mirror of https://github.com/bsnes-emu/bsnes.git
64 lines
1.2 KiB
C++
64 lines
1.2 KiB
C++
#include <md/md.hpp>
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namespace MegaDrive {
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CPU cpu;
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auto CPU::Enter() -> void {
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cpu.boot();
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while(true) scheduler.synchronize(), cpu.main();
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}
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auto CPU::boot() -> void {
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r.a[7] = read(1, 0) << 16 | read(1, 2) << 0;
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r.pc = read(1, 4) << 16 | read(1, 6) << 0;
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}
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auto CPU::main() -> void {
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instruction();
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}
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auto CPU::step(uint clocks) -> void {
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Thread::step(clocks);
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cycles += clocks;
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if(cycles >= frequency() / 60) {
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cycles = 0;
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scheduler.exit(Scheduler::Event::Frame);
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}
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}
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auto CPU::power() -> void {
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M68K::power();
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for(auto& byte : ram) byte = 0x00;
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}
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auto CPU::reset() -> void {
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M68K::reset();
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create(CPU::Enter, system.colorburst() * 15.0 / 7.0);
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cycles = 0;
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}
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auto CPU::read(bool word, uint24 addr) -> uint16 {
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if(addr < 0x400000) return cartridge.read(word, addr);
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if(addr < 0xe00000) return 0x0000;
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uint16 data = ram[addr & 65535];
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if(word) data = data << 8 | ram[addr + 1 & 65535];
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return data;
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}
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auto CPU::write(bool word, uint24 addr, uint16 data) -> void {
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if(addr < 0x400000) return cartridge.write(word, addr, data);
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if(addr < 0xe00000) return;
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if(!word) {
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ram[addr & 65535] = data;
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} else {
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ram[addr + 0 & 65535] = data >> 8;
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ram[addr + 1 & 65535] = data >> 0;
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}
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}
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}
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