Sketching in the rest of the CPU

Contralto/CPU/ALU.cs

@@ -7,10 +7,21 @@ using System.Threading.Tasks;
 namespace Contralto.CPU
 {
     // From Alto Hardware Manual, Section 2.1
-
-
-
-    class ALU
+    static class ALU
     {
+        static ALU()
+        {
+            _lastCarry = 0;
+        }
+
+
+
+        public static ushort Execute(AluFunction fn, ushort a, ushort b)
+        {
+
+            return 0;
+        }
+
+        private static ushort _lastCarry;
     }
 }

Contralto/CPU/ConstantMemory.cs

@@ -0,0 +1,74 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Contralto.CPU
+{
+
+
+    static class ConstantMemory
+    {
+        static ConstantMemory()
+        {
+            Init();
+        }
+
+        private static void Init()
+        {
+            LoadConstants(_constantRoms);
+        }
+
+        public static ushort[] ConstantROM
+        {
+            get { return _constantRom; }
+        }
+
+        private static void LoadConstants(RomFile[] romInfo)
+        {
+            _constantRom = new ushort[256];
+
+            foreach (RomFile file in romInfo)
+            {
+                //
+                // Each file contains 256 bytes, each byte containing one nybble in the low 4 bits.
+                //
+                using (FileStream fs = new FileStream(Path.Combine("ROM", file.Filename), FileMode.Open, FileAccess.Read))
+                {
+                    int length = (int)fs.Length;
+                    if (length != 256)
+                    {
+                        throw new InvalidOperationException("ROM file should be 256 bytes in length");
+                    }
+
+                    byte[] data = new byte[fs.Length];
+                    fs.Read(data, 0, (int)fs.Length);
+
+                    // OR in the data
+                    for (int i = 0; i < length; i++)
+                    {
+                        _constantRom[file.StartingAddress + i] |= (ushort)((data[AddressMap(i)] & 0xf) << file.BitPosition);
+                    }
+                }
+            }
+        }
+
+        private static int AddressMap(int address)
+        {
+            int mappedAddress = (~address) & 0xff;
+            return mappedAddress;
+        }
+
+        private static RomFile[] _constantRoms =
+            {               
+                new RomFile("c0", 0x000, 12),
+                new RomFile("c1", 0x000, 8),
+                new RomFile("c2", 0x000, 4),
+                new RomFile("c3", 0x000, 0),                
+            };
+
+        private static UInt16[] _constantRom;
+    }
+}

Contralto/CPU/Shifter.cs

@@ -0,0 +1,81 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Contralto.CPU
+{
+    public enum ShifterOp
+    {
+        Invalid = 0,
+        None,
+        ShiftLeft,
+        ShiftRight,
+        RotateLeft,
+        RotateRight
+    }
+
+    public static class Shifter
+    {
+        static Shifter()
+        {
+            _op = ShifterOp.Invalid;
+        }
+
+        public static void SetOperation(ShifterOp op, int count)
+        {
+            _op = op;
+        }
+
+        public static ushort DoOperation(ushort input)
+        {
+            ushort output = 0;
+            switch(_op)
+            {
+                case ShifterOp.Invalid:
+                    throw new InvalidOperationException("Shifter op has not been set.");
+
+                case ShifterOp.None:
+                    output = input;
+                    break;
+
+                case ShifterOp.ShiftLeft:
+                    output = (ushort)(input << _count);
+                    break;
+
+                case ShifterOp.ShiftRight:
+                    output = (ushort)(input >> _count);
+                    break;
+
+                case ShifterOp.RotateLeft:
+                    // TODO: optimize, this is stupid
+                    output = input;
+                    for (int i = 0; i < _count; i++)
+                    {
+                        int c = (output & 0x8000) >> 15;
+                        output = (ushort)((output << 1) | c);
+                    }
+                    break;
+
+                case ShifterOp.RotateRight:
+                    // TODO: optimize, this is still stupid
+                    output = input;
+                    for (int i = 0; i < _count; i++)
+                    {
+                        int c = (output & 0x1) << 15;
+                        output = (ushort)((output >> 1) | c);
+                    }
+                    break;
+
+                default:
+                    throw new InvalidOperationException(String.Format("Unhandled shift operation {0}", _op));
+            }
+
+            return output;
+        }
+
+        private static ShifterOp _op;
+        private static int _count;
+    }
+}

Contralto/CPU/UCodeMemory.cs

@@ -32,7 +32,6 @@ namespace Contralto.CPU
         {            
             _uCodeRam = new UInt32[1024];
             LoadMicrocode(_uCodeRoms);
-            //_constantRom = LoadMicrocode(_constantRoms);
         }
 
         public static UInt32[] UCodeROM
@@ -40,6 +39,11 @@ namespace Contralto.CPU
             get { return _uCodeRom; }
         }
 
+        public static UInt32[] UCodeRAM
+        {
+            get { return _uCodeRam; }
+        }
+
         private static void LoadMicrocode(RomFile[] romInfo)
         {
             _uCodeRom = new UInt32[2048];
@@ -69,9 +73,8 @@ namespace Contralto.CPU
             }
 
             // Invert the requisite bits just to make things easier; the high bits of F1 and F2 and the Load L bit are inverted
-            // normally; we leave those alone.
+            // already; we leave those alone.
             const UInt32 invertedBitMask = 0xfff77bff;
-
             
             for(int i=0;i<_uCodeRom.Length;i++)
             {
@@ -82,24 +85,8 @@ namespace Contralto.CPU
         }
 
         private static int AddressMap(int address)
-        {
-            //
-            // For reasons lost to time, the address bits on the ucode PROMs are flipped
-            // (that is, address bit 9 on the PROM chip is connected to address bit 0 on the Alto's
-            // microcode address lines, and so on).  The address bits are also inverted, so that's fun too.
-            // We need to translate the 10-bit address appropriately by swapping the bits around.
-            //
-           int  mappedAddress = (~address) & 0x3ff;
-            /*
-            int mappedAddress = 0;
-            for(int i=0;i<10;i++)
-            {
-                if ((address & (1 << i)) != 0)
-                {
-                    mappedAddress |= (1 << (9 - i));
-                }
-            } */
-
+        {            
+            int  mappedAddress = (~address) & 0x3ff;
             return mappedAddress;
         }
 
@@ -124,16 +111,10 @@ namespace Contralto.CPU
             new RomFile("u70", 0x400, 8),
             new RomFile("u71", 0x400, 4),
             new RomFile("u72", 0x400, 0)
-        };
-
-        private static RomFile[] _constantRoms =
-        {
-
-        };
+        };        
 
         private static UInt32[] _uCodeRom;
-        private static UInt32[] _uCodeRam;
-        private static UInt16[] _constantRom;
+        private static UInt32[] _uCodeRam;        
 
 
     }

Contralto/Contralto.csproj

@@ -42,14 +42,28 @@
   </ItemGroup>
   <ItemGroup>
     <Compile Include="CPU\ALU.cs" />
+    <Compile Include="CPU\ConstantMemory.cs" />
     <Compile Include="CPU\CPU.cs" />
     <Compile Include="CPU\MicroInstruction.cs" />
+    <Compile Include="CPU\Shifter.cs" />
     <Compile Include="CPU\UCodeMemory.cs" />
     <Compile Include="Program.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="App.config" />
+    <None Include="ROM\C0">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+    <None Include="ROM\C1">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+    <None Include="ROM\C3">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
+    <None Include="ROM\C4">
+      <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+    </None>
     <None Include="ROM\U52">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>