mirror of https://github.com/bsnes-emu/bsnes.git
54 lines
1.3 KiB
C++
54 lines
1.3 KiB
C++
auto CPU::timer_step(uint clocks) -> void {
|
|
for(auto c : range(clocks)) {
|
|
for(auto n : range(4)) {
|
|
auto& timer = regs.timer[n];
|
|
|
|
if(timer.pending) {
|
|
timer.pending = false;
|
|
if(timer.control.enable == 1) {
|
|
timer.period = timer.reload;
|
|
}
|
|
continue;
|
|
}
|
|
|
|
if(timer.control.enable == false || timer.control.cascade == true) continue;
|
|
|
|
static uint mask[] = {0, 63, 255, 1023};
|
|
if((regs.clock & mask[timer.control.frequency]) == 0) {
|
|
timer_increment(n);
|
|
}
|
|
}
|
|
|
|
regs.clock++;
|
|
}
|
|
}
|
|
|
|
auto CPU::timer_increment(uint n) -> void {
|
|
auto& timer = regs.timer[n];
|
|
if(++timer.period == 0) {
|
|
timer.period = timer.reload;
|
|
|
|
if(timer.control.irq) regs.irq.flag |= Interrupt::Timer0 << n;
|
|
|
|
if(apu.fifo[0].timer == n) timer_fifo_run(0);
|
|
if(apu.fifo[1].timer == n) timer_fifo_run(1);
|
|
|
|
if(n < 3 && regs.timer[n + 1].control.enable && regs.timer[n + 1].control.cascade) {
|
|
timer_increment(n + 1);
|
|
}
|
|
}
|
|
}
|
|
|
|
auto CPU::timer_fifo_run(uint n) -> void {
|
|
apu.fifo[n].read();
|
|
if(apu.fifo[n].size > 16) return;
|
|
|
|
auto& dma = regs.dma[1 + n];
|
|
if(dma.control.enable && dma.control.timingmode == 3) {
|
|
dma.pending = true;
|
|
dma.control.targetmode = 2;
|
|
dma.control.size = 1;
|
|
dma.run.length = 4;
|
|
}
|
|
}
|