Fixed the BRK instruction. Added SBC and ADC in Binary Coded Decimal

mode.  More unit tests.

src/test/java/com/loomcom/symon/CpuImmediateModeTest.java

@@ -252,6 +252,83 @@ public class CpuImmediateModeTest extends TestCase {
 		assertFalse(cpu.getCarryFlag());
 	}
 
+	public void test_ADC_DecimalMode() {
+		bus.loadProgram(0xf8,        // SED
+		                0xa9, 0x01,  // LDA #$01
+		                0x69, 0x01); // ADC #$01
+		cpu.step(3);
+		assertEquals(0x02, cpu.getAccumulator());
+		assertFalse(cpu.getNegativeFlag());
+		assertFalse(cpu.getOverflowFlag());
+		assertFalse(cpu.getZeroFlag());
+		assertFalse(cpu.getCarryFlag());
+
+		cpu.reset();
+		bus.loadProgram(0xf8,        // SED
+		                0xa9, 0x49,  // LDA #$49
+		                0x69, 0x01); // ADC #$01
+		cpu.step(3);
+		assertEquals(0x50, cpu.getAccumulator());
+		assertFalse(cpu.getNegativeFlag());
+		assertFalse(cpu.getOverflowFlag());
+		assertFalse(cpu.getZeroFlag());
+		assertFalse(cpu.getCarryFlag());
+
+		cpu.reset();
+		bus.loadProgram(0xf8,        // SED
+		                0xa9, 0x50,  // LDA #$50
+		                0x69, 0x01); // ADC #$01
+		cpu.step(3);
+		assertEquals(0x51, cpu.getAccumulator());
+		assertFalse(cpu.getNegativeFlag());
+		assertFalse(cpu.getOverflowFlag());
+		assertFalse(cpu.getZeroFlag());
+		assertFalse(cpu.getCarryFlag());
+
+		cpu.reset();
+		bus.loadProgram(0xf8,        // SED
+		                0xa9, 0x99,  // LDA #$99
+		                0x69, 0x01); // ADC #$01
+		cpu.step(3);
+		assertEquals(0x00, cpu.getAccumulator());
+		assertFalse(cpu.getNegativeFlag());
+		assertFalse(cpu.getOverflowFlag());
+		assertTrue(cpu.getZeroFlag());
+		assertTrue(cpu.getCarryFlag());
+
+		cpu.reset();
+		bus.loadProgram(0xf8,        // SED
+		                0xa9, 0x00,  // LDA #$00
+		                0x69, 0x99); // ADC #$01
+		cpu.step(3);
+		assertEquals(0x99, cpu.getAccumulator());
+		assertFalse(cpu.getNegativeFlag());
+		assertFalse(cpu.getOverflowFlag());
+		assertFalse(cpu.getZeroFlag());
+		assertFalse(cpu.getCarryFlag());
+
+		cpu.reset();
+		bus.loadProgram(0xf8,        // SED
+		                0xa9, 0x49,  // LDA #$49
+		                0x69, 0x99); // ADC #$99
+		cpu.step(3);
+		assertEquals(0x48, cpu.getAccumulator());
+		assertFalse(cpu.getNegativeFlag());
+		assertFalse(cpu.getOverflowFlag());
+		assertFalse(cpu.getZeroFlag());
+		assertTrue(cpu.getCarryFlag());
+
+		cpu.reset();
+		bus.loadProgram(0xf8,        // SED
+		                0xa9, 0x50,  // LDA #$59
+		                0x69, 0x99); // ADC #$99
+		cpu.step(3);
+		assertEquals(0x49, cpu.getAccumulator());
+		assertFalse(cpu.getNegativeFlag());
+		assertFalse(cpu.getOverflowFlag());
+		assertFalse(cpu.getZeroFlag());
+		assertTrue(cpu.getCarryFlag());
+	}
 
 	/* LDY Immediate Mode Tests - 0xa0 */
 
@@ -616,11 +693,43 @@ public class CpuImmediateModeTest extends TestCase {
 	}
 
 	public void test_SBC_IncludesNotOfCarry() {
+		// Subtrace with Carry Flag cleared
+		bus.loadProgram(0x18,        // CLC
+		                0xa9, 0x05,  // LDA #$00
+		                0xe9, 0x01); // SBC #$01
+		
+		cpu.step(3);
+		assertEquals(0x03, cpu.getAccumulator());
+		
 		cpu.reset();
+
+		// Subtrace with Carry Flag cleared
+		bus.loadProgram(0x18,        // CLC
+		                0xa9, 0x00,  // LDA #$00
+		                0xe9, 0x01); // SBC #$01
+		
+		cpu.step(3);
+		assertEquals(0xfe, cpu.getAccumulator());
+	
+		cpu.reset();
+		
+		// Subtract with Carry Flag set
+		bus.loadProgram(0x38,        // SEC
+										0xa9, 0x05,  // LDA #$00
+										0xe9, 0x01); // SBC #$01
+		cpu.step(3);
+		assertEquals(0x04, cpu.getAccumulator());
+		assertTrue(cpu.getCarryFlag());
+		
+		cpu.reset();
+		
+		// Subtract with Carry Flag set
 		bus.loadProgram(0x38,        // SEC
 										0xa9, 0x00,  // LDA #$00
 										0xe9, 0x01); // SBC #$01
 		cpu.step(3);
 		assertEquals(0xff, cpu.getAccumulator());
+		assertFalse(cpu.getCarryFlag());
+
 	}
 }

src/test/java/com/loomcom/symon/CpuImpliedModeTest.java

@@ -78,10 +78,16 @@ public class CpuImpliedModeTest extends TestCase {
 		assertEquals(0x0200, cpu.getProgramCounter());
 		assertEquals(0xff, cpu.getStackPointer());
 
+		// Set the IRQ vector
+		bus.write(Cpu.IRQ_VECTOR_H, 0x12);
+		bus.write(Cpu.IRQ_VECTOR_L, 0x34);
+
 		bus.loadProgram(0xea,
 										0xea,
 										0xea,
-										0x00);
+										0x00,
+										0xea,
+										0xea);
 
 		cpu.step(3); // Three NOP instructions
 
@@ -89,19 +95,20 @@ public class CpuImpliedModeTest extends TestCase {
 
 		cpu.step(); // Triggers the BRK
 
-		// Was at PC = 0x204, which should now be on the stack
+		// Was at PC = 0x204.  PC+2 should now be on the stack
 		assertEquals(0x02, bus.read(0x1ff)); // PC high byte
-		assertEquals(0x04, bus.read(0x1fe)); // PC low byte
-		assertEquals(0x20|Cpu.P_CARRY|Cpu.P_OVERFLOW,
-								 bus.read(0x1fd));       // Processor Status
-
-		// Reset to original contents of PC
-		assertEquals(0x0200, cpu.getProgramCounter());
-		assertEquals(0xfc, cpu.getStackPointer());
+		assertEquals(0x06, bus.read(0x1fe)); // PC low byte
 		assertEquals(0x20|Cpu.P_CARRY|Cpu.P_OVERFLOW|Cpu.P_BREAK,
+								 bus.read(0x1fd));       // Processor Status, with B set
+
+		// Interrupt vector held 0x1234, so we should be there.
+		assertEquals(0x1234, cpu.getProgramCounter());
+		assertEquals(0xfc, cpu.getStackPointer());
+
+		// B and I flags should have been set on P
+		assertEquals(0x20|Cpu.P_CARRY|Cpu.P_OVERFLOW|Cpu.P_BREAK|
+		             Cpu.P_IRQ_DISABLE,
 								 cpu.getProcessorStatus());
-		assertEquals(0x20|Cpu.P_CARRY|Cpu.P_OVERFLOW,
-								 cpu.stackPeek());
 	}
 
 	public void test_BRK_HonorsIrqDisableFlag() {