZ(X);
}

void fDEY(Addressing addr, address val){
	Y--;
	SetFlagN(Y);
	SetFlagZ(Y);
}

// Logical Instructions

void fAND(Addressing addr, address val){
	acc &= idata.value;
	SetFlagN(acc);
	SetFlagZ(acc);
}

void fORA(Addressing addr, address val){
	acc |= idata.value;
	SetFlagN(acc);
	SetFlagZ(acc);
}

void fEOR(Addressing addr, address val){
	acc ^= idata.value;
	SetFlagN(acc);
	SetFlagZ(acc);
}

// Jump, Branch, Compare, and Test Bits

void fJMP(Addressing addr, address val){
	PC = val; PC -= 2;
}

void fBCC(Addressing addr, address val){
	if (getFlag(flag_C) == 0) PC += (char)val;
}

void fBCS(Addressing addr, address val){
	if (getFlag(flag_C) == 1) PC += (char)val;
}

void fBEQ(Addressing addr, address val){
	if (getFlag(flag_Z) == 1) PC += (char)val;
}

void fBNE(Addressing addr, address val){
	if (getFlag(flag_Z) == 0) PC += (char)val;
}

void fBMI(Addressing addr, address val){
	if (getFlag(flag_N) == 1) PC += (char)val;
}

void fBPL(Addressing addr, address val){
	if (getFlag(flag_N) == 0) PC += (char)val;
}

void fBVS(Addressing addr, address val){
	if (getFlag(flag_V) == 1) PC += (char)val;
}

void fBVC(Addressing addr, address val){
	if (getFlag(flag_V) == 0) PC += (char)val;
}

void fCMP(Addressing addr, address val){
	if (acc < idata.value){
		flagSet(flag_N);	flagClear(flag_Z);	flagClear(flag_C);
	}
	else if (acc == idata.value){
		flagClear(flag_N);	flagSet(flag_Z);	flagClear(flag_C);
	}
	else if (acc > idata.value){
		flagClear(flag_N);	flagClear(flag_Z);	flagSet(flag_C);
	}
}

void fCPX(Addressing addr, address val){
	if (X < idata.value){
		flagSet(flag_N);	flagClear(flag_Z);	flagClear(flag_C);
	}
	else if (X == idata.value){
		flagClear(flag_N);	flagSet(flag_Z);	flagClear(flag_C);
	}
	else if (X > idata.value){
		flagClear(flag_N);	flagClear(flag_Z);	flagSet(flag_C);
	}
}

void fCPY(Addressing addr, address val){
	if (Y < idata.value){
		flagSet(flag_N);	flagClear(flag_Z);	flagClear(flag_C);
	}
	else if (Y == idata.value){
		flagClear(flag_N);	flagSet(flag_Z);	flagClear(flag_C);
	}
	else if (Y > idata.value){
		flagClear(flag_N);	flagClear(flag_Z);	flagSet(flag_C);
	}
}

//NEED TO DOUBLE CHECK THIS INSTRUCTION
void fBIT(Addressing addr, address val){
	SetFlag(flag_N, (idata.value & flag_N)?1:0);
	SetFlag(flag_V, (idata.value & flag_V)?1:0);
	
	if (((idata.value & flag_N) & (idata.value & flag_V)) == 0) {
		flagSet(flag_Z);
	} else {
		flagSet(flag_Z);
	}
}

// Shift and Rotate Instructions

void fASL(Addressing addr, address val){
	SetFlag(flag_C, (idata.value & 0x80)?1:0);
	acc = (idata.value << 1);
	SetFlagN(acc);
	SetFlagZ(acc);
}

void fLSR(Addressing addr, address val){
	SetFlag(flag_C, (idata.value & 0x01));
	acc = (idata.value >> 1);
	SetFlagN(acc);
	SetFlagZ(acc);
}

void fROL(Addressing addr, address val){
	SetFlag(flag_C, (val & 0x80)?1:0);
	acc = (val << 1);
	acc |= (getFlag(flag_C)?1:0);
	SetFlagN(acc);
	SetFlagZ(acc);
}

void fROR(Addressing addr, address val){
	SetFlag(flag_C, (val & 0x01));
	acc = (val >> 1);
	acc |= (getFlag(flag_C)?0x80:0);
	SetFlagN(acc);
	SetFlagZ(acc);
}

// Transfer Instructions

void fTAX(Addressing addr, address val){
	X = acc;
	//SetFlagN(X);
	//SetFlagZ(X);
}

void fTAY(Addressing addr, address val){
	Y = acc;
	//SetFlagN(Y);
	//SetFlagZ(Y);
}

void fTXA(Addressing addr, address val){
	acc = X;
	SetFlagN(acc);
	SetFlagZ(acc);
}

void fTYA(Addressing addr, address val){
	acc = Y;
	SetFlagN(acc);
	SetFlagZ(acc);
}

// Stack Instructions

void fTSX(Addressing addr, address val){
	X = S;
}

void fTXS(Addressing addr, address val){
	S = X;
}

void fPHA(Addressing addr, address val){
	SetStack(acc);
}

void fPHP(Addressing addr, address val){
	SetStack(P);
}

void fPLA(Addressing addr, address val){
	acc = GetStack();
}

void fPLP(Addressing addr, address val){
	P = GetStack();
}

// Subroutine Instructions
// NEED TO FINISH THESE

void fJSR(Addressing addr, address val){
	SetStack((PC+3) >> 8);
	SetStack((PC+3) & 0x00FF);
	PC = idata.add;
}

void fRTS(Addressing addr, address val){
	PC  =  (address)(GetStack()) - 1;
	PC += ((address)(GetStack())) << 8;
}

void fRTI(Addressing addr, address val){
	P = GetStack(); //NEED TO FIX
	PC  = (address)(GetStack());
	PC += (address)(GetStack() << 8);
}

// Set/Reset Insutrctions

void fCLC(Addressing addr, address val){
	flagClear(flag_C);
}

void fCLD(Addressing addr, address val){
	flagClear(flag_D);
}

void fCLI(Addressing addr, address val){
	flagClear(flag_I);
}

void fCLV(Addressing addr, address val){
	flagClear(flag_V);
}

void fSEC(Addressing addr, address val){
	flagSet(flag_C);
}

void fSED(Addressing addr, address val){
	flagSet(flag_D);
}

void fSEI(Addressing addr, address val){
	flagSet(flag_I);
}

// NOP/BRK Instructions

void fNOP(Addressing addr, address val){
}

void fBRK(Addressing addr, address val){
	SetStack((((PC+2) & 0xFF00) >> 8));
	SetStack((PC+2) & 0x00FF);
	SetStack(P);
	PC = (address)(GetMemory(0xFFFE));
	PC += ((address)(GetMemory(0xFFFF)) << 8);
}