Adds more instructions

app/build.gradle

@@ -21,6 +21,9 @@ android {
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'
     }
+    testOptions {
+        unitTests.returnDefaultValues = true
+    }
 }
 
 dependencies {

app/src/main/kotlin/android/emu6502/CPU.kt

@@ -35,6 +35,8 @@ class CPU(private val memory: Memory) {
       Pair(Instruction.LDY, LDY(this)),
       Pair(Instruction.STA, STA(memory, this)),
       Pair(Instruction.STX, STX(this)),
+      Pair(Instruction.TAX, TAX(this)),
+      Pair(Instruction.INX, INX(this)),
       Pair(Instruction.ORA, ORA(this))
 //      Pair(Instruction.BPL, BPL(this)),
 //      Pair(Instruction.BMI, BMI(this)),
@@ -62,10 +64,8 @@ class CPU(private val memory: Memory) {
 //      Pair(Instruction.JSR, JSR(this)),
 //      Pair(Instruction.LSR, LSR(this)),
 //      Pair(Instruction.NOP, NOP(this)),
-//      Pair(Instruction.TAX, TAX(this)),
 //      Pair(Instruction.TXA, TXA(this)),
 //      Pair(Instruction.DEX, DEX(this)),
-//      Pair(Instruction.INX, INX(this)),
 //      Pair(Instruction.TAY, TAY(this)),
 //      Pair(Instruction.TYA, TYA(this)),
 //      Pair(Instruction.DEY, DEY(this)),
@@ -94,7 +94,7 @@ class CPU(private val memory: Memory) {
         break
       }
     }
-    isRunning = false
+    stop()
     Log.i(TAG, "Program end at PC=$" + (PC - 1).toHexString() + ", A=$" + A.toHexString() +
                ", X=$" + X.toHexString() + ", Y=$" + Y.toHexString())
   }
@@ -107,12 +107,16 @@ class CPU(private val memory: Memory) {
       target.operation.function()
     } else {
       Log.e(TAG, "Address $" + PC.toHexString() + " - unknown opcode " + instruction.toHexString())
-      isRunning = false
+      stop()
     }
   }
 
+  fun stop() {
+    isRunning = false
+  }
+
    fun popByte(): Int {
-    return memory.get(PC++).and(0xff);
+    return memory.get(PC++).and(0xff)
   }
 
   private fun setRandomByte() {
@@ -123,20 +127,107 @@ class CPU(private val memory: Memory) {
     setSZFlagsForValue(A)
   }
 
+  fun setSZflagsForRegX() {
+    setSZFlagsForValue(X)
+  }
+
   private fun setSZFlagsForValue(value: Int) {
     if (value != 0) {
-      P = P.and(0xfd);
+      P = P.and(0xfd)
     } else {
-      P = P.or(0x02);
+      P = P.or(0x02)
     }
     if (value.and(0x80) != 0) {
-      P = P.or(0x80);
+      P = P.or(0x80)
     } else {
-      P = P.and(0x7f);
+      P = P.and(0x7f)
     }
   }
 
   fun popWord(): Int {
     return popByte() + popByte().shl(8)
   }
+
+  fun testADC(value: Int) {
+    var tmp: Int
+    if (A.xor(value).and(0x80) != 0) {
+      CLV()
+    } else {
+      setOverflow()
+    }
+
+    if (decimalMode().isSet()) {
+      tmp = A.and(0xf) + value.and(0xf) + carry()
+      if (tmp >= 10) {
+        tmp = 0x10.or((tmp + 6).and(0xf))
+      }
+      tmp += A.and(0xf0) + value.and(0xf0)
+      if (tmp >= 160) {
+        SEC()
+        if (overflow().isSet() && tmp >= 0x180) {
+          CLV()
+        }
+        tmp += 0x60
+      } else {
+        CLC()
+        if (overflow().isSet() && tmp < 0x80) {
+          CLV()
+        }
+      }
+    } else {
+      tmp = A + value + carry()
+      if (tmp >= 0x100) {
+        SEC()
+        if (overflow().isSet() && tmp >= 0x180) {
+          CLV()
+        }
+      } else {
+        CLC()
+        if (overflow().isSet() && tmp < 0x80) {
+          CLV()
+        }
+      }
+    }
+    A = tmp.and(0xff)
+    setSZFlagsForRegA()
+  }
+
+  fun overflow(): Int {
+    return P.and(0x40)
+  }
+
+  fun decimalMode(): Int {
+    return P.and(8);
+  }
+
+  fun carry(): Int {
+    return P.and(1);
+  }
+
+  fun negative(): Int {
+    return P.and(0x80);
+  }
+
+  fun zero(): Int {
+    return P.and(0x02);
+  }
+
+  /** CLear Carry */
+  fun CLC() {
+    P = P.and(0xfe)
+  }
+
+  /** SEt Carry */
+  fun SEC() {
+    P = P.or(1)
+  }
+
+  /** CLear oVerflow */
+  fun CLV() {
+    P = P.and(0xbf)
+  }
+
+  fun setOverflow() {
+    P = P.or(0x40)
+  }
 }

app/src/main/kotlin/android/emu6502/Utils.kt

@@ -2,4 +2,8 @@ package android.emu6502
 
 fun Int.toHexString(): String {
   return java.lang.String.format("%02X", this);
+}
+
+fun Int.isSet(): Boolean {
+  return this != 0
 }

app/src/main/kotlin/android/emu6502/instructions/impl/ADC.kt

@@ -5,6 +5,8 @@ import android.emu6502.instructions.BaseInstruction
 import android.emu6502.instructions.Instruction
 
 /** ADd with Carry */
-class ADC(cpu: CPU)
-    : BaseInstruction(Instruction.ADC, cpu.instructionList) {
+class ADC(private val cpu: CPU) : BaseInstruction(Instruction.ADC, cpu.instructionList) {
+  override fun immediate() {
+    cpu.testADC(cpu.popByte())
+  }
 }

app/src/main/kotlin/android/emu6502/instructions/impl/BRK.kt

@@ -0,0 +1,12 @@
+package android.emu6502.instructions.impl
+
+import android.emu6502.CPU
+import android.emu6502.instructions.BaseInstruction
+import android.emu6502.instructions.Instruction
+
+/** BRreaK */
+final class BRK(private val cpu: CPU) : BaseInstruction(Instruction.INX, cpu.instructionList) {
+  override fun single() {
+    cpu.stop()
+  }
+}

app/src/main/kotlin/android/emu6502/instructions/impl/INX.kt

@@ -0,0 +1,13 @@
+package android.emu6502.instructions.impl
+
+import android.emu6502.CPU
+import android.emu6502.instructions.BaseInstruction
+import android.emu6502.instructions.Instruction
+
+/** INcrement X */
+class INX(private val cpu: CPU) : BaseInstruction(Instruction.INX, cpu.instructionList) {
+  override fun single() {
+    cpu.X = (cpu.X + 1).and(0xff)
+    cpu.setSZflagsForRegX()
+  }
+}

app/src/main/kotlin/android/emu6502/instructions/impl/TAX.kt

@@ -0,0 +1,13 @@
+package android.emu6502.instructions.impl
+
+import android.emu6502.CPU
+import android.emu6502.instructions.BaseInstruction
+import android.emu6502.instructions.Instruction
+
+/** Transfer A to X */
+class TAX(private val cpu: CPU) : BaseInstruction(Instruction.TAX, cpu.instructionList) {
+  override fun single() {
+    cpu.X = cpu.A.and(0xFF)
+    cpu.setSZflagsForRegX()
+  }
+}

app/src/test/java/android/emu6502/CPUTest.java

@@ -0,0 +1,76 @@
+package android.emu6502;
+
+import com.google.common.collect.ImmutableList;
+
+import android.emu6502.instructions.Symbols;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.junit.Assert.assertThat;
+
+public class CPUTest {
+
+  private CPU cpu;
+  private Assembler assembler;
+
+  @Before public void setUp() {
+    Memory memory = new Memory(new Display());
+    assembler = new Assembler(memory, new Symbols());
+    cpu = new CPU(memory);
+  }
+
+  @Test public void testSimple() {
+    List<String> lines = ImmutableList.of(
+        "LDA #$01",
+        "STA $0200",
+        "LDA #$05",
+        "STA $0201",
+        "LDA #$08",
+        "STA $0202");
+    assembler.assembleCode(lines);
+    cpu.execute();
+    assertThat(cpu.getA(), equalTo(0x08));
+    assertThat(cpu.getX(), equalTo(0x00));
+    assertThat(cpu.getY(), equalTo(0x00));
+    assertThat(cpu.getSP(), equalTo(0xFF));
+    assertThat(cpu.getPC(), equalTo(0x0610));
+  }
+
+  @Test public void testWithComments() {
+    List<String> lines = ImmutableList.of(
+        "LDA #$c0  ;Load the hex value $c0 into the A register",
+        "TAX       ;Transfer the value in the A register to X",
+        "INX       ;Increment the value in the X register",
+        "ADC #$c4  ;Add the hex value $c4 to the A register",
+        "BRK       ;Break - we're done");
+    assembler.assembleCode(lines);
+    cpu.execute();
+    assertThat(cpu.getA(), equalTo(0x84));
+    assertThat(cpu.getX(), equalTo(0xC1));
+    assertThat(cpu.getY(), equalTo(0x00));
+    assertThat(cpu.getSP(), equalTo(0xFF));
+    assertThat(cpu.getPC(), equalTo(0x0607));
+  }
+
+  @Test public void testBranchAndLabel() {
+    List<String> lines = ImmutableList.of(
+        "LDX #$08",
+        "decrement:",
+        "DEX",
+        "STX $0200",
+        "CPX #$03",
+        "BNE decrement",
+        "STX $0201",
+        "BRK");
+    assembler.assembleCode(lines);
+    assertThat(cpu.getA(), equalTo(0x00));
+    assertThat(cpu.getX(), equalTo(0x03));
+    assertThat(cpu.getY(), equalTo(0x00));
+    assertThat(cpu.getSP(), equalTo(0xFF));
+    assertThat(cpu.getPC(), equalTo(0x060e));
+  }
+}