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66 lines
1.6 KiB
C++
66 lines
1.6 KiB
C++
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//
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// CartridgePitfall2.h
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// Clock Signal
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//
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// Created by Thomas Harte on 18/03/2017.
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// Copyright © 2017 Thomas Harte. All rights reserved.
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//
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#ifndef Atari2600_CartridgePitfall2_hpp
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#define Atari2600_CartridgePitfall2_hpp
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namespace Atari2600 {
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class CartridgePitfall2: public Cartridge<CartridgePitfall2> {
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public:
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CartridgePitfall2(const std::vector<uint8_t> &rom) :
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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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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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address &= 0x1fff;
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if(!(address & 0x1000)) return;
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switch(address) {
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// The random number generator
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case 0x1000: case 0x1001: case 0x1002: case 0x1003:
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if(isReadOperation(operation)) {
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*value = random_number_generator_;
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}
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random_number_generator_ = (uint8_t)(
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(random_number_generator_ << 1) |
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~(( (random_number_generator_ >> 7) ^
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(random_number_generator_ >> 5) ^
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(random_number_generator_ >> 4) ^
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(random_number_generator_ >> 3)
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) & 1));
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break;
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case 0x1040: case 0x1041: case 0x1042: case 0x1043: case 0x1044: case 0x1045: case 0x1046: case 0x1047:
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// featcher_address_[address - 0x1040]
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break;
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case 0x1ff8: rom_ptr_ = rom_.data(); break;
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case 0x1ff9: rom_ptr_ = rom_.data() + 4096; break;
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default:
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if(isReadOperation(operation)) {
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*value = rom_ptr_[address & 4095];
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}
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break;
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}
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}
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private:
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uint16_t featcher_address_[8];
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uint8_t random_number_generator_;
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uint8_t *rom_ptr_;
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};
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}
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#endif /* Atari2600_CartridgePitfall2_hpp */
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