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Made a first, hacky, attempt at audio.
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@ -17,11 +17,13 @@ class CartridgePitfall2: public Cartridge<CartridgePitfall2> {
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Cartridge(rom),
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random_number_generator_(0),
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featcher_address_{0, 0, 0, 0, 0, 0, 0, 0},
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mask_{0, 0, 0, 0, 0, 0, 0, 0} {
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mask_{0, 0, 0, 0, 0, 0, 0, 0},
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cycles_since_audio_update_(0) {
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rom_ptr_ = rom_.data();
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}
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void perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value) {
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cycles_since_audio_update_++;
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address &= 0x1fff;
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if(!(address & 0x1000)) return;
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@ -43,9 +45,9 @@ class CartridgePitfall2: public Cartridge<CartridgePitfall2> {
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) & 1));
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break;
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// Music fetcher
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case 0x1005: case 0x1006: case 0x1007:
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*value = 0x00;
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*value = update_audio();
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printf("%01x ", *value);
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break;
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case 0x1008: case 0x1009: case 0x100a: case 0x100b: case 0x100c: case 0x100d: case 0x100e: case 0x100f:
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@ -99,11 +101,29 @@ class CartridgePitfall2: public Cartridge<CartridgePitfall2> {
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return fetch_address;
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}
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inline uint8_t update_audio() {
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unsigned int cycles_to_run_for = cycles_since_audio_update_ / 57;
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cycles_since_audio_update_ %= 57;
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int table_position = 0;
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for(int c = 0; c < 3; c++) {
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audio_channel_[c] = (audio_channel_[c] + cycles_to_run_for) % (top_[5 + c] ^ 0xff);
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if((featcher_address_[5 + c] & 0x1000) && ((audio_channel_[c] ^ 0xff) > bottom_[5 + c])) {
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table_position |= 0x4 >> c;
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}
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}
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static uint8_t level_table[8] = { 0x0, 0x4, 0x5, 0x9, 0x6, 0xa, 0xb, 0xf };
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return level_table[table_position];
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}
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uint16_t featcher_address_[8];
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uint8_t top_[8], bottom_[8], mask_[8];
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uint8_t music_mode_[3];
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uint8_t random_number_generator_;
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uint8_t *rom_ptr_;
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uint8_t audio_channel_[3];
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unsigned int cycles_since_audio_update_;
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};
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}
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