byte IMemoryBus.Read(int address)
{
if (this.readBreakpointsArray.Length != 0)
{
for (int i = 0; i < this.readBreakpointsArray.Length; i++)
{
if (this.readBreakpointsArray[i].TargetAddress == address)
{
this.readBreakpointsArray[i].OnBreakpointHit();
}
}
}
IMemoryMappedDevice device = this.GetDeviceAtAddress(ref address);
if (device == null)
{
Debug.WriteLine("Read of unmapped address 0x{0,8:X8} on bus '{1}'!", address, this.Name);
return(4); // Uninitialized memory contents, generated by fair dice roll;
}
return(device.Read(address));
}
/// <summary>
/// Dispatches reads to memory mapped hardware (RAM, I/O)
/// </summary>
/// <param name="address"></param>
/// <returns></returns>
private ushort ReadFromBus(ushort address, TaskType task, bool extendedMemoryReference)
{
if (address <= Memory.RamTop)
{
// Main memory access; shortcut hashtable lookup for performance reasons.
return(_mainMemory.Read(address, task, extendedMemoryReference));
}
else
{
// Memory-mapped device access:
// Look up address in hash; if populated ask the device
// to return a value otherwise return 0.
IMemoryMappedDevice memoryMappedDevice = null;
if (_bus.TryGetValue(address, out memoryMappedDevice))
{
return(memoryMappedDevice.Read(address, task, extendedMemoryReference));
}
else
{
return(0);
}
}
}
