package com.loomcom.symon;

import com.loomcom.symon.devices.Memory;

import org.junit.*;

import static org.junit.Assert.*;

public class CpuIndexedIndirectModeTest {

    protected Cpu    cpu;
    protected Bus    bus;
    protected Memory mem;

    @Before
    public void runBeforeEveryTest() throws Exception {
        this.cpu = new Cpu();
        this.bus = new Bus(0x0000, 0xffff);
        this.mem = new Memory(0x0000, 0xffff);
        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);

        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());
    }

    @Test
    public void test_LDA() throws Exception {
        bus.write(0x008c, 0x3f);
        bus.write(0x008d, 0xc4);
        bus.write(0xc43f, 0x45);

        cpu.setXRegister(0x0c);

        bus.loadProgram(0xa1, 0x80); // LDA ($80,X)
        cpu.step(1);

        assertEquals(0x45, cpu.getAccumulator());
    }

    @Test
    public void testZeroPageWrap() throws Exception {
        bus.write(0x0020, 0x01);
        bus.write(0x0021, 0x07); // ($0701)
        bus.write(0x0701, 0xaa);

        bus.write(0x000f, 0x02);
        bus.write(0x0010, 0x08); // ($0802)
        bus.write(0x0802, 0xbb);

        bus.write(0x010f, 0x03);
        bus.write(0x0110, 0x09); // ($0903)
        bus.write(0x0903, 0xcc);

        cpu.setXRegister(0x10);

        // No wrap needed
        bus.loadProgram(0xa1, 0x10,  // LDA ($10,X) = ($10 + $10) & $ff =  $20
                        0xa1, 0xff); // LDA ($ff,X) = ($ff + $10) & $ff =  $0f, NOT $10f!
        cpu.step(1);
        assertEquals(0xaa, cpu.getAccumulator());

        cpu.step(1);
        assertEquals(0xbb, cpu.getAccumulator());
    }

    @Test
    public void test_ORA() throws Exception {
        bus.write(0x0012, 0x1f);
        bus.write(0x0013, 0xc5);
        bus.write(0xc51f, 0x31);

        cpu.setXRegister(0x02);
        cpu.setAccumulator(0x15);

        bus.loadProgram(0x01, 0x10); // ORA ($10,X)
        cpu.step(1);

        assertEquals(0x35, cpu.getAccumulator());
        assertEquals(0x31, bus.read(0xc51f));
    }

    @Test
    public void test_AND() throws Exception {
        bus.write(0x0012, 0x1f);
        bus.write(0x0013, 0xc5);
        bus.write(0xc51f, 0x31);

        cpu.setXRegister(0x02);
        cpu.setAccumulator(0x15);

        bus.loadProgram(0x21, 0x10); // AND ($10,X)
        cpu.step(1);

        assertEquals(0x11, cpu.getAccumulator());
        assertEquals(0x31, bus.read(0xc51f));
    }
}