mirror of https://github.com/mlaux/gb6.git
95 lines
1.9 KiB
C
95 lines
1.9 KiB
C
#include <stdlib.h>
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#include <stdio.h>
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#include "types.h"
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#include "mbc.h"
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#include "dmg.h"
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#include "rom.h"
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static int mbc_noop_read(struct mbc *mbc, struct dmg *dmg, u16 addr, u8 *out_data)
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{
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return 0;
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}
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static int mbc_noop_write(struct mbc *mbc, struct dmg *dmg, u16 addr, u8 data)
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{
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return 0;
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}
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static int mbc1_read(struct mbc *mbc, struct dmg *dmg, u16 addr, u8 *out_data)
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{
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if (addr >= 0x4000 && addr <= 0x7fff) {
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int use_bank = mbc->rom_bank;
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if (!use_bank) {
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use_bank = 1;
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}
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*out_data = dmg->rom->data[0x4000 * use_bank + (addr & 0x3fff)];
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return 1;
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} else if (addr >= 0xa000 && addr <= 0xbfff) {
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if (mbc->ram_enabled) {
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*out_data = mbc->ram[0x2000 * mbc->ram_bank + (addr & 0x1fff)];
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} else {
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*out_data = 0xff;
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}
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return 1;
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}
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return 0;
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}
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static int mbc1_write(struct mbc *mbc, struct dmg *dmg, u16 addr, u8 data)
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{
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if (addr >= 0 && addr <= 0x1fff) {
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mbc->ram_enabled = (data & 0xf) == 0xa;
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return 1;
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} else if (addr >= 0x2000 && addr <= 0x3fff) {
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mbc->rom_bank = data & 0x1f;
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return 1;
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} else if (addr >= 0x4000 && addr <= 0x5fff) {
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mbc->ram_bank = data & 0x03;
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return 1;
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} else if (addr >= 0x6000 && addr <= 0x7fff) {
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//printf("sel %d\n", data);
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return 1;
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} else if (addr >= 0xa000 && addr <= 0xbfff) {
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if (mbc->ram_enabled) {
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mbc->ram[0x2000 * mbc->ram_bank + (addr & 0x1fff)] = data;
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return 1;
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}
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}
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return 0;
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}
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struct mbc mbc_noop = {
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mbc_noop_read,
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mbc_noop_write,
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};
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struct mbc mbc1 = {
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mbc1_read,
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mbc1_write,
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};
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struct mbc *mbc_new(int type)
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{
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switch (type) {
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case 0:
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return &mbc_noop;
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case 1:
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case 2:
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case 3:
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return &mbc1;
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}
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return NULL;
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}
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int mbc_read(struct mbc *mbc, struct dmg *dmg, u16 addr, u8 *out_data)
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{
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return mbc->read_fn(mbc, dmg, addr, out_data);
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}
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int mbc_write(struct mbc *mbc, struct dmg *dmg, u16 addr, u8 data)
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{
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return mbc->write_fn(mbc, dmg, addr, data);
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}
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