mirror of https://github.com/bsnes-emu/bsnes.git
129 lines
2.7 KiB
C++
129 lines
2.7 KiB
C++
struct MMC1 : Chip {
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MMC1(Board& board) : Chip(board) {
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revision = Revision::MMC1B2;
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}
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auto main() -> void {
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if(writedelay) writedelay--;
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tick();
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}
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auto prg_addr(uint addr) -> uint {
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bool region = addr & 0x4000;
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uint bank = (prg_bank & ~1) + region;
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if(prg_size) {
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bank = (region == 0 ? 0x0 : 0xf);
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if(region != prg_mode) bank = prg_bank;
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}
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return (bank << 14) | (addr & 0x3fff);
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}
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auto chr_addr(uint addr) -> uint {
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bool region = addr & 0x1000;
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uint bank = chr_bank[region];
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if(chr_mode == 0) bank = (chr_bank[0] & ~1) | region;
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return (bank << 12) | (addr & 0x0fff);
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}
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auto ciram_addr(uint addr) -> uint {
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switch(mirror) {
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case 0: return 0x0000 | (addr & 0x03ff);
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case 1: return 0x0400 | (addr & 0x03ff);
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case 2: return ((addr & 0x0400) >> 0) | (addr & 0x03ff);
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case 3: return ((addr & 0x0800) >> 1) | (addr & 0x03ff);
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}
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}
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auto mmio_write(uint addr, uint8 data) -> void {
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if(writedelay) return;
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writedelay = 2;
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if(data & 0x80) {
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shiftaddr = 0;
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prg_size = 1;
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prg_mode = 1;
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} else {
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shiftdata = ((data & 1) << 4) | (shiftdata >> 1);
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if(++shiftaddr == 5) {
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shiftaddr = 0;
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switch((addr >> 13) & 3) {
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case 0:
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chr_mode = (shiftdata & 0x10);
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prg_size = (shiftdata & 0x08);
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prg_mode = (shiftdata & 0x04);
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mirror = (shiftdata & 0x03);
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break;
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case 1:
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chr_bank[0] = (shiftdata & 0x1f);
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break;
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case 2:
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chr_bank[1] = (shiftdata & 0x1f);
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break;
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case 3:
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ram_disable = (shiftdata & 0x10);
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prg_bank = (shiftdata & 0x0f);
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break;
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}
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}
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}
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}
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auto power() -> void {
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}
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auto reset() -> void {
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writedelay = 0;
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shiftaddr = 0;
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shiftdata = 0;
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chr_mode = 0;
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prg_size = 1;
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prg_mode = 1;
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mirror = 0;
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chr_bank[0] = 0;
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chr_bank[1] = 1;
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ram_disable = 0;
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prg_bank = 0;
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}
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auto serialize(serializer& s) -> void {
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s.integer(writedelay);
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s.integer(shiftaddr);
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s.integer(shiftdata);
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s.integer(chr_mode);
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s.integer(prg_size);
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s.integer(prg_mode);
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s.integer(mirror);
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s.array(chr_bank);
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s.integer(ram_disable);
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s.integer(prg_bank);
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}
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enum class Revision : uint {
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MMC1,
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MMC1A,
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MMC1B1,
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MMC1B2,
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MMC1B3,
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MMC1C,
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} revision;
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uint writedelay;
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uint shiftaddr;
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uint shiftdata;
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bool chr_mode;
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bool prg_size; //0 = 32K, 1 = 16K
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bool prg_mode;
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uint2 mirror; //0 = first, 1 = second, 2 = vertical, 3 = horizontal
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uint5 chr_bank[2];
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bool ram_disable;
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uint4 prg_bank;
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};
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