mirror of https://github.com/bsnes-emu/bsnes.git
61 lines
1.6 KiB
C++
61 lines
1.6 KiB
C++
void CPU::dma_run() {
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for(unsigned n = 0; n < 4; n++) {
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auto& dma = regs.dma[n];
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if(dma.pending) {
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dma.pending = false;
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dma_transfer(dma);
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if(dma.control.irq) regs.irq.flag.dma[n] = 1;
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if(dma.control.drq && n == 3) regs.irq.flag.cartridge = 1;
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}
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}
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}
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void CPU::dma_transfer(Registers::DMA& dma) {
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unsigned size = dma.control.size ? Word : Half;
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unsigned seek = dma.control.size ? 4 : 2;
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sequential() = false;
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do {
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step(bus.speed(dma.run.source, size));
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uint32 word = bus.read(dma.run.source, size);
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step(bus.speed(dma.run.target, size));
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bus.write(dma.run.target, size, word);
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sequential() = true;
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switch(dma.control.sourcemode) {
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case 0: dma.run.source += seek; break;
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case 1: dma.run.source -= seek; break;
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}
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switch(dma.control.targetmode) {
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case 0: dma.run.target += seek; break;
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case 1: dma.run.target -= seek; break;
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case 3: dma.run.target += seek; break;
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}
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} while(--dma.run.length);
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sequential() = false;
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if(dma.control.targetmode == 3) dma.run.target = dma.target;
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if(dma.control.repeat == 1) dma.run.length = dma.length;
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if(dma.control.repeat == 0) dma.control.enable = false;
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}
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void CPU::dma_vblank() {
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for(auto& dma : regs.dma) {
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if(dma.control.enable && dma.control.timingmode == 1) dma.pending = true;
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}
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}
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void CPU::dma_hblank() {
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for(auto& dma : regs.dma) {
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if(dma.control.enable && dma.control.timingmode == 2) dma.pending = true;
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}
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}
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void CPU::dma_hdma() {
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auto& dma = regs.dma[3];
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if(dma.control.enable && dma.control.timingmode == 3) dma.pending = true;
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}
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