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Added a slightly faulty but seemingly 'close' version of masking.

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This commit is contained in:
Thomas Harte 2017-03-19 18:28:06 -04:00
parent 6c161b1150
commit 321030bb44
1 changed files with 13 additions and 7 deletions
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20
Machines/Atari2600/Cartridges/CartridgePitfall2.hpp
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@ -47,14 +47,12 @@ class CartridgePitfall2: public Cartridge<CartridgePitfall2> {
*value = 0x00;
break;
case 0x1008: case 0x1009: case 0x100a: case 0x100b: case 0x100c: case 0x100d: case 0x100e: case 0x100f: {
uint16_t fetch_address = (featcher_address_[address & 7] & 2047) ^ 2047;
featcher_address_[address & 7]--;
*value = rom_[8192 + fetch_address];
} break;
case 0x1008: case 0x1009: case 0x100a: case 0x100b: case 0x100c: case 0x100d: case 0x100e: case 0x100f:
*value = rom_[8192 + address_for_counter(address & 7)];
break;
case 0x1010: case 0x1011: case 0x1012: case 0x1013: case 0x1014: case 0x1015: case 0x1016: case 0x1017:
*value = 0xff;
*value = rom_[8192 + address_for_counter(address & 7)] & mask_[address & 7];
break;
#pragma mark - Writes
@ -91,8 +89,16 @@ class CartridgePitfall2: public Cartridge<CartridgePitfall2> {
}
private:
inline uint16_t address_for_counter(int counter) {
uint16_t fetch_address = (featcher_address_[counter] & 2047) ^ 2047;
featcher_address_[counter]--;
if((featcher_address_[counter] & 0xff) == top_[counter]) mask_[counter] = 0xff;
if((featcher_address_[counter] & 0xff) == bottom_[counter]) mask_[counter] = 0x00;
return fetch_address;
}
uint16_t featcher_address_[8];
uint8_t top_[8], bottom_[8];
uint8_t top_[8], bottom_[8], mask_[8];
uint8_t music_mode_[3];
uint8_t random_number_generator_;
uint8_t *rom_ptr_;