quickdev16/tools/bsnes/ppu/counter.cpp
2009-05-12 22:17:42 +02:00

51 lines
1.4 KiB
C++
Executable File

#ifdef PPU_CPP
//wrappers to allow PPUcounter::tick()/tock() to be inlined
bool PPUcounter::region() const { return system.region() == System::NTSC ? 0 : 1; }
bool PPUcounter::interlace() const { return ppu.interlace(); }
void PPUcounter::scanline() { cpu.scanline(); }
//one PPU dot = 4 CPU clocks
//
//PPU dots 323 and 327 are 6 CPU clocks long.
//this does not apply to NTSC non-interlace scanline 240 on odd fields. this is
//because the PPU skips one dot to alter the color burst phase of the video signal.
//
//dot 323 range = { 1292, 1294, 1296 }
//dot 327 range = { 1310, 1312, 1314 }
uint16 PPUcounter::hdot() const {
if(region() == 0 && interlace() == false && vcounter() == 240 && field() == 1) {
return (hcounter() >> 2);
} else {
return (hcounter() - ((hcounter() > 1292) << 1) - ((hcounter() > 1310) << 1)) >> 2;
}
}
uint16 PPUcounter::lineclocks() const {
if(region() == 0 && interlace() == false && vcounter() == 240 && field() == 1) return 1360;
return 1364;
}
uint16 PPUcounter::ilineclocks() const {
if(region() == 0 && interlace() == false && ivcounter() == 240 && ifield() == 1) return 1360;
return 1364;
}
void PPUcounter::reset() {
status.field = 0;
status.vcounter = 0;
status.hcounter = 0;
history.index = 0;
history.ppudiff = 0;
for(unsigned i = 0; i < 2048; i++) {
history.field [i] = 0;
history.vcounter[i] = 0;
history.hcounter[i] = 0;
}
}
#endif