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IRQ and NMI handling at CPU level.

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This commit is contained in:
Seth Morabito 2014-01-25 20:45:39 -08:00
parent b6cc480919
commit 76dcbd712a
3 changed files with 428 additions and 251 deletions
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50
src/main/java/com/loomcom/symon/Cpu.java
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@ -160,6 +160,14 @@ public class Cpu implements InstructionTable {
// Store the address from which the IR was read, for debugging
state.lastPc = state.pc;
// Check for Interrupts before doing anything else.
// This will set the PC and jump to the interrupt vector.
if (state.nmiAsserted) {
handleNmi();
} else if (state.irqAsserted && !getIrqDisableFlag()) {
handleIrq();
}
// Fetch memory location for this instruction.
state.ir = bus.read(state.pc);
irAddressMode = (state.ir >> 2) & 0x07;
@ -251,16 +259,7 @@ public class Cpu implements InstructionTable {
/** Single Byte Instructions; Implied and Relative **/
case 0x00: // BRK - Force Interrupt - Implied
if (!getIrqDisableFlag()) {
// Set the break flag before pushing.
setBreakFlag();
// Push program counter + 1 onto the stack
stackPush((state.pc + 1 >> 8) & 0xff); // PC high byte
stackPush(state.pc + 1 & 0xff); // PC low byte
stackPush(state.getStatusFlag());
// Set the Interrupt Disabled flag. RTI will clear it.
setIrqDisableFlag();
// Load interrupt vector address into PC
state.pc = address(bus.read(IRQ_VECTOR_L), bus.read(IRQ_VECTOR_H));
handleIrq();
}
break;
case 0x08: // PHP - Push Processor Status - Implied
@ -733,6 +732,37 @@ public class Cpu implements InstructionTable {
delayLoop(state.ir);
}
private void handleIrq() throws MemoryAccessException {
handleInterrupt(IRQ_VECTOR_L, IRQ_VECTOR_H);
clearIrq();
}
private void handleNmi() throws MemoryAccessException {
handleInterrupt(NMI_VECTOR_L, NMI_VECTOR_H);
clearNmi();
}
/**
* Handle the common behavior of BRK, /IRQ, and /NMI
*
* @throws MemoryAccessException
*/
private void handleInterrupt(int vectorLow, int vectorHigh) throws MemoryAccessException {
// Set the break flag before pushing.
setBreakFlag();
// Push program counter + 1 onto the stack
stackPush((state.pc + 1 >> 8) & 0xff); // PC high byte
stackPush(state.pc + 1 & 0xff); // PC low byte
stackPush(state.getStatusFlag());
// Set the Interrupt Disabled flag. RTI will clear it.
setIrqDisableFlag();
// Load interrupt vector address into PC
state.pc = address(bus.read(vectorLow), bus.read(vectorHigh));
}
/**
* Add with Carry, used by all addressing mode implementations of ADC.
* As a side effect, this will set the overflow and carry flags as

482
src/test/java/com/loomcom/symon/CpuAccumulatorModeTest.java
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@ -7,303 +7,303 @@ import junit.framework.*;
public class CpuAccumulatorModeTest extends TestCase {
protected Cpu cpu;
protected Bus bus;
protected Memory mem;
protected Cpu cpu;
protected Bus bus;
protected Memory mem;
public void setUp() throws MemoryRangeException, MemoryAccessException {
this.cpu = new Cpu();
this.bus = new Bus(0x0000, 0xffff);
this.mem = new Memory(0x0000, 0x10000);
bus.addCpu(cpu);
bus.addDevice(mem);
public void setUp() throws MemoryRangeException, MemoryAccessException {
this.cpu = new Cpu();
this.bus = new Bus(0x0000, 0xffff);
this.mem = new Memory(0x0000, 0x10000);
bus.addCpu(cpu);
bus.addDevice(mem);
// Load the reset vector.
bus.write(0xfffc, Bus.DEFAULT_LOAD_ADDRESS & 0x00ff);
bus.write(0xfffd, (Bus.DEFAULT_LOAD_ADDRESS & 0xff00)>>>8);
// Load the reset vector.
bus.write(0xfffc, Bus.DEFAULT_LOAD_ADDRESS & 0x00ff);
bus.write(0xfffd, (Bus.DEFAULT_LOAD_ADDRESS & 0xff00) >>> 8);
cpu.reset();
cpu.reset();
// Assert initial state
assertEquals(0, cpu.getAccumulator());
assertEquals(0, cpu.getXRegister());
assertEquals(0, cpu.getYRegister());
assertEquals(0x200, cpu.getProgramCounter());
assertEquals(0xff, cpu.getStackPointer());
assertEquals(0x20, cpu.getProcessorStatus());
}
// Assert initial state
assertEquals(0, cpu.getAccumulator());
assertEquals(0, cpu.getXRegister());
assertEquals(0, cpu.getYRegister());
assertEquals(0x200, cpu.getProgramCounter());
assertEquals(0xff, cpu.getStackPointer());
assertEquals(0x20, cpu.getProcessorStatus());
}
/*
* The following opcodes are tested for correctness in this file:
*
* ASL - $0a
* ROL - $2a
* LSR - $4a
* ROR - $6a
*/
/*
* The following opcodes are tested for correctness in this file:
*
* ASL - $0a
* ROL - $2a
* LSR - $4a
* ROR - $6a
*/
/* ASL - Arithmetic Shift Left - $0a */
public void test_ASL() throws MemoryAccessException {
bus.loadProgram(0xa9, 0x00, // LDA #$00
0x0a, // ASL A
public void test_ASL() throws MemoryAccessException {
bus.loadProgram(0xa9, 0x00, // LDA #$00
0x0a, // ASL A
0xa9, 0x01, // LDA #$01
0x0a, // ASL A
0xa9, 0x01, // LDA #$01
0x0a, // ASL A
0xa9, 0x02, // LDA #$02
0x0a, // ASL A
0xa9, 0x02, // LDA #$02
0x0a, // ASL A
0xa9, 0x44, // LDA #$44
0x0a, // ASL A
0xa9, 0x44, // LDA #$44
0x0a, // ASL A
0xa9, 0x80, // LDA #$80
0x0a); // ASL A
0xa9, 0x80, // LDA #$80
0x0a); // ASL A
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x02, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x02, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x04, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x04, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x88, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertTrue(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x88, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertTrue(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertTrue(cpu.getCarryFlag());
}
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertTrue(cpu.getCarryFlag());
}
/* ROL - Rotate Left - $2a */
public void test_ROL() throws MemoryAccessException {
bus.loadProgram(0xa9, 0x00, // LDA #$00
0x2a, // ROL A (m=%00000000, c=0)
0xa9, 0x01, // LDA #$01
0x2a, // ROL A (m=%00000010, c=0)
0x38, // SEC (m=%00000010, c=1)
0x2a, // ROL A (m=%00000101, c=0)
0x2a, // ROL A (m=%00001010, c=0)
0x2a, // ROL A (m=%00010100, c=0)
0x2a, // ROL A (m=%00101000, c=0)
0x2a, // ROL A (m=%01010000, c=0)
0x2a, // ROL A (m=%10100000, c=0)
0x2a, // ROL A (m=%01000000, c=1)
0x2a); // ROL A (m=%10000001, c=0)
public void test_ROL() throws MemoryAccessException {
bus.loadProgram(0xa9, 0x00, // LDA #$00
0x2a, // ROL A (m=%00000000, c=0)
0xa9, 0x01, // LDA #$01
0x2a, // ROL A (m=%00000010, c=0)
0x38, // SEC (m=%00000010, c=1)
0x2a, // ROL A (m=%00000101, c=0)
0x2a, // ROL A (m=%00001010, c=0)
0x2a, // ROL A (m=%00010100, c=0)
0x2a, // ROL A (m=%00101000, c=0)
0x2a, // ROL A (m=%01010000, c=0)
0x2a, // ROL A (m=%10100000, c=0)
0x2a, // ROL A (m=%01000000, c=1)
0x2a); // ROL A (m=%10000001, c=0)
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x02, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x02, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x05, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x05, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x0a, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x0a, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x14, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x14, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x28, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x28, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x50, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x50, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0xa0, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertTrue(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0xa0, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertTrue(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x40, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertTrue(cpu.getCarryFlag());
cpu.step();
assertEquals(0x40, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertTrue(cpu.getCarryFlag());
cpu.step();
assertEquals(0x81, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertTrue(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
}
cpu.step();
assertEquals(0x81, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertTrue(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
}
/* LSR - Logical Shift Right - $4a */
public void test_LSR() throws MemoryAccessException {
bus.loadProgram(0xa9, 0x00, // LDA #$00
0x4a, // LSR A
public void test_LSR() throws MemoryAccessException {
bus.loadProgram(0xa9, 0x00, // LDA #$00
0x4a, // LSR A
0xa9, 0x01, // LDA #$01
0x4a, // LSR A
0xa9, 0x01, // LDA #$01
0x4a, // LSR A
0xa9, 0x02, // LDA #$02
0x4a, // LSR A
0xa9, 0x02, // LDA #$02
0x4a, // LSR A
0xa9, 0x44, // LDA #$44
0x4a, // LSR A
0xa9, 0x44, // LDA #$44
0x4a, // LSR A
0xa9, 0x80, // LDA #$80
0x4a, // LSR A
0xa9, 0x80, // LDA #$80
0x4a, // LSR A
0x38, // SEC
0xa9, 0x02, // LDA #$02
0x4a); // LSR $05
0x38, // SEC
0xa9, 0x02, // LDA #$02
0x4a); // LSR $05
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertTrue(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertTrue(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x01, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x01, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x22, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x22, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x40, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x40, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
// Setting Carry should not affect the result.
cpu.step(3);
assertEquals(0x01, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
}
// Setting Carry should not affect the result.
cpu.step(3);
assertEquals(0x01, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
}
/* ROR - Rotate Right - $6a */
public void test_ROR() throws MemoryAccessException {
bus.loadProgram(0xa9, 0x00, // LDA #$00
0x6a, // ROR A (m=%00000000, c=0)
0xa9, 0x10, // LDA #$10
0x6a, // ROR A (m=%00001000, c=0)
0x6a, // ROR A (m=%00000100, c=0)
0x6a, // ROR A (m=%00000010, c=0)
0x6a, // ROR A (m=%00000001, c=0)
0x6a, // ROR A (m=%00000000, c=1)
0x6a, // ROR A (m=%10000000, c=0)
0x6a, // ROR A (m=%01000000, c=0)
0x6a, // ROR A (m=%00100000, c=0)
0x6a); // ROR A (m=%00010000, c=0)
public void test_ROR() throws MemoryAccessException {
bus.loadProgram(0xa9, 0x00, // LDA #$00
0x6a, // ROR A (m=%00000000, c=0)
0xa9, 0x10, // LDA #$10
0x6a, // ROR A (m=%00001000, c=0)
0x6a, // ROR A (m=%00000100, c=0)
0x6a, // ROR A (m=%00000010, c=0)
0x6a, // ROR A (m=%00000001, c=0)
0x6a, // ROR A (m=%00000000, c=1)
0x6a, // ROR A (m=%10000000, c=0)
0x6a, // ROR A (m=%01000000, c=0)
0x6a, // ROR A (m=%00100000, c=0)
0x6a); // ROR A (m=%00010000, c=0)
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x08, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step(2);
assertEquals(0x08, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x04, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x04, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x02, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x02, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x01, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x01, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertTrue(cpu.getCarryFlag());
cpu.step();
assertEquals(0x00, cpu.getAccumulator());
assertTrue(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertTrue(cpu.getCarryFlag());
cpu.step();
assertEquals(0x80, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertTrue(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x80, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertTrue(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x40, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x40, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x20, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x20, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
cpu.step();
assertEquals(0x10, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
}
cpu.step();
assertEquals(0x10, cpu.getAccumulator());
assertFalse(cpu.getZeroFlag());
assertFalse(cpu.getNegativeFlag());
assertFalse(cpu.getCarryFlag());
}
}

147
src/test/java/com/loomcom/symon/CpuTest.java
View File

@ -345,6 +345,153 @@ public class CpuTest extends TestCase {
assertFalse(cpu.getNegativeFlag());
}
public void testIrq() throws Exception {
// Ensure the IRQ disable flag is cleared
cpu.clearIrqDisableFlag();
// Set the IRQ vector
bus.write(0xffff, 0x12);
bus.write(0xfffe, 0x34);
// Create an IRQ handler at 0x1234
cpu.setProgramCounter(0x1234);
bus.loadProgram(0xa9, 0x33, // LDA #$33
0x69, 0x01); // ADC #$01
cpu.setProgramCounter(0x0200);
// Create a little program at 0x0200
bus.loadProgram(0x18, // CLC
0xa9, 0x01, // LDA #$00
0x69, 0x01); // ADC #$01
cpu.step();
assertEquals(0x0201, cpu.getProgramCounter()); // First instruction executed.
assertEquals(0x00, cpu.getAccumulator());
cpu.step();
assertEquals(0x0203, cpu.getProgramCounter());
assertEquals(0x01, cpu.getAccumulator());
cpu.assertIrq();
cpu.step();
assertTrue(cpu.getIrqDisableFlag()); // Should have been set by the IRQ
assertEquals(0x1236, cpu.getProgramCounter());
assertEquals(0x33, cpu.getAccumulator());
// Be sure that the IRQ line is no longer held low
assertFalse(cpu.getCpuState().irqAsserted);
}
public void testIrqHonorsIrqDisabledFlag() throws Exception {
// Ensure the IRQ disable flag is set
cpu.setIrqDisableFlag();
// Set the IRQ vector
bus.write(0xffff, 0x12);
bus.write(0xfffe, 0x34);
// Create an IRQ handler at 0x1234
cpu.setProgramCounter(0x1234);
bus.loadProgram(0xa9, 0x33, // LDA #$33
0x69, 0x01); // ADC #$01
cpu.setProgramCounter(0x0200);
// Create a little program at 0x0200
bus.loadProgram(0x18, // CLC
0xa9, 0x01, // LDA #$00
0x69, 0x01); // ADC #$01
cpu.step();
assertEquals(0x0201, cpu.getProgramCounter()); // First instruction executed.
assertEquals(0x00, cpu.getAccumulator());
cpu.step();
assertEquals(0x0203, cpu.getProgramCounter());
assertEquals(0x01, cpu.getAccumulator());
cpu.assertIrq(); // Should be ignored, because the disable flag is set.
cpu.step();
assertTrue(cpu.getIrqDisableFlag()); // Should have been left alone.
assertEquals(0x0205, cpu.getProgramCounter());
assertEquals(0x02, cpu.getAccumulator());
}
public void testNmi() throws Exception {
// Set the NMI vector to 0x1000
bus.write(0xfffb, 0x10);
bus.write(0xfffa, 0x00);
// Create an NMI handler at 0x1000
cpu.setProgramCounter(0x1000);
bus.loadProgram(0xa9, 0x33, // LDA #$33
0x69, 0x01); // ADC #$01
// Create a little program at 0x0200
cpu.setProgramCounter(0x0200);
bus.loadProgram(0x18, // CLC
0xa9, 0x01, // LDA #$00
0x69, 0x01); // ADC #$01
cpu.step();
assertEquals(0x0201, cpu.getProgramCounter()); // First instruction executed.
assertEquals(0x00, cpu.getAccumulator());
cpu.step();
assertEquals(0x0203, cpu.getProgramCounter());
assertEquals(0x01, cpu.getAccumulator());
cpu.assertNmi();
cpu.step();
assertTrue(cpu.getIrqDisableFlag()); // Should have been set by the NMI
assertEquals(0x1002, cpu.getProgramCounter());
assertEquals(0x33, cpu.getAccumulator());
// Be sure that the NMI line is no longer held low
assertFalse(cpu.getCpuState().nmiAsserted);
}
public void testNmiIgnoresIrqDisableFlag() throws Exception {
// Set the IRQ disable flag, which should be ignored by the NMI
cpu.setIrqDisableFlag();
// Set the NMI vector to 0x1000
bus.write(0xfffb, 0x10);
bus.write(0xfffa, 0x00);
// Create an NMI handler at 0x1000
cpu.setProgramCounter(0x1000);
bus.loadProgram(0xa9, 0x33, // LDA #$33
0x69, 0x01); // ADC #$01
// Create a little program at 0x0200
cpu.setProgramCounter(0x0200);
bus.loadProgram(0x18, // CLC
0xa9, 0x01, // LDA #$00
0x69, 0x01); // ADC #$01
cpu.step();
assertEquals(0x0201, cpu.getProgramCounter()); // First instruction executed.
assertEquals(0x00, cpu.getAccumulator());
cpu.step();
assertEquals(0x0203, cpu.getProgramCounter());
assertEquals(0x01, cpu.getAccumulator());
cpu.assertNmi();
cpu.step();
assertTrue(cpu.getIrqDisableFlag()); // Should have been set by the NMI
assertEquals(0x1002, cpu.getProgramCounter());
assertEquals(0x33, cpu.getAccumulator());
// Be sure that the NMI line is no longer held low
assertFalse(cpu.getCpuState().nmiAsserted);
}
public void testAddress() {
assertEquals(0xf1ea, cpu.address(0xea, 0xf1));
assertEquals(0x00ea, cpu.address(0xea, 0x00));