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Fixing PAL timing bug 

Fixes Little Ninja Bros and Corvette ZR1 Challenge

Still needs investigation as seqeunce is 3,3,3,4,3 when it should be 3,3,3,3,4 but need a new test case.

Also added a note about DMA timing that needs to be investigated next.
This commit is contained in:
alyosha-tas 2016-05-05 12:04:51 -04:00
parent 75bb58d7e3
commit b8e5177d00
1 changed files with 10 additions and 7 deletions
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17
BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.Core.cs
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@ -284,12 +284,13 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
//PAL:
//0 15 30 45 60 -> 12 27 42 57 -> 9 24 39 54 -> 6 21 36 51 -> 3 18 33 48 -> 0
//sequence of ppu clocks per cpu clock: 4,3,3,3,3
//sequence of ppu clocks per cpu clock: 3,3,3,3,4
//at least it should be, but something is off with that (start up time?) so it is 3,3,3,4,3 for now
//NTSC:
//sequence of ppu clocks per cpu clock: 3
ByteBuffer cpu_sequence;
static ByteBuffer cpu_sequence_NTSC = new ByteBuffer(new byte[]{3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3});
static ByteBuffer cpu_sequence_PAL = new ByteBuffer(new byte[]{3,3,3,3,4,3,3,3,3,4,3,3,3,3,4,3,3,3,3,4,3,3,3,3,4,3,3,3,3,4,3,3,3,3,4,3,3,3,3,4});
static ByteBuffer cpu_sequence_NTSC = new ByteBuffer(new byte[]{3,3,3,3,3});
static ByteBuffer cpu_sequence_PAL = new ByteBuffer(new byte[]{3,3,3,4,3});
public int cpu_step, cpu_stepcounter, cpu_deadcounter;
#if VS2012
@ -301,7 +302,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
if (cpu_stepcounter == cpu_sequence[cpu_step])
{
cpu_step++;
cpu_step &= 31;
if(cpu_step == 5) cpu_step=0;
cpu_stepcounter = 0;
if (sprdma_countdown > 0)
@ -309,9 +310,11 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
sprdma_countdown--;
if (sprdma_countdown == 0)
{
//its weird that this is 514.. normally itd be 512 (and people would say its wrong) or 513 (and people would say its right)
//but 514 passes test 4-irq_and_dma
cpu_deadcounter += 514;
//its weird that this is 514.. normally itd be 512 (and people would say its wrong) or 513 (and people would say its right)
//but 514 passes test 4-irq_and_dma
// according to nesdev wiki, http://wiki.nesdev.com/w/index.php/PPU_OAM this is 513 on even cycles and 514 on odd cycles
// TODO: Implement that
cpu_deadcounter += 514;
}
}