mirror of https://github.com/bsnes-emu/bsnes.git
38 lines
1.1 KiB
C++
38 lines
1.1 KiB
C++
auto CPU::prefetch_sync(uint32 addr) -> void {
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if(addr == prefetch.addr) return;
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prefetch.addr = addr;
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prefetch.load = addr;
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prefetch.wait = bus_wait(Half | Nonsequential, prefetch.load);
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}
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auto CPU::prefetch_step(unsigned clocks) -> void {
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step(clocks);
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if(!regs.wait.control.prefetch || active.dma) return;
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while(!prefetch.full() && clocks--) {
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if(--prefetch.wait) continue;
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prefetch.slot[prefetch.load >> 1 & 7] = cartridge.read(Half, prefetch.load);
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prefetch.load += 2;
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prefetch.wait = bus_wait(Half | Sequential, prefetch.load);
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}
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}
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auto CPU::prefetch_wait() -> void {
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if(!regs.wait.control.prefetch || active.dma || prefetch.full()) return;
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prefetch_step(prefetch.wait);
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prefetch.wait = bus_wait(Half | Nonsequential, prefetch.load);
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}
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auto CPU::prefetch_read() -> uint16 {
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if(prefetch.empty()) prefetch_step(prefetch.wait);
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else prefetch_step(1);
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if(prefetch.full()) prefetch.wait = bus_wait(Half | Sequential, prefetch.load);
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uint16 half = prefetch.slot[prefetch.addr >> 1 & 7];
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prefetch.addr += 2;
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return half;
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}
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