#include "opcode.h"
#include <stdint.h>
uint64_t a; /* Accumulator. */
uint64_t y; /* Y index. */
uint64_t x; /* X index. */
uint8_t crt; /* Current Running Threads. */
uint64_t pc[8]; /* Program counter. */
uint64_t ps; /* Processor status. */

int alu(uint8_t opcode, uint64_t value) {
	uint64_t sum;
	uint8_t carry = 0, vf = 0;
	switch(opcode) {
		/* Add with carry. */
		case ADC:
			sum = a+value+carry;
			vf = (~(a^value) & (a^sum & 0x80));
			carry = (sum < value) ? 1 : 0;
			a |= sum;
			break;
		/* Subtract with carry. */
		case SBC:
			sum = a-value-!carry;
			vf = (a^value) & (a^sum) & 0x80;
			carry = (sum > value) ? 1 : 0;
			a |= sum;
			break;
		/* Multiply with accumulator. */
		case MUL:
			sum = a*value+carry;
			vf = (~(a^value) & (a^sum & 0x80));
			carry = (sum < value) ? 1 : 0;
			a |= sum;
			break;
		/* Divide with accumulator. */
		case DIV:
			sum = a/value-!carry;
			vf = (a^value) & (a^sum) & 0x80;
			carry = (sum > value) ? 1 : 0;
			a |= sum;
			break;
		/* Bitwise AND. */
		case AND:
		case AAY:
		case AAX:
			a &= value;
			if (opcode == AAY)
				y &= value;
			if (opcode == AAX)
				x &= value;
			break;
		case ANY:
			y &= value;
			break;
		case ANX:
			x &= value;
			break;
		/* Bitwise OR. */
		case ORA:
		case OAY:
		case OAX:
			a |= value;
			if (opcode == OAY)
				y |= value;
			if (opcode == OAX)
				x |= value;
			break;
		case ORY:
			y |= value;
			break;
		case ORX:
			x |= value;
			break;
		/* Bitwise Exclusive OR. */
		case XOR:
		case XAY:
		case XAX:
			a ^= value;
			if (opcode == XAY)
				y ^= value;
			if (opcode == XAX)
				x ^= value;
			break;
		case XRY:
			y ^= value;
			break;
		case XRX:
			x ^= value;
			break;
		/* Shift accumulator left. */
		case SLA:
			a <<= value;
			break;
		/* Shift accumulator right. */
		case SRA:
			a >>= value;
			break;
		/* Rotate accumulator left. */
		case ROL:
			(a << value) | (a >> (64-value));
			break;
		/* Rotate accumulator right. */
		case ROR:
			(a >> value) | (a << (64-value));
			break;
	}
	ps |= vf;
	ps |= carry;
	return 1;
}

int threads(uint8_t opcode, uint64_t value) {
	uint8_t t = value & 0xFF; /* This tells the CPU, which threads to start, or end. */
	switch(opcode) {
		/* Start Thread. */
		case STT:
			crt |= t;
			for (uint8_t i = 0; i < 8; i++)
				if ((t >> i) & 1)
					pc[i] = value >> 8;
			break;
		/* End Thread. */
		case ENT:
			crt &= ~t;
			for (uint8_t i = 0; i < 8; i++)
				if ((t >> i) & 1)
					pc[i] = 0;
			break;
	}
}

int branch(uint8_t opcode, uint64_t value, uint8_t thread) {
			switch (opcode) {
				/* Jump. */
				case JMP:
					pc[thread] = value;
					break;
				/* Jump to subroutine. */
				case JSR:
					pc[thread] = value;
					pushaddr(value);
					break;
				/* Return from subroutine. */
				case RTS:
					pulladdr();
					break;
			}
	}
}