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NESHawk: DMC timing on multiple write ocodes

This commit is contained in:
alyosha-tas 2021-06-28 14:17:41 -04:00
parent 37a6446996
commit 1aadfd1edf
2 changed files with 9 additions and 3 deletions
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4
src/BizHawk.Emulation.Cores/CPUs/MOS 6502X/Execute.cs
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@ -511,13 +511,13 @@ namespace BizHawk.Emulation.Cores.Components.M6502
private const int VOP_NUM = 264; private const int VOP_NUM = 264;
//opcode bytes.. theoretically redundant with the temp variables? who knows. //opcode bytes.. theoretically redundant with the temp variables? who knows.
private int opcode; public int opcode;
private byte opcode2, opcode3; private byte opcode2, opcode3;
private int ea, alu_temp; //cpu internal temp variables private int ea, alu_temp; //cpu internal temp variables
private int mi; //microcode index private int mi; //microcode index
private bool iflag_pending; //iflag must be stored after it is checked in some cases (CLI and SEI). private bool iflag_pending; //iflag must be stored after it is checked in some cases (CLI and SEI).
private bool rdy_freeze; //true if the CPU must be frozen public bool rdy_freeze; //true if the CPU must be frozen
//tracks whether an interrupt condition has popped up recently. //tracks whether an interrupt condition has popped up recently.
//not sure if this is real or not but it helps with the branch_irq_hack //not sure if this is real or not but it helps with the branch_irq_hack

6
src/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/NES.Core.cs
View File

@ -492,6 +492,12 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
dmc_realign = true; dmc_realign = true;
} }
// By this point the cpu should be frozen, if it is not, then we are in a multi-write opcode, add another cycle delay
if (!cpu.RDY && !cpu.rdy_freeze && ((cpu.TotalExecutedCycles & 1) == 1))
{
apu.dmc_dma_countdown+=2;
}
cpu.RDY = false; cpu.RDY = false;
dmc_dma_exec = true; dmc_dma_exec = true;
apu.dmc_dma_countdown--; apu.dmc_dma_countdown--;