mirror of
https://github.com/TomHarte/CLK.git
synced 2024-12-26 09:29:45 +00:00
51 lines
1.3 KiB
C++
51 lines
1.3 KiB
C++
//
|
|
// CartridgeActivisionStack.h
|
|
// Clock Signal
|
|
//
|
|
// Created by Thomas Harte on 18/03/2017.
|
|
// Copyright © 2017 Thomas Harte. All rights reserved.
|
|
//
|
|
|
|
#ifndef Atari2600_CartridgeActivisionStack_hpp
|
|
#define Atari2600_CartridgeActivisionStack_hpp
|
|
|
|
namespace Atari2600 {
|
|
|
|
class CartridgeActivisionStack: public Cartridge<CartridgeActivisionStack> {
|
|
public:
|
|
CartridgeActivisionStack(const std::vector<uint8_t> &rom) :
|
|
Cartridge(rom),
|
|
last_opcode_(0x00) {
|
|
rom_ptr_ = rom_.data();
|
|
}
|
|
|
|
void perform_bus_operation(CPU::MOS6502::BusOperation operation, uint16_t address, uint8_t *value) {
|
|
if(!(address & 0x1000)) return;
|
|
|
|
// This is a bit of a hack; a real cartridge can't see either the sync or read lines, and can't see
|
|
// address line 13. Instead it looks for a pattern in recent address accesses that would imply an
|
|
// RST or JSR.
|
|
if(operation == CPU::MOS6502::BusOperation::ReadOpcode && (last_opcode_ == 0x20 || last_opcode_ == 0x60)) {
|
|
if(address & 0x2000) {
|
|
rom_ptr_ = rom_.data();
|
|
} else {
|
|
rom_ptr_ = rom_.data() + 4096;
|
|
}
|
|
}
|
|
|
|
if(isReadOperation(operation)) {
|
|
*value = rom_ptr_[address & 4095];
|
|
}
|
|
|
|
if(operation == CPU::MOS6502::BusOperation::ReadOpcode) last_opcode_ = *value;
|
|
}
|
|
|
|
private:
|
|
uint8_t *rom_ptr_;
|
|
uint8_t last_opcode_;
|
|
};
|
|
|
|
}
|
|
|
|
#endif /* Atari2600_CartridgeActivisionStack_hpp */
|