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static uint8_t mapper_001_0_prg_rom_read(struct nes_state *state, uint32_t addr) {
struct mapper_001_0 *mapper = &state->mapper_data.m001_0;
if(addr >= 0x8000) {
if(addr < 0xc000) {
return mapper->prg_rom_0[addr & 0x3fff];
} else {
return mapper->prg_rom_1[addr & 0x3fff];
}
}
return 0;
}
static void mapper_001_0_prg_rom_write(struct nes_state *state, uint32_t addr, uint8_t value) {
struct mapper_001_0 *mapper = &state->mapper_data.m001_0;
printf("MMC1 write: addr=%04x val=%02x\n", addr, value);
if(addr < 0x8000) {
return;
}
if(value & 0x80) {
mapper->shift = 0;
mapper->shift_count = 0;
mapper->control |= 0x0c;
return;
}
mapper->shift |= (value & 1) << mapper->shift_count;
mapper->shift_count++;
if(mapper->shift_count == 5) {
uint8_t reg = (addr >> 13) & 3;
switch(reg) {
case 0: {
mapper->control = mapper->shift;
switch(mapper->control & 3) {
case 0: {
state->ines.mirroring = MIRROR_ONESCREEN_LOW;
} break;
case 1: {
state->ines.mirroring = MIRROR_ONESCREEN_HIGH;
} break;
case 2: {
state->ines.mirroring = MIRROR_VERTICAL;
} break;
case 3: {
state->ines.mirroring = MIRROR_HORIZONTAL;
} break;
}
} break;
case 1: {
mapper->chr_bank0 = mapper->shift;
mapper->chr_bank_0 = state->chr_rom + (mapper->chr_bank0 * 0x1000);
} break;
case 2: {
mapper->chr_bank1 = mapper->shift;
mapper->chr_bank_1 = state->chr_rom + (mapper->chr_bank1 * 0x1000);
} break;
case 3: {
mapper->prg_bank = mapper->shift & 0x0f;
if(mapper->control & 0x08) {
if(mapper->control & 0x04) {
mapper->prg_rom_0 = state->prg_rom;
mapper->prg_rom_1 = state->prg_rom + (mapper->prg_bank * 0x4000);
} else {
mapper->prg_rom_0 = state->prg_rom + (mapper->prg_bank * 0x4000);
mapper->prg_rom_1 = state->prg_rom + (state->ines.prg_size - 0x4000);
}
} else {
uint32_t base = (mapper->prg_bank & 0x0e) * 0x4000;
mapper->prg_rom_0 = state->prg_rom + base;
mapper->prg_rom_1 = state->prg_rom + base + 0x4000;
}
} break;
}
mapper->shift = 0;
mapper->shift_count = 0;
}
}
static uint8_t mapper_001_0_chr_read(struct nes_state *state, uint32_t addr) {
struct mapper_001_0 *mapper = &state->mapper_data.m001_0;
if(mapper->control & 0x10) {
if(addr < 0x1000) {
return mapper->chr_bank_0[addr & 0xfff];
} else {
return mapper->chr_bank_1[addr & 0xfff];
}
} else {
return mapper->chr_bank_0[addr & 0x1fff];
}
}
static void mapper_001_0_chr_write(struct nes_state *state, uint32_t addr, uint8_t value) {
state->chr_ram[addr] = value;
}
static uint8_t mapper_001_0_ciram_read(struct nes_state *state, uint32_t addr) {
// MMC1 can set mirroring mode dynamically via control register
switch(state->ines.mirroring) {
case MIRROR_ONESCREEN_LOW:
addr = addr & 0x3ff;
break;
case MIRROR_ONESCREEN_HIGH:
addr = 0x400 | (addr & 0x3ff);
break;
case MIRROR_HORIZONTAL: // Horizontal: NT0↔NT1, NT2↔NT3
addr = ((addr >> 1) & 0x400) | (addr & 0x3ff);
break;
case MIRROR_VERTICAL: // Vertical: NT0↔NT2, NT1↔NT3
addr = addr & 0x7ff;
break;
}
return state->ciram[addr];
}
static void mapper_001_0_ciram_write(struct nes_state *state, uint32_t addr, uint8_t value) {
// MMC1 can set mirroring mode dynamically via control register
switch(state->ines.mirroring) {
case MIRROR_ONESCREEN_LOW:
addr = addr & 0x3ff;
break;
case MIRROR_ONESCREEN_HIGH:
addr = 0x400 | (addr & 0x3ff);
break;
case MIRROR_HORIZONTAL: // Horizontal: NT0↔NT1, NT2↔NT3
addr = ((addr >> 1) & 0x400) | (addr & 0x3ff);
break;
case MIRROR_VERTICAL: // Vertical: NT0↔NT2, NT1↔NT3
addr = addr & 0x7ff;
break;
}
state->ciram[addr] = value;
}
static void mapper_001_0_init(struct nes_state *state) {
struct mapper_001_0 *mapper = &state->mapper_data.m001_0;
mapper->shift = 0;
mapper->shift_count = 0;
mapper->control = 0x0c;
mapper->prg_bank = 0;
mapper->chr_bank0 = 0;
mapper->chr_bank1 = 0;
mapper->prg_rom_0 = state->prg_rom;
mapper->prg_rom_1 = state->prg_rom + (state->ines.prg_size - 0x4000);
if(state->ines.chr_size) {
mapper->chr_bank_0 = state->chr_rom;
mapper->chr_bank_1 = state->chr_rom + 0x1000;
} else {
mapper->chr_bank_0 = state->chr_ram;
mapper->chr_bank_1 = state->chr_ram + 0x1000;
}
state->mapper_function.prg_rom_read = mapper_001_0_prg_rom_read;
state->mapper_function.prg_rom_write = mapper_001_0_prg_rom_write;
state->mapper_function.chr_read = mapper_001_0_chr_read;
state->mapper_function.chr_write = mapper_001_0_chr_write;
state->mapper_function.ciram_read = mapper_001_0_ciram_read;
state->mapper_function.ciram_write = mapper_001_0_ciram_write;
}
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