From 5e2b0979020a8da8274d2d3f9c7968e40f98ceea Mon Sep 17 00:00:00 2001 From: alyosha-tas Date: Wed, 10 Jul 2019 19:30:17 -0400 Subject: [PATCH] MC6809: fix DAA --- .../CPUs/MC6800/Operations.cs | 39 +++++++++++-------- .../CPUs/MC6809/Operations.cs | 38 ++++++++++-------- 2 files changed, 45 insertions(+), 32 deletions(-) diff --git a/BizHawk.Emulation.Cores/CPUs/MC6800/Operations.cs b/BizHawk.Emulation.Cores/CPUs/MC6800/Operations.cs index 8deab1a975..1b2c0468db 100644 --- a/BizHawk.Emulation.Cores/CPUs/MC6800/Operations.cs +++ b/BizHawk.Emulation.Cores/CPUs/MC6800/Operations.cs @@ -108,6 +108,7 @@ namespace BizHawk.Emulation.Common.Components.MC6800 FlagZ = Regs[src] == 0; FlagV = false; FlagN = (Regs[src] & 0xFF) > 127; + FlagC = false; } public void CLR_Func(ushort src) @@ -371,28 +372,34 @@ namespace BizHawk.Emulation.Common.Components.MC6800 Regs[dest] = ans; } - // DA code courtesy of AWJ: http://forums.nesdev.com/viewtopic.php?f=20&t=15944 public void DA_Func(ushort src) { - byte a = (byte)Regs[src]; + int a = Regs[src]; - if (!FlagN) - { // after an addition, adjust if (half-)carry occurred or if result is out of bounds - if (FlagC || a > 0x99) { a += 0x60; FlagC = true; } - if (FlagH || (a & 0x0f) > 0x09) { a += 0x6; } + byte CF = 0; + if (FlagC || ((a & 0xF) > 9)) + { + CF = 6; + } + if (FlagC || (((a >> 4) & 0xF) > 9) || ((((a >> 4) & 0xF) > 8) && ((a & 0xF) > 9))) + { + CF |= (byte)(6 << 4); + } + + a += CF; + + if ((a > 0xFF) || FlagC) + { + FlagC = true; } else - { // after a subtraction, only adjust if (half-)carry occurred - if (FlagC) { a -= 0x60; } - if (FlagH) { a -= 0x6; } + { + FlagC = false; } - - a &= 0xFF; - - Regs[src] = a; - - FlagZ = a == 0; - FlagH = false; + Regs[src] = (byte)a; + FlagN = a > 127; + FlagZ = a == 0; + // FlagV is listed as undefined in the documentation } public void CMP16_Func(ushort dest, ushort src) diff --git a/BizHawk.Emulation.Cores/CPUs/MC6809/Operations.cs b/BizHawk.Emulation.Cores/CPUs/MC6809/Operations.cs index eb2f1de17a..7c971acba3 100644 --- a/BizHawk.Emulation.Cores/CPUs/MC6809/Operations.cs +++ b/BizHawk.Emulation.Cores/CPUs/MC6809/Operations.cs @@ -438,28 +438,34 @@ namespace BizHawk.Emulation.Common.Components.MC6809 Regs[dest] = ans; } - // DA code courtesy of AWJ: http://forums.nesdev.com/viewtopic.php?f=20&t=15944 public void DA_Func(ushort src) { - byte a = (byte)Regs[src]; + int a = Regs[src]; - if (!FlagN) - { // after an addition, adjust if (half-)carry occurred or if result is out of bounds - if (FlagC || a > 0x99) { a += 0x60; FlagC = true; } - if (FlagH || (a & 0x0f) > 0x09) { a += 0x6; } + byte CF = 0; + if (FlagC || ((a & 0xF) > 9)) + { + CF = 6; + } + if (FlagC || (((a >> 4) & 0xF) > 9) || ((((a >> 4) & 0xF) > 8) && ((a & 0xF) > 9))) + { + CF |= (byte)(6 << 4); + } + + a += CF; + + if ((a > 0xFF) || FlagC) + { + FlagC = true; } else - { // after a subtraction, only adjust if (half-)carry occurred - if (FlagC) { a -= 0x60; } - if (FlagH) { a -= 0x6; } + { + FlagC = false; } - - a &= 0xFF; - - Regs[src] = a; - - FlagZ = a == 0; - FlagH = false; + Regs[src] = (byte)a; + FlagN = a > 127; + FlagZ = a == 0; + // FlagV is listed as undefined in the documentation } // D register implied