implemented decfsz Instruction

Co-authored-by: Darkress <30271678+DarkressX@users.noreply.github.com>
Reviewed-on: darkress/pic16f84-sim#11

de/darkress/pic16f84sim/Main.java

@@ -3,16 +3,25 @@ package de.darkress.pic16f84sim;
 import de.darkress.pic16f84sim.commands.Command;
 import de.darkress.pic16f84sim.decoder.CommandDecoder;
 import de.darkress.pic16f84sim.microcontroller.Memory;
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+
 import java.util.ArrayList;
 
 class Main
 {
     public static void main(String[] args) {
-        ArrayList<Command> program = new ArrayList<>();
-        Memory.workingRegister = 0xAA;
-        int input1 = 0x3AFF;
-        program.add(CommandDecoder.decode(input1));
-        program.get(0).execute();
 
+        ArrayList<Command> program = new ArrayList<>();
+        int input1 = 0x27FF;
+        program.add(CommandDecoder.decode(0x3011)); //Write 0x11 to W
+        Memory.setRegister(0x14, 0x01);
+        program.add(CommandDecoder.decode(0x0B94));
+        program.add(CommandDecoder.decode(0x0B94));
+        program.add(CommandDecoder.decode(0x0B94));
+        program.add(CommandDecoder.decode(0x3F05));
+        for(int i = 0; i < program.size(); i++)
+        {
+            program.get(ProgramCounter.getPc()).execute();
+        }
     }
 }

de/darkress/pic16f84sim/commands/Addlw.java

@@ -1,8 +1,9 @@
 package de.darkress.pic16f84sim.commands;
 
 import de.darkress.pic16f84sim.microcontroller.Memory;
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
 
-public class Addlw extends CommandUtils implements Command
+public class Addlw extends LiteralCommandUtils implements Command
 {
     private final int literal;
 
@@ -21,5 +22,6 @@ public class Addlw extends CommandUtils implements Command
         checkDigitCarryBit(literal);
 
         Memory.workingRegister = result % 256;
+        ProgramCounter.incPC();
     }
 }

de/darkress/pic16f84sim/commands/Addwf.java

@@ -0,0 +1,29 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.Memory;
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+
+public class Addwf extends FileRegisterCommandUtils implements Command
+{
+    private final int address;
+    private final boolean destinationBit;
+
+    public Addwf(int input)
+    {
+        address = input & 0x007F;
+        destinationBit = checkDestinationBit(input);
+    }
+
+    @Override
+    public void execute()
+    {
+        int result = Memory.getRegister(address) + Memory.workingRegister;
+
+        checkZeroBit(result);
+        checkCarryBit(result);
+        checkDigitCarryBit(address);
+
+        writeToDestination(destinationBit, address, result);
+        ProgramCounter.incPC();
+    }
+}

de/darkress/pic16f84sim/commands/Andlw.java

@@ -2,7 +2,7 @@ package de.darkress.pic16f84sim.commands;
 
 import de.darkress.pic16f84sim.microcontroller.Memory;
 
-public class Andlw extends CommandUtils implements Command
+public class Andlw extends LiteralCommandUtils implements Command
 {
     private final int literal;
 

de/darkress/pic16f84sim/commands/Andwf.java

@@ -0,0 +1,27 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.Memory;
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+
+public class Andwf extends FileRegisterCommandUtils implements Command
+{
+    private final int address;
+    private final boolean destinationBit;
+
+    public Andwf(int input)
+    {
+        address = input & 0x007F;
+        destinationBit = checkDestinationBit(input);
+    }
+
+    @Override
+    public void execute()
+    {
+        int result = Memory.getRegister(address) & Memory.workingRegister;
+
+        checkZeroBit(result);
+
+        writeToDestination(destinationBit, address, result);
+        ProgramCounter.incPC();
+    }
+}

de/darkress/pic16f84sim/commands/Call.java

@@ -0,0 +1,21 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+import de.darkress.pic16f84sim.microcontroller.Stack;
+
+public class Call extends LiteralCommandUtils implements Command
+{
+    private final int literal;
+
+    public Call(int input)
+    {
+        literal = input & 0x07FF;
+    }
+
+    @Override
+    public void execute()
+    {
+        Stack.push(ProgramCounter.getPc() + 1);
+        ProgramCounter.setPcFrom11BitLiteral(literal);
+    }
+}

de/darkress/pic16f84sim/commands/Comf.java

@@ -0,0 +1,27 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.Memory;
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+
+public class Comf extends FileRegisterCommandUtils implements Command
+{
+    private final int address;
+    private final boolean destinationBit;
+
+    public Comf(int input)
+    {
+        address = input & 0x007F;
+        destinationBit = checkDestinationBit(input);
+    }
+
+    @Override
+    public void execute()
+    {
+        int result = 255 - Memory.getRegister(address); // Get inverse of 8Bit value
+
+        checkZeroBit(result);
+
+        writeToDestination(destinationBit, address, result);
+        ProgramCounter.incPC();
+    }
+}

de/darkress/pic16f84sim/commands/Decf.java

@@ -0,0 +1,27 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.Memory;
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+
+public class Decf extends FileRegisterCommandUtils implements Command
+{
+    private final int address;
+    private final boolean destinationBit;
+
+    public Decf(int input)
+    {
+        address = input & 0x007F;
+        destinationBit = checkDestinationBit(input);
+    }
+
+    @Override
+    public void execute()
+    {
+        int result = Memory.getRegister(address) + 255; // Allow underflow
+
+        checkZeroBit(result);
+
+        writeToDestination(destinationBit, address, result % 256); // Catch underflow
+        ProgramCounter.incPC();
+    }
+}

de/darkress/pic16f84sim/commands/Decfsz.java

@@ -0,0 +1,33 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.Memory;
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+
+public class Decfsz extends FileRegisterCommandUtils implements Command
+{
+    private final int address;
+    private final boolean destinationBit;
+
+    public Decfsz(int input)
+    {
+        address = input & 0x007F;
+        destinationBit = checkDestinationBit(input);
+    }
+
+    @Override
+    public void execute()
+    {
+        int result = Memory.getRegister(address) + 255; // Allow underflow
+
+        checkZeroBit(result);
+
+        writeToDestination(destinationBit, address, result % 256); // Catch underflow
+
+        if((result % 256) == 0)
+        {
+            Nop nop = new Nop();
+            nop.execute();
+        }
+        ProgramCounter.incPC();
+    }
+}

de/darkress/pic16f84sim/commands/FileRegisterCommandUtils.java

@@ -0,0 +1,51 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.Memory;
+
+public class FileRegisterCommandUtils
+{
+    protected void checkZeroBit(int result)
+    {
+        if((result % 256) == 0){
+            Memory.setZeroBit();
+        } else{
+            Memory.clearZeroBit();
+        }
+    }
+
+    protected void checkCarryBit(int result)
+    {
+        if(result > 255){
+            Memory.setCarryBit();
+        } else{
+            Memory.clearCarryBit();
+        }
+    }
+
+    protected void checkDigitCarryBit(int address)
+    {
+        int literal = Memory.getRegister(address);
+        if(((Memory.workingRegister & 0x0F) + (literal & 0x0F)) > 15){
+            Memory.setDigitCarryBit();
+        } else{
+            Memory.clearDigitCarryBit();
+        }
+    }
+
+    protected void writeToDestination(boolean destinationBit, int fileAddress, int result)
+    {
+        if(destinationBit)
+        {
+            //Store in FileRegister
+            Memory.setRegister(fileAddress, result);
+        } else {
+            //Store in WRegister
+            Memory.workingRegister = result;
+        }
+    }
+
+    protected boolean checkDestinationBit(int input)
+    {
+        return (input & 0x0080) == 0x0080;
+    }
+}

de/darkress/pic16f84sim/commands/Goto.java

@@ -0,0 +1,19 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+
+public class Goto extends LiteralCommandUtils implements Command
+{
+    private final int literal;
+
+    public Goto(int input)
+    {
+        literal = input & 0x07FF;
+    }
+
+    @Override
+    public void execute()
+    {
+        ProgramCounter.setPcFrom11BitLiteral(literal);
+    }
+}

de/darkress/pic16f84sim/commands/Iorlw.java

@@ -2,7 +2,7 @@ package de.darkress.pic16f84sim.commands;
 
 import de.darkress.pic16f84sim.microcontroller.Memory;
 
-public class Iorlw extends CommandUtils implements Command
+public class Iorlw extends LiteralCommandUtils implements Command
 {
     private final int literal;
 

de/darkress/pic16f84sim/commands/LiteralCommandUtils.java

@@ -2,7 +2,7 @@ package de.darkress.pic16f84sim.commands;
 
 import de.darkress.pic16f84sim.microcontroller.Memory;
 
-public class CommandUtils
+public class LiteralCommandUtils
 {
     protected void checkZeroBit(int result)
     {

de/darkress/pic16f84sim/commands/Movlw.java

@@ -1,8 +1,9 @@
 package de.darkress.pic16f84sim.commands;
 
 import de.darkress.pic16f84sim.microcontroller.Memory;
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
 
-public class Movlw extends CommandUtils implements Command
+public class Movlw extends LiteralCommandUtils implements Command
 {
     private final int literal;
 
@@ -15,5 +16,6 @@ public class Movlw extends CommandUtils implements Command
     public void execute()
     {
         Memory.workingRegister = literal;
+        ProgramCounter.incPC();
     }
 }

de/darkress/pic16f84sim/commands/Nop.java

@@ -0,0 +1,14 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+
+public class Nop extends LiteralCommandUtils implements Command
+{
+
+    @Override
+    public void execute()
+    {
+        // Do nothing, just increment the PC
+        ProgramCounter.incPC();
+    }
+}

de/darkress/pic16f84sim/commands/Retlw.java

@@ -0,0 +1,22 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.Memory;
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+import de.darkress.pic16f84sim.microcontroller.Stack;
+
+public class Retlw extends LiteralCommandUtils implements Command
+{
+    private final int literal;
+
+    public Retlw(int input)
+    {
+        literal = input & 0x00FF;
+    }
+
+    @Override
+    public void execute()
+    {
+        Memory.workingRegister = literal;
+        ProgramCounter.setPcFromStack(Stack.pop());
+    }
+}

de/darkress/pic16f84sim/commands/Return.java

@@ -0,0 +1,13 @@
+package de.darkress.pic16f84sim.commands;
+
+import de.darkress.pic16f84sim.microcontroller.ProgramCounter;
+import de.darkress.pic16f84sim.microcontroller.Stack;
+
+public class Return extends LiteralCommandUtils implements Command
+{
+    @Override
+    public void execute()
+    {
+        ProgramCounter.setPcFromStack(Stack.pop());
+    }
+}

de/darkress/pic16f84sim/commands/Sublw.java

@@ -2,7 +2,7 @@ package de.darkress.pic16f84sim.commands;
 
 import de.darkress.pic16f84sim.microcontroller.Memory;
 
-public class Sublw extends CommandUtils implements Command
+public class Sublw extends LiteralCommandUtils implements Command
 {
     private final int literal;
 

de/darkress/pic16f84sim/commands/Xorlw.java

@@ -2,7 +2,7 @@ package de.darkress.pic16f84sim.commands;
 
 import de.darkress.pic16f84sim.microcontroller.Memory;
 
-public class Xorlw extends CommandUtils implements Command
+public class Xorlw extends LiteralCommandUtils implements Command
 {
     private final int literal;
 

de/darkress/pic16f84sim/decoder/CommandDecoder.java

@@ -9,20 +9,15 @@ public class CommandDecoder
         switch(input & 0x3F00)
         {
             case 0x700:
-                //addwf();
+                return new Addwf(input);
-                break;
             case 0x500:
-                //andwf();
+                return new Andwf(input);
-                break;
             case 0x900:
-                //comf();
+                return new Comf(input);
-                break;
             case 0x300:
-                //decf();
+                return new Decf(input);
-                break;
             case 0xB00:
-                //decfsz();
+                return new Decfsz(input);
-                break;
             case 0xA00:
                 //incf();
                 break;
@@ -100,11 +95,9 @@ public class CommandDecoder
         switch(input & 0x3800)
         {
             case 0x2000:
-                //call();
+                return new Call(input);
-                break;
             case 0x2800:
-                //goto();
+                return new Goto(input);
-                break;
         }
 
         switch(input & 0x3C00)
@@ -112,13 +105,12 @@ public class CommandDecoder
             case 0x3000:
                 return new Movlw(input);
             case 0x3400:
-                //retlw();
+                return new Retlw(input);
-                break;
         }
 
         if ((input | 0x0060) == 0x0060)
         {
-            //nop();
+            return new Nop();
         }
 
         if (input == 0x0064)
@@ -133,8 +125,7 @@ public class CommandDecoder
 
         if (input == 0x0008)
         {
-            //return();
+            return new Return();
-            //This is the function name. Do not mistake this for a normal return!
         }
 
         if (input == 0x0063)

de/darkress/pic16f84sim/microcontroller/Memory.java

@@ -59,6 +59,10 @@ public class Memory
         }
         memory[address] = data;
         memory[address + 128] = data; //Ensure data is written to both banks to simulate mapping
+        if(address == 0x2) //Check if PCL is destination
+        {
+            ProgramCounter.loadPc();
+        }
     }
 
     private static int getDataFromIndirectAddress(int address)
@@ -75,6 +79,10 @@ public class Memory
         }
         memory[address % 128] = data; // else: Registers.Registers which are mapped
         memory[address % 128 + 128] = data; //Ensure data is written to both banks to simulate mapping
+        if(address == 0x2) //Check if PCL is destination
+        {
+            ProgramCounter.loadPc();
+        }
     }
 
     private static int getRegisterBank()
@@ -91,6 +99,28 @@ public class Memory
         return memory[0x4];
     }
 
+    public static int getPCL()
+    {
+        return memory[0x2];
+    }
+
+    public static void setPCL(int data)
+    {
+        memory[0x2] = data;
+        memory[0x82] = data;
+    }
+
+    public static int getPCLATH()
+    {
+        return memory[0xA] & 0x1F;
+    }
+
+    public static void setPCLATH(int data)
+    {
+        memory[0xA] = data & 0x1F;
+        memory[0x8A] = data & 0x1F;
+    }
+
     public static boolean getZeroBit()
     {
         return (memory[0x03] & 0x04) == 0x04;
@@ -99,6 +129,7 @@ public class Memory
     public static void setZeroBit()
     {
         memory[0x03] |= 0x04;
+        memory[0x83] |= 0x04;
     }
 
     public static void clearZeroBit()
@@ -114,6 +145,7 @@ public class Memory
     public static void setDigitCarryBit()
     {
         memory[0x03] |= 0x02;
+        memory[0x83] |= 0x02;
     }
 
     public static void clearDigitCarryBit()
@@ -129,6 +161,7 @@ public class Memory
     public static void setCarryBit()
     {
         memory[0x03] |= 0x01;
+        memory[0x83] |= 0x01;
     }
 
     public static void clearCarryBit()

de/darkress/pic16f84sim/microcontroller/ProgramCounter.java

@@ -4,20 +4,36 @@ public class ProgramCounter
 
     //This class is not actual part of the µC. It is a storage for the current value of the PC
 {
-    private static int PC = 0;
+    private static int pc = 0;
 
-    public static int getPC()
+    public static int getPc()
     {
-        return PC;
+        return pc;
     }
 
-    public static void setPC(int PC)
+    public static void setPcFrom11BitLiteral(int data)
     {
-        ProgramCounter.PC = PC;
+        int pcl = data & 0x00FF;
+        int pch = Memory.getPCLATH();
+        pch = ((pch & 0xF8) <<8) + (data & 0x700);
+        Memory.setPCL(pcl);
+        pc = (pch) + pcl;
     }
 
-    public static void incPC()
+    public static void setPcFromStack(int stack)
     {
-        PC++;
+        pc = stack;
+        Memory.setPCL(pc & 0x00FF);
+    }
+
+    public static void loadPc()
+    {
+        pc = (Memory.getPCLATH() <<8) + Memory.getPCL();
+    }
+
+    public static void incPC() //is called after every instruction execution
+    {
+        pc++;
+        Memory.setPCL(pc & 0x00FF);
     }
 }

de/darkress/pic16f84sim/microcontroller/Stack.java

@@ -14,9 +14,8 @@ public class Stack
 
     public static int pop()
     {
-        int tmp = stack[stackPointer];
         pointPrevious();
-        return tmp;
+        return stack[stackPointer];
     }
 
     public static int peek()