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Initial commit to public repository.
This commit is contained in:
Josh Dersch
121
D/Memory/Memory.cs
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121
D/Memory/Memory.cs
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/*
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BSD 2-Clause License
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Copyright Vulcan Inc. 2017-2018 and Living Computer Museum + Labs 2018
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice, this
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list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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DISCLAIMED.IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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using D.Logging;
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using System;
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namespace D.Memory
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{
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/// <summary>
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/// Encapsulates the physical memory, with enough of an ECC implementation
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/// to allow diagnostics to pass.
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/// </summary>
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public class Memory
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{
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public Memory()
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{
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Reset();
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}
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public void Reset()
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{
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if (_memory == null || _memory.Length != Configuration.MemorySize * 1024)
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{
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_memory = new ushort[Configuration.MemorySize * 1024];
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_ecc = new byte[_memory.Length];
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}
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else if (_memory != null)
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{
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Array.Clear(_memory, 0, _memory.Length);
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Array.Clear(_ecc, 0, _ecc.Length);
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}
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}
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public int Size
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{
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get { return _memory.Length; }
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}
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public ushort ReadWord(int address, out bool valid)
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{
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if (address < _memory.Length)
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{
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ushort memWord = _memory[address];
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valid = _ecc[address] == CalculateECCSyndrome(memWord);
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return memWord;
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}
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else
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{
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valid = false;
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return 0;
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}
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}
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public void WriteWord(int address, ushort value)
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{
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if (address < _memory.Length)
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{
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WriteECC(address, value);
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_memory[address] = value;
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}
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else
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{
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if (Log.Enabled) Log.Write(LogComponent.MemoryAccess, "Write to nonexistent memory address 0x{0:x}", address);
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}
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}
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public void SetCheckBits(int invertBits)
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{
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_mctlInvert = invertBits;
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}
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private byte CalculateECCSyndrome(ushort word)
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{
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//
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// Not actually calculating an ECC syndrome here, as at the moment there are no
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// plans to emulate faulty memory, or the hardware to correct it.
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//
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return 0;
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}
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private void WriteECC(int address, ushort value)
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{
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//
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// Write the calculated ECC syndrome value with the bits specified by MCtl<-
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// inverted.
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//
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_ecc[address] = (byte)(CalculateECCSyndrome(value) ^ _mctlInvert);
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}
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private ushort[] _memory;
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private byte[] _ecc;
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private int _mctlInvert;
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}
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}
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156
D/Memory/MemoryController.cs
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156
D/Memory/MemoryController.cs
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@@ -0,0 +1,156 @@
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/*
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BSD 2-Clause License
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Copyright Vulcan Inc. 2017-2018 and Living Computer Museum + Labs 2018
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
|
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* Redistributions of source code must retain the above copyright notice, this
|
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list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
|
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DISCLAIMED.IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
|
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FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
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DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
|
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SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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using D.CP;
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using D.Logging;
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namespace D.Memory
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{
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public class MemoryController
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{
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public MemoryController()
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{
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_mem = new Memory();
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}
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public void Reset()
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{
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_mStatus = 0;
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_mar = 0;
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_md = 0;
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_mdValid = true;
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_mem.Reset();
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}
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public ushort MStatus
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{
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get { return _mStatus; }
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}
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public int MAR
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{
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get { return _mar; }
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}
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// Exposing memory for debugging purposes.
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public Memory DebugMemory
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{
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get { return _mem; }
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}
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/// <summary>
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/// Used for debugging.
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/// </summary>
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public ushort MD
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{
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get { return _md; }
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}
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public void SetMCtl(ushort value)
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{
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//
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// See HWRef, figure 18 (pg 55).
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// This is used to test syndrome bits or clear error logs.
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//
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if (Log.Enabled) Log.Write(LogType.Verbose, LogComponent.MemoryControl, "MCtl<-0x{0:x}", value);
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_mem.SetCheckBits((value & 0xff) >> 2);
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if ((value & 0x800) != 0)
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{
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// Clear error log for the task specified by bits [5..7].
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int task = (value & 0x700) >> 8;
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_mStatus &= (ushort)(~(0x80 >> task));
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}
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}
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public void LoadMAR(int address)
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{
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_mar = address;
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//
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// Pre-load the memory requested, so we can return
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// the original data in cases where MDR is written and MD is read in the same click.
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//
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_md = _mem.ReadWord(_mar, out _mdValid);
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if (Log.Enabled) Log.Write(LogType.Verbose, LogComponent.MemoryAccess, "MAR<-0x{0:x5}", address);
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}
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public void LoadMDR(ushort value)
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{
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//
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// Write the word to memory
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//
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_mem.WriteWord(_mar, value);
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if (Log.Enabled)
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{
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Log.Write(LogType.Verbose, LogComponent.MemoryAccess, "MDR<-0x{0:x4}", value);
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if (_mar >= 0x10000 && _mar < 0x20000)
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{
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Log.Write(LogType.Verbose, LogComponent.CPMap, "MAP 0x{0:x5} = {1:x4}", _mar, value);
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}
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}
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}
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public ushort ReadMD(TaskType task, out bool valid)
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{
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//
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// Return the data read in LoadMAR.
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//
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if (Log.Enabled) Log.Write(LogType.Verbose, LogComponent.MemoryAccess, "<-MD (0x{0:x4}) valid {1}", _md, _mdValid);
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valid = _mdValid;
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if (!valid)
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{
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if (Log.Enabled) Log.Write(LogComponent.MemoryAccess, "Read from nonexistent memory address 0x{0:x}", _mar);
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_mStatus |= (ushort)((0x80 >> (int)task)); // Set error bit for task
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_mStatus |= 0x100; // double-bit error.
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// TODO: set syndrome bits
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}
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else
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{
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// Clear single/double-bit errors (bits 6..7)
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_mStatus &= 0xfcff;
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}
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return _md;
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}
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private int _mar;
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private ushort _md;
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private bool _mdValid;
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private ushort _mStatus;
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private Memory _mem;
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}
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}
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