//this should only be called by PPU::PPUcounter::tick(n);
//allows stepping by more than the smallest unit of time
void PPUcounter::tick(unsigned clocks) {
status.hcounter += clocks;
if(status.hcounter >= lineclocks()) {
status.hcounter -= lineclocks();
vcounter_tick();
}
}
void PPU::enter() {
while(true) {
if(scheduler.sync == Scheduler::SynchronizeMode::All) {
scheduler.exit(Scheduler::ExitReason::SynchronizeEvent);
}
scanline();
if(vcounter() < display.height && vcounter()) {
add_clocks(512);
render_scanline();
add_clocks(lineclocks() - 512);
} else {
add_clocks(lineclocks());
}
}
}
//called by ppu.tick() when Hcounter=0
void CPU::scanline() {
status.lineclocks = lineclocks();
//forcefully sync S-CPU to other processors, in case chips are not communicating
synchronize_ppu();
synchronize_smp();
synchronize_coprocessor();
system.scanline();
if(vcounter() == 0) {
//HDMA init triggers once every frame
status.hdma_init_position = (cpu_version == 1 ? 12 + 8 - dma_counter() : 12 + dma_counter());
status.hdma_init_triggered = false;
status.auto_joypad_counter = 0;
}
//DRAM refresh occurs once every scanline
if(cpu_version == 2) status.dram_refresh_position = 530 + 8 - dma_counter();
status.dram_refreshed = false;
//HDMA triggers once every visible scanline
if(vcounter() <= (ppu.overscan() == false ? 224 : 239)) {
status.hdma_position = 1104;
status.hdma_triggered = false;
}
}
//this should only be called by CPU::PPUcounter::tick();
//keeps track of previous counter positions in history table
void PPUcounter::tick() {
status.hcounter += 2; //increment by smallest unit of time
if(status.hcounter >= 1360 && status.hcounter == lineclocks()) {
status.hcounter = 0;
vcounter_tick();
}
history.index = (history.index + 1) & 2047;
history.field [history.index] = status.field;
history.vcounter[history.index] = status.vcounter;
history.hcounter[history.index] = status.hcounter;
}
