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io.c
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#include "nes.h"
uint8_t nes_cpu_read_null(uint16_t address) {
printf("NULL READ AT %04x\n", address);
exit(0);
return 0;
}
void nes_cpu_write_null(uint16_t address, uint8_t value) {
}
uint8_t nes_cpu_bad_read(uint16_t address) {
printf("CPU ERROR: BAD READ AT 0x%04x.\n\n", address);
exit(EXIT_FAILURE);
return 0;
}
void nes_cpu_bad_write(uint16_t address, uint8_t value) {
printf("CPU ERROR: BAD WRITE OF %i AT 0x%04x.\n\n", value, address);
exit(EXIT_FAILURE);
}
uint8_t nes_cpu_read_ram(uint16_t address) {
return nes.ram[address % NES_RAM_SIZE];
if (address >= 0x100 && address <= 0x200) { printf("ABORT: CPU TRIED TO ACCESS STACK\n"); exit(EXIT_FAILURE); }
}
void nes_cpu_write_ram(uint16_t address, uint8_t value) {
nes.ram[address % NES_RAM_SIZE] = value;
}
uint8_t nes_cpu_read_io(uint16_t address) {
switch (address) {
/* PPU 0x2000 - 0x2007 */
case 0x2000:
/* PPU CTL1 */
return ppu.ctl1;
break;
case 0x2001:
/* PPU CTL2 */
return ppu.ctl2;
break;
case 0x2002:
/* PPU SREG */
ppu.sreg ^= (1 << 6);
return ppu.sreg;
break;
case 0x2003:
/* PPU SPR-RAM LATCH */
break;
case 0x2004:
/* PPU SPR-RAM DATA */
break;
case 0x2005:
/* VRAM SCROLL */
break;
case 0x2006:
/* VRAM LATCH */
break;
case 0x2007:
/* VRAM DATA */
break;
/* APU 0x4000 - 0x4013 */
case 0x4000:
break;
case 0x4001:
break;
case 0x4002:
break;
case 0x4003:
break;
case 0x4004:
break;
case 0x4005:
break;
case 0x4006:
break;
case 0x4007:
break;
case 0x4008:
break;
case 0x4009:
break;
case 0x400a:
break;
case 0x400b:
break;
case 0x400c:
break;
case 0x400d:
break;
case 0x400e:
break;
case 0x400f:
break;
case 0x4010:
break;
case 0x4011:
break;
case 0x4012:
break;
case 0x4013:
break;
/* PPU SPR-RAM DMA 0x4014 */
case 0x4014:
/* SPR_RAM DMA */
break;
/* APU 0x4015 */
case 0x4015:
break;
/* Joypad 0x4016 - 0x4017 */
case 0x4016:
/* Controller A */
break;
case 0x4017:
/* Controller B */
break;
default:
printf("ABORT: IO read error at 0x%04x.\n\n", address);
exit(EXIT_FAILURE);
break;
}
return 0;
}
void nes_cpu_write_io(uint16_t address, uint8_t value) {
switch (address) {
/* PPU 0x2000 - 0x2007 */
case 0x2000:
/* PPU CTL1 */
ppu.ctl1 = value;
break;
case 0x2001:
/* PPU CTL2 */
ppu.ctl2 = value;
break;
case 0x2002:
/* PPU SREG */
ppu.sreg = value;
break;
case 0x2003:
/* PPU SPR-RAM LATCH */
break;
case 0x2004:
/* PPU SPR-RAM DATA */
break;
case 0x2005:
/* VRAM SCROLL */
break;
case 0x2006:
/* VRAM LATCH */
if (!ppu.latch0) ppu.vaddrlo = value;
else ppu.vaddrhi = value;
ppu.latch0 ^= 1;
break;
case 0x2007:
/* VRAM DATA */
ppu.write(((ppu.vaddrhi << 8) | (ppu.vaddrlo)), value);
break;
/* APU 0x4000 - 0x4013 */
case 0x4000:
break;
case 0x4001:
break;
case 0x4002:
break;
case 0x4003:
break;
case 0x4004:
break;
case 0x4005:
break;
case 0x4006:
break;
case 0x4007:
break;
case 0x4008:
break;
case 0x4009:
break;
case 0x400a:
break;
case 0x400b:
break;
case 0x400c:
break;
case 0x400d:
break;
case 0x400e:
break;
case 0x400f:
break;
case 0x4010:
break;
case 0x4011:
break;
case 0x4012:
break;
case 0x4013:
break;
/* PPU SPR-RAM DMA 0x4014 */
case 0x4014:
/* SPR_RAM DMA */
break;
/* APU 0x4015 */
case 0x4015:
break;
/* Joypad 0x4016 - 0x4017 */
case 0x4016:
/* Controller A */
break;
case 0x4017:
/* Controller B */
break;
default:
printf("ABORT: IO write error at 0x%04x.\n\n", address);
exit(EXIT_FAILURE);
break;
}
}
uint8_t nes_cpu_read_rom0(uint16_t address) {
return nes.rom0[address % NES_ROM0_SIZE];
}
void nes_cpu_write_rom0(uint16_t address, uint8_t value) {
nes.rom0[address % NES_ROM0_SIZE] = value;
}
uint8_t nes_cpu_read_rom1(uint16_t address) {
return nes.rom1[address % NES_ROM1_SIZE];
}
void nes_cpu_write_rom1(uint16_t address, uint8_t value) {
nes.rom1[address % NES_ROM1_SIZE] = value;
}
uint8_t (* nes_cpu_read[0x20])(uint16_t address) = {
/* ADDRESS 0x0000 - 0x0800 */
nes_cpu_read_ram,
nes_cpu_read_ram,
nes_cpu_read_ram,
nes_cpu_read_ram,
/* ADDRESS 0x2000 - 0x4020 */
nes_cpu_read_io,
nes_cpu_read_io,
nes_cpu_read_io,
nes_cpu_read_io,
nes_cpu_read_io,
/* ADDRESS 0x04020 - 0x8000 */
nes_cpu_read_null,
nes_cpu_read_null,
nes_cpu_read_null,
nes_cpu_read_null,
nes_cpu_read_null,
nes_cpu_read_null,
nes_cpu_read_null,
/* ADDRESS 0x8000 - 0xC000 */
nes_cpu_read_rom0,
nes_cpu_read_rom0,
nes_cpu_read_rom0,
nes_cpu_read_rom0,
nes_cpu_read_rom0,
nes_cpu_read_rom0,
nes_cpu_read_rom0,
nes_cpu_read_rom0,
/* ADDRESS 0xC000 - 0x10000 */
nes_cpu_read_rom1,
nes_cpu_read_rom1,
nes_cpu_read_rom1,
nes_cpu_read_rom1,
nes_cpu_read_rom1,
nes_cpu_read_rom1,
nes_cpu_read_rom1,
nes_cpu_read_rom1,
};
void (* nes_cpu_write[0x20])(uint16_t address, uint8_t value) = {
/* ADDRESS 0x0000 - 0x0800 */
nes_cpu_write_ram,
nes_cpu_write_ram,
nes_cpu_write_ram,
nes_cpu_write_ram,
/* ADDRESS 0x2000 - 0x4020 */
nes_cpu_write_io,
nes_cpu_write_io,
nes_cpu_write_io,
nes_cpu_write_io,
nes_cpu_write_io,
/* ADDRESS 0x04020 - 0x8000 */
nes_cpu_write_null,
nes_cpu_write_null,
nes_cpu_write_null,
nes_cpu_write_null,
nes_cpu_write_null,
nes_cpu_write_null,
nes_cpu_write_null,
/* ADDRESS 0x8000 - 0xC000 */
nes_cpu_write_rom0,
nes_cpu_write_rom0,
nes_cpu_write_rom0,
nes_cpu_write_rom0,
nes_cpu_write_rom0,
nes_cpu_write_rom0,
nes_cpu_write_rom0,
nes_cpu_write_rom0,
/* ADDRESS 0xC000 - 0x10000 */
nes_cpu_write_rom1,
nes_cpu_write_rom1,
nes_cpu_write_rom1,
nes_cpu_write_rom1,
nes_cpu_write_rom1,
nes_cpu_write_rom1,
nes_cpu_write_rom1,
nes_cpu_write_rom1,
};