mirror of https://github.com/bsnes-emu/bsnes.git
81 lines
1.6 KiB
C++
81 lines
1.6 KiB
C++
struct VRC1 : Chip {
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uint4 prg_bank[3];
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uint4 chr_banklo[2];
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bool chr_bankhi[2];
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bool mirror;
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unsigned prg_addr(unsigned addr) const {
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unsigned bank = 0x0f;
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if((addr & 0xe000) == 0x8000) bank = prg_bank[0];
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if((addr & 0xe000) == 0xa000) bank = prg_bank[1];
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if((addr & 0xe000) == 0xc000) bank = prg_bank[2];
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return (bank * 0x2000) + (addr & 0x1fff);
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}
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unsigned chr_addr(unsigned addr) const {
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unsigned bank = chr_banklo[(bool)(addr & 0x1000)];
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bank |= chr_bankhi[(bool)(addr & 0x1000)] << 4;
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return (bank * 0x1000) + (addr & 0x0fff);
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}
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unsigned ciram_addr(unsigned addr) const {
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switch(mirror) {
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case 0: return ((addr & 0x0400) >> 0) | (addr & 0x03ff); //vertical mirroring
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case 1: return ((addr & 0x0800) >> 1) | (addr & 0x03ff); //horizontal mirroring
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}
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throw;
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}
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void reg_write(unsigned addr, uint8 data) {
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switch(addr & 0xf000) {
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case 0x8000:
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prg_bank[0] = data & 0x0f;
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break;
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case 0x9000:
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chr_bankhi[1] = data & 0x04;
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chr_bankhi[0] = data & 0x02;
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mirror = data & 0x01;
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break;
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case 0xa000:
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prg_bank[1] = data & 0x0f;
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break;
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case 0xc000:
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prg_bank[2] = data & 0x0f;
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break;
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case 0xe000:
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chr_banklo[0] = data & 0x0f;
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break;
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case 0xf000:
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chr_banklo[1] = data & 0x0f;
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break;
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}
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}
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void power() {
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}
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void reset() {
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for(auto& n : prg_bank) n = 0;
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for(auto& n : chr_banklo) n = 0;
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for(auto& n : chr_bankhi) n = 0;
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mirror = 0;
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}
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void serialize(serializer& s) {
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for(auto& n : prg_bank) s.integer(n);
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for(auto& n : chr_banklo) s.integer(n);
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for(auto& n : chr_bankhi) s.integer(n);
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s.integer(mirror);
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}
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VRC1(Board& board) : Chip(board) {
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}
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};
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