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M6532: Added a dedicated cycle count variable to fix a timer issue. 

TIA: Increment the M6532 cycle count when in wsync.
This commit is contained in:
pjgat09 2012-03-21 01:02:24 +00:00
parent 5e65c7e977
commit 5b5932696d
3 changed files with 19 additions and 5 deletions
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1
BizHawk.Emulation/Consoles/Atari/2600/Atari2600.Core.cs
View File

@ -142,6 +142,7 @@ namespace BizHawk
tia.execute(1); tia.execute(1);
tia.execute(1); tia.execute(1);
m6532.tick();
cpu.Execute(1); cpu.Execute(1);
if (cpu.PendingCycles <= 0) if (cpu.PendingCycles <= 0)
{ {

15
BizHawk.Emulation/Consoles/Atari/2600/M6532.cs
View File

@ -22,7 +22,7 @@ namespace BizHawk.Emulation.Consoles.Atari
public byte swchb = 0x0B; public byte swchb = 0x0B;
public bool resetOccured = false; public bool resetOccured = false;
public int totalCycles = 0;
public M6532(MOS6507 cpu, byte[] ram, Atari2600 core) public M6532(MOS6507 cpu, byte[] ram, Atari2600 core)
{ {
@ -35,6 +35,11 @@ namespace BizHawk.Emulation.Consoles.Atari
} }
public void tick()
{
totalCycles++;
}
public byte ReadMemory(ushort addr) public byte ReadMemory(ushort addr)
{ {
ushort maskedAddr; ushort maskedAddr;
@ -53,12 +58,12 @@ namespace BizHawk.Emulation.Consoles.Atari
Console.WriteLine("6532 timer read: " + maskedAddr.ToString("x")); Console.WriteLine("6532 timer read: " + maskedAddr.ToString("x"));
// Calculate the current value on the timer // Calculate the current value on the timer
int timerCurrentValue = timerFinishedCycles - Cpu.TotalExecutedCycles; int timerCurrentValue = timerFinishedCycles - totalCycles;
interruptTriggered = false; interruptTriggered = false;
// If the timer has not finished, shift the value down for the game // If the timer has not finished, shift the value down for the game
if (Cpu.TotalExecutedCycles < timerFinishedCycles) if (totalCycles < timerFinishedCycles)
{ {
return (byte)(((timerCurrentValue) >> timerShift) & 0xFF); return (byte)(((timerCurrentValue) >> timerShift) & 0xFF);
} }
@ -93,7 +98,7 @@ namespace BizHawk.Emulation.Consoles.Atari
} }
else if (maskedAddr == 0x05) // interrupt else if (maskedAddr == 0x05) // interrupt
{ {
if ((timerFinishedCycles - Cpu.TotalExecutedCycles >= 0)|| (interruptEnabled && interruptTriggered)) if ((timerFinishedCycles - totalCycles >= 0)|| (interruptEnabled && interruptTriggered))
{ {
return 0x00; return 0x00;
} }
@ -130,7 +135,7 @@ namespace BizHawk.Emulation.Consoles.Atari
timerStartValue = value << timerShift; timerStartValue = value << timerShift;
// Calculate when the timer will be finished // Calculate when the timer will be finished
timerFinishedCycles = timerStartValue + Cpu.TotalExecutedCycles; timerFinishedCycles = timerStartValue + totalCycles;
Console.WriteLine("6532 timer write: " + maskedAddr.ToString("x")); Console.WriteLine("6532 timer write: " + maskedAddr.ToString("x"));

8
BizHawk.Emulation/Consoles/Atari/2600/TIA.cs
View File

@ -719,9 +719,17 @@ namespace BizHawk.Emulation.Consoles.Atari
} }
else if (maskedAddr == 0x02) // WSYNC else if (maskedAddr == 0x02) // WSYNC
{ {
int count = 0;
while (hsyncCnt > 0) while (hsyncCnt > 0)
{ {
count++;
execute(1); execute(1);
// Add a cycle to the cpu every 3 TIA clocks (corrects timer error in M6532)
if (count % 3 == 0)
{
core.m6532.tick();
}
} }
} }
else if (maskedAddr == 0x04) // NUSIZ0 else if (maskedAddr == 0x04) // NUSIZ0