#include <stdint.h>
#include "config.h"

extern void scanKeyboard();
extern void writeVideo();
extern uint8_t readVideo();
extern uint8_t videoX;
extern uint8_t videoY;
extern uint8_t videoMode;
extern uint8_t videoA;

static int8_t ram[RAMSIZE + 1];
static int8_t rom[ROMSIZE + 1];

static uint8_t systemRegister;
static uint8_t keyboardResult;


uint8_t read6502(uint16_t address);
void write6502(uint16_t address, uint8_t value);


uint8_t read6502(uint16_t address){
	switch (address){
		case RAMLOC ... RAMLOC + RAMSIZE:
			return ram[address - RAMLOC];
			break;
			
		case ROMLOC ... ROMLOC + ROMSIZE:
			return rom[address - ROMLOC];
			break;
			
		case VIDADDRS ... VIDADDRS + PAGESIZE:
			if ((address - VIDADDRS) % 4 == 3) return readVideo();
			else return 0;
			break;
		
		case 0xBD00:
			scanKeyboard();
			return keyboardResult;
			break;
			
		default: return NOP;
	}
}

void write6502(uint16_t address, uint8_t value){
	switch (address){
		case RAMLOC ... RAMLOC + RAMSIZE:
			ram[address - RAMLOC] = value;
			break;
			
		case ROMLOC ... ROMLOC + ROMSIZE:
			rom[address - ROMLOC] = value;
			break;
			
		case VIDADDRS ... VIDADDRS + PAGESIZE:
			switch ((address - VIDADDRS) % 4){
				case 0:			/* Video X Register */
					videoX = value & 0b01111111;
					break;
				case 1:			/* Video Y Register */
					videoY = value;
					break;
				case 2:			/* Video M Register */
					videoMode = value;
					break;
				case 3:			/* Video A Register */
					videoA = value;
					writeVideo();
					break;
			}
			break;

		case 0xBC00:
			systemRegister = value;
			break;
		default: break;
	}
}