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b5a470d3ba
When describing the CPU's reset pin, the W65C02S data sheet says: > All Registers are initialized by software except the Decimal and Interrupt > disable mode select bits of the Processor Status Register (P) are initialized > by hardware. It then has a diagram of the power-on state of the processor status register: > 7 6 5 4 3 2 1 0 > * * 1 1 0 1 * * > N V - B D I Z C > > * = software initialized Confusingly the text indicates that only the D and I flags are initialised by hardware, while the diagram indicates that the B flag is initialised too. Meanwhile, https://www.nesdev.org/wiki/CPU_power_up_state says that the power-on state of the NES CPU is $34 (exactly matching the diagram above) but https://www.nesdev.org/wiki/Status_flags#The_B_flag says that the B flag does not physically exist within P register, it's only relevant in the copy of P that gets pushed to the stack by BRK (set), PHP (set), or an interrupt signal (cleared). As a result, the most sensible power-on state for the processor status register is with the "interrupt disable" flag set and everything else cleared.
282 lines
8.8 KiB
Java
282 lines
8.8 KiB
Java
package com.loomcom.symon;
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import com.loomcom.symon.devices.Memory;
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import com.loomcom.symon.exceptions.MemoryAccessException;
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import junit.framework.TestCase;
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public class CpuRelativeModeTest extends TestCase {
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protected Cpu cpu;
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protected Bus bus;
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protected Memory mem;
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protected void setUp() throws Exception {
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this.cpu = new Cpu();
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this.bus = new Bus(0x0000, 0xffff);
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this.mem = new Memory(0x0000, 0xffff);
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bus.addCpu(cpu);
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bus.addDevice(mem);
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// Load the reset vector.
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bus.write(0xfffc, Bus.DEFAULT_LOAD_ADDRESS & 0x00ff);
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bus.write(0xfffd, (Bus.DEFAULT_LOAD_ADDRESS & 0xff00) >>> 8);
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cpu.reset();
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// Assert initial state
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assertEquals(0, cpu.getAccumulator());
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assertEquals(0, cpu.getXRegister());
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assertEquals(0, cpu.getYRegister());
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assertEquals(0x200, cpu.getProgramCounter());
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assertEquals(0xff, cpu.getStackPointer());
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assertEquals(0x24, cpu.getProcessorStatus());
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}
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/*
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* The following opcodes are tested for correctness in this file:
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*
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* BPL - Branch if Positive - 0x10
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* BMI - Branch if Minus - 0x30
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* BVC - Branch if Overflow Clear - 0x50
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* BVS - Branch if Overflow Set - 0x70
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* BCC - Branch if Carry Clear - 0x90
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* BCS - Branch if Carry Set - 0xb0
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* BNE - Branch if Not Equal to Zero - 0xd0
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* BEQ - Branch if Equal to Zero - 0xf0
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*
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*/
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/* BPL - Branch if Positive - 0x10 */
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public void test_BPL() throws MemoryAccessException {
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// Positive Offset
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bus.loadProgram(0x10, 0x05); // BPL $05 ; *=$0202+$05 ($0207)
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cpu.setNegativeFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0x10, 0x05); // BPL $05 ; *=$0202+$05 ($0207)
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cpu.clearNegativeFlag();
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cpu.step();
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assertEquals(0x207, cpu.getProgramCounter());
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// Negative Offset
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cpu.reset();
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bus.loadProgram(0x10, 0xfb); // BPL $fb ; *=$0202-$05 ($01fd)
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cpu.setNegativeFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0x10, 0xfb); // BPL $fb ; *=$0202-$05 ($01fd)
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cpu.clearNegativeFlag();
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cpu.step();
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assertEquals(0x1fd, cpu.getProgramCounter());
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}
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/* BMI - Branch if Minus - 0x30 */
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public void test_BMI() throws MemoryAccessException {
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// Positive Offset
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bus.loadProgram(0x30, 0x05); // BMI $05 ; *=$0202+$05 ($0207)
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cpu.setNegativeFlag();
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cpu.step();
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assertEquals(0x207, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0x30, 0x05); // BMI $05 ; *=$0202+$05 ($0207)
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cpu.clearNegativeFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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// Negative Offset
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cpu.reset();
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bus.loadProgram(0x30, 0xfb); // BMI $fb ; *=$0202-$05 ($01fd)
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cpu.setNegativeFlag();
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cpu.step();
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assertEquals(0x1fd, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0x30, 0xfb); // BMI $fb ; *=$0202-$05 ($01fd)
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cpu.clearNegativeFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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}
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/* BVC - Branch if Overflow Clear - 0x50 */
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public void test_BVC() throws MemoryAccessException {
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// Positive Offset
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bus.loadProgram(0x50, 0x05); // BVC $05 ; *=$0202+$05 ($0207)
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cpu.setOverflowFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0x50, 0x05); // BVC $05 ; *=$0202+$05 ($0207)
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cpu.clearOverflowFlag();
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cpu.step();
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assertEquals(0x207, cpu.getProgramCounter());
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// Negative Offset
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cpu.reset();
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bus.loadProgram(0x50, 0xfb); // BVC $fb ; *=$0202-$05 ($01fd)
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cpu.setOverflowFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0x50, 0xfb); // BVC $fb ; *=$0202-$05 ($01fd)
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cpu.clearOverflowFlag();
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cpu.step();
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assertEquals(0x1fd, cpu.getProgramCounter());
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}
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/* BVS - Branch if Overflow Set - 0x70 */
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public void test_BVS() throws MemoryAccessException {
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// Positive Offset
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bus.loadProgram(0x70, 0x05); // BVS $05 ; *=$0202+$05 ($0207)
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cpu.setOverflowFlag();
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cpu.step();
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assertEquals(0x207, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0x70, 0x05); // BVS $05 ; *=$0202+$05 ($0207)
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cpu.clearOverflowFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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// Negative Offset
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cpu.reset();
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bus.loadProgram(0x70, 0xfb); // BVS $fb ; *=$0202-$05 ($01fd)
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cpu.setOverflowFlag();
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cpu.step();
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assertEquals(0x1fd, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0x70, 0xfb); // BVS $fb ; *=$0202-$05 ($01fd)
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cpu.clearOverflowFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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}
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/* BCC - Branch if Carry Clear - 0x90 */
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public void test_BCC() throws MemoryAccessException {
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// Positive Offset
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bus.loadProgram(0x90, 0x05); // BCC $05 ; *=$0202+$05 ($0207)
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cpu.setCarryFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0x90, 0x05); // BCC $05 ; *=$0202+$05 ($0207)
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cpu.clearCarryFlag();
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cpu.step();
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assertEquals(0x207, cpu.getProgramCounter());
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// Negative Offset
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cpu.reset();
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bus.loadProgram(0x90, 0xfb); // BCC $fb ; *=$0202-$05 ($01fd)
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cpu.setCarryFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0x90, 0xfb); // BCC $fb ; *=$0202-$05 ($01fd)
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cpu.clearCarryFlag();
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cpu.step();
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assertEquals(0x1fd, cpu.getProgramCounter());
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}
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/* BCS - Branch if Carry Set - 0xb0 */
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public void test_BCS() throws MemoryAccessException {
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// Positive Offset
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bus.loadProgram(0xb0, 0x05); // BCS $05 ; *=$0202+$05 ($0207)
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cpu.setCarryFlag();
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cpu.step();
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assertEquals(0x207, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0xb0, 0x05); // BCS $05 ; *=$0202+$05 ($0207)
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cpu.clearCarryFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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// Negative Offset
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cpu.reset();
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bus.loadProgram(0xb0, 0xfb); // BCS $fb ; *=$0202-$05 ($01fd)
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cpu.setCarryFlag();
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cpu.step();
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assertEquals(0x1fd, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0xb0, 0xfb); // BCS $fb ; *=$0202-$05 ($01fd)
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cpu.clearCarryFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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}
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/* BNE - Branch if Not Equal to Zero - 0xd0 */
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public void test_BNE() throws MemoryAccessException {
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// Positive Offset
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bus.loadProgram(0xd0, 0x05); // BNE $05 ; *=$0202+$05 ($0207)
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cpu.setZeroFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0xd0, 0x05); // BNE $05 ; *=$0202+$05 ($0207)
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cpu.clearZeroFlag();
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cpu.step();
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assertEquals(0x207, cpu.getProgramCounter());
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// Negative Offset
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cpu.reset();
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bus.loadProgram(0xd0, 0xfb); // BNE $fb ; *=$0202-$05 ($01fd)
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cpu.setZeroFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0xd0, 0xfb); // BNE $fb ; *=$0202-$05 ($01fd)
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cpu.clearZeroFlag();
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cpu.step();
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assertEquals(0x1fd, cpu.getProgramCounter());
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}
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/* BEQ - Branch if Equal to Zero - 0xf0 */
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public void test_BEQ() throws MemoryAccessException {
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// Positive Offset
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bus.loadProgram(0xf0, 0x05); // BEQ $05 ; *=$0202+$05 ($0207)
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cpu.setZeroFlag();
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cpu.step();
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assertEquals(0x207, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0xf0, 0x05); // BEQ $05 ; *=$0202+$05 ($0207)
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cpu.clearZeroFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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// Negative Offset
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cpu.reset();
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bus.loadProgram(0xf0, 0xfb); // BEQ $fb ; *=$0202-$05 ($01fd)
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cpu.setZeroFlag();
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cpu.step();
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assertEquals(0x1fd, cpu.getProgramCounter());
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cpu.reset();
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bus.loadProgram(0xf0, 0xfb); // BEQ $fb ; *=$0202-$05 ($01fd)
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cpu.clearZeroFlag();
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cpu.step();
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assertEquals(0x202, cpu.getProgramCounter());
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}
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}
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