public override void BusWrite(object sender, ushort address, byte value)
{
int linearAddress = 0;
bool isRam = false;
switch (address & 0xC000)
{
case 0x0000:
if (BootMode)
{
return;
}
linearAddress = address & 0x3FFF;
isRam = false;
break;
case 0x4000:
linearAddress = (address & 0x3FFF) | bank4000;
isRam = Bank4000IsRam;
break;
case 0x8000:
if (address < lowerPageAlwaysPresentLimit && memoryMapMode == 0)
{
isRam = true;
linearAddress = (address & 0x3FFF) | 0x4000;
break;
}
linearAddress = (address & 0x3FFF) | bank8000;
isRam = Bank8000IsRam;
break;
case 0xC000:
if (address >= upperPageAlawayPresentLimit && memoryMapMode == 0)
{
isRam = true;
linearAddress = (address & 0x3FFF);
break;
}
linearAddress = (address & 0x3FFF) | bankC000;
isRam = BankC000IsRam;
break;
}
Breakpoint bp = new Breakpoint()
{
Address = (ushort)(linearAddress & 0x3FFF),
IsRam = isRam,
Page = linearAddress >> 14,
Type = MemoryBreakpointType.Write
};
if (haveWriteBps && IsWriteBreakpoint(bp))
{
Cpu.BreakExecution();
}
if (isRam)
{
Ram.WriteByte(sender, linearAddress & 0x3FFFF, value);
}
else
{
if (!FlashWriteEnable)
{
return;
}
int highBits = ((1 << flashType) - 1) << 20;
if ((linearAddress & 0xF00000) == highBits)
{
highBits = linearAddress & 0xFFFFF;
if (highBits >= 0xB0000 && highBits < 0xC000 || highBits >= 0xFC000)
{
return;
}
}
Flash.WriteByte(sender, linearAddress, value);
}
}
/*
* 20.02
*
*/
// Value Boot Cert. Privileged Immutable
// 0 3F 3E 2C-2F, 3C-3F 2C-2F, 3F
// 1 7F 7E 6C-6F, 7C-7F 6C-6F, 7F
// 2 FF FE EC-EF, FC-FF EC-EF, FF
public override byte BusRead(object sender, ushort address)
{
int linearAddress = 0;
bool isRam = false;
// Compute linear address in RAM or flash
switch (address & 0xC000)
{
case 0x0000:
/*
* if (BootMode)
* return Flash.ReadByte(sender, address | 0xFFC000);
* else
* return Flash.ReadByte(sender, address);*/
isRam = false;
if (BootMode)
{
linearAddress = address | Flash.BootSector;
}
else
{
linearAddress = address;
}
break;
case 0x4000:
BootMode = false;
linearAddress = (address & 0x3FFF) | bank4000;
isRam = Bank4000IsRam;
break;
case 0x8000:
if (address < lowerPageAlwaysPresentLimit && memoryMapMode == 0)
{
isRam = true;
linearAddress = (address & 0x3FFF) | 0x4000;
break;
}
if (memoryMapMode == 1)
{
BootMode = false;
}
linearAddress = (address & 0x3FFF) | bank8000;
isRam = Bank8000IsRam;
break;
case 0xC000:
if (address >= upperPageAlawayPresentLimit && memoryMapMode == 0)
{
isRam = true;
linearAddress = (address & 0x3FFF);
break;
}
linearAddress = (address & 0x3FFF) | bankC000;
isRam = BankC000IsRam;
break;
}
Breakpoint bp = new Breakpoint()
{
Address = (ushort)(linearAddress & 0x3FFF),
IsRam = isRam,
Page = linearAddress >> 14,
Type = Cpu.M1 ? MemoryBreakpointType.Execution : MemoryBreakpointType.Read
};
if (Cpu.M1 && IsExecutionBreakpoint(bp))
{
Cpu.BreakExecution();
}
else if (haveReadBps && IsReadBreakpoint(bp))
{
Cpu.BreakExecution();
}
if (isRam)
{
// Check execution permissions: address must be within allowed limits, masked by RAM chip size
if (Cpu.M1 && sender is Z80Cpu)
{
if ((linearAddress & ramTypeMask) < ramLowerLimit || (linearAddress & ramTypeMask) >= ramUpperLimit)
{
Master.Reset();
}
}
return(Ram.ReadByte(sender, linearAddress & 0x3FFFF));
}
else
{
// Check execution permissions: address must be within allowed limits
if (Cpu.M1 && sender is Z80Cpu)
{
if ((linearAddress & flashTypeMask) >= flashLowerLimit && (linearAddress & flashTypeMask) < flashUpperLimit)
{
// . . . unless it's on a privileged page, in which case, execution is always allowed
if (!((((linearAddress >> 14) & 0xF) >= 0xC) && (((linearAddress >> 18) & 0x2) >= 2) && ((linearAddress >> 20) == (1 << flashType) - 1)))
{
Master.Reset();
}
}
}
// Check for censorship
int highBits = ((1 << flashType) - 1) << 20;
if ((linearAddress & 0xF00000) == highBits && !FlashWriteEnable)
{
highBits = linearAddress & 0xFFFFF;
if (highBits >= 0xF8000 && highBits < 0xFC000)
{
return(0xFF);
}
}
return(Flash.ReadByte(sender, linearAddress));
}
}