mirror of https://github.com/bsnes-emu/bsnes.git
84 lines
1.8 KiB
C++
84 lines
1.8 KiB
C++
auto Cartridge::EEPROM::read(uint addr) -> bool {
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return data[addr >> 3] & 0x80 >> (addr & 7);
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}
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auto Cartridge::EEPROM::write(uint addr, bool bit) -> void {
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if(bit == 0) data[addr >> 3] &=~ (0x80 >> (addr & 7));
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if(bit == 1) data[addr >> 3] |= (0x80 >> (addr & 7));
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}
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auto Cartridge::EEPROM::read() -> bool {
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bool bit = 1;
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//EEPROM size auto-detection
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if(bits == 0 && mode == Mode::ReadAddress) {
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print("EEPROM address bits: ", --addressbits, "\n");
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bits = addressbits == 6 ? 6 : 14;
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size = 8192;
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mode = Mode::ReadData;
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offset = 0;
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//fallthrough
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}
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if(mode == Mode::ReadData) {
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if(offset >= 4) bit = read(address * 64 + (offset - 4));
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if(++offset == 68) mode = Mode::Wait;
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}
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return bit;
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}
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auto Cartridge::EEPROM::write(bool bit) -> void {
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if(mode == Mode::Wait) {
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if(bit == 1) mode = Mode::Command;
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}
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else if(mode == Mode::Command) {
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if(bit == 0) mode = Mode::WriteAddress;
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if(bit == 1) mode = Mode::ReadAddress;
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offset = 0;
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address = 0;
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addressbits = 0;
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}
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else if(mode == Mode::ReadAddress) {
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address = (address << 1) | bit;
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addressbits++;
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if(++offset == bits) {
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mode = Mode::ReadValidate;
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offset = 0;
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}
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}
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else if(mode == Mode::ReadValidate) {
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if(bit == 1); //invalid
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mode = Mode::ReadData;
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}
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else if(mode == Mode::WriteAddress) {
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address = (address << 1) | bit;
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if(++offset == bits) {
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mode = Mode::WriteData;
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offset = 0;
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}
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}
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else if(mode == Mode::WriteData) {
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write(address * 64 + offset, bit);
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if(++offset == 64) {
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mode = Mode::WriteValidate;
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}
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}
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else if(mode == Mode::WriteValidate) {
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if(bit == 1); //invalid
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mode = Mode::Wait;
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}
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}
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auto Cartridge::EEPROM::power() -> void {
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mode = Mode::Wait;
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offset = 0;
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address = 0;
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}
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