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Code Issues Projects Releases Wiki Activity

Adds jump instructions

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This commit is contained in:
Felipe Lima 2015-06-21 18:06:44 -07:00
parent 4f9f9c4b9b
commit df2e9fac8f
6 changed files with 139 additions and 6 deletions
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26
app/src/main/kotlin/android/emu6502/CPU.kt
View File

@ -41,7 +41,10 @@ class CPU(val memory: Memory) {
Pair(Instruction.ORA, ORA(this)),
Pair(Instruction.CPX, CPX(this)),
Pair(Instruction.BRK, BRK(this)),
Pair(Instruction.BNE, BNE(this))
Pair(Instruction.BNE, BNE(this)),
Pair(Instruction.JMP, JMP(this)),
Pair(Instruction.JSR, JSR(this)),
Pair(Instruction.RTS, RTS(this))
// Pair(Instruction.BPL, BPL(this)),
// Pair(Instruction.BMI, BMI(this)),
// Pair(Instruction.BVC, BVC(this)),
@ -61,8 +64,6 @@ class CPU(val memory: Memory) {
// Pair(Instruction.CLD, CLD(this)),
// Pair(Instruction.SED, SED(this)),
// Pair(Instruction.INC, INC(this)),
// Pair(Instruction.JMP, JMP(this)),
// Pair(Instruction.JSR, JSR(this)),
// Pair(Instruction.LSR, LSR(this)),
// Pair(Instruction.NOP, NOP(this)),
// Pair(Instruction.TXA, TXA(this)),
@ -73,7 +74,6 @@ class CPU(val memory: Memory) {
// Pair(Instruction.ROR, ROR(this)),
// Pair(Instruction.ROL, ROL(this)),
// Pair(Instruction.RTI, RTI(this)),
// Pair(Instruction.RTS, RTS(this)),
// Pair(Instruction.SBC, SBC(this)),
// Pair(Instruction.TXS, TXS(this)),
// Pair(Instruction.TSX, TSX(this)),
@ -248,6 +248,24 @@ class CPU(val memory: Memory) {
P = P.or(0x40)
}
fun stackPush(value: Int) {
memory.set(SP.and(0xff) + 0x100, value.and(0xff))
SP--
if (SP < 0) {
SP = SP.and(0xff)
Log.i(TAG, "6502 Stack filled! Wrapping...")
}
}
fun stackPop(): Int {
SP++;
if (SP >= 0x100) {
SP = SP.and(0xff)
Log.i(TAG, "6502 Stack emptied! Wrapping...")
}
return memory.get(SP + 0x100)
}
/**
* http://nesdev.com/6502.txt
* Returns the processor flags in the format SV-BDIZC

24
app/src/main/kotlin/android/emu6502/instructions/BaseInstruction.kt
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@ -18,38 +18,62 @@ open class BaseInstruction(private val instruction: Instruction,
}
open fun immediate() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with immediate addressing")
}
open fun zeroPage() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with zeroPage addressing")
}
open fun zeroPageX() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with zeroPageX addressing")
}
open fun zeroPageY() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with zeroPageY addressing")
}
open fun absolute() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with absolute addressing")
}
open fun absoluteX() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with absoluteX addressing")
}
open fun absoluteY() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with absoluteY addressing")
}
open fun indirect() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with indirect addressing")
}
open fun indirectX() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with indirectX addressing")
}
open fun indirectY() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with indirectY addressing")
}
open fun single() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with single addressing")
}
open fun branch() {
throw IllegalStateException("Instruction " + javaClass.getSimpleName() + " not implemented" +
" with branch addressing")
}
}

12
app/src/main/kotlin/android/emu6502/instructions/impl/JMP.kt Normal file
View File

@ -0,0 +1,12 @@
package android.emu6502.instructions.impl
import android.emu6502.CPU
import android.emu6502.instructions.BaseInstruction
import android.emu6502.instructions.Instruction
/** JuMP */
class JMP(private val cpu: CPU) : BaseInstruction(Instruction.JMP, cpu.instructionList) {
override fun absolute() {
cpu.PC = cpu.popWord()
}
}

17
app/src/main/kotlin/android/emu6502/instructions/impl/JSR.kt Normal file
View File

@ -0,0 +1,17 @@
package android.emu6502.instructions.impl
import android.emu6502.CPU
import android.emu6502.instructions.BaseInstruction
import android.emu6502.instructions.Instruction
/** Jump to SubRoutine */
class JSR(private val cpu: CPU) : BaseInstruction(Instruction.JSR, cpu.instructionList) {
override fun absolute() {
val addr = cpu.popWord()
val currAddr = cpu.PC - 1
cpu.stackPush(currAddr.shr(8).and(0xff))
cpu.stackPush(currAddr.and(0xff))
cpu.PC = addr
}
}

13
app/src/main/kotlin/android/emu6502/instructions/impl/RTS.kt Normal file
View File

@ -0,0 +1,13 @@
package android.emu6502.instructions.impl
import android.emu6502.CPU
import android.emu6502.instructions.BaseInstruction
import android.emu6502.instructions.Instruction
/** ReTurn from Subroutine */
class RTS(private val cpu: CPU) : BaseInstruction(Instruction.RTS, cpu.instructionList) {
override fun single() {
cpu.PC = cpu.stackPop().or(cpu.stackPop().shl(8)) + 1
}
}

53
app/src/test/java/android/emu6502/CPUTest.java
View File

@ -1,9 +1,9 @@
package android.emu6502;
import com.google.common.collect.ImmutableList;
import android.emu6502.instructions.Symbols;
import com.google.common.collect.ImmutableList;
import org.junit.Before;
import org.junit.Test;
@ -61,6 +61,7 @@ public class CPUTest {
@Test public void testBranchAndLabel() {
List<String> lines = ImmutableList.of(
"LDX #$08",
"decrement:",
"DEX",
"STX $0200",
@ -77,4 +78,52 @@ public class CPUTest {
assertThat(cpu.getPC(), equalTo(0x060e));
assertThat(cpu.flags(), equalTo("00110011"));
}
@Test public void testJump() {
List<String> lines = ImmutableList.of(
"LDA #$03",
"JMP there",
"BRK",
"BRK",
"BRK",
"there:",
"STA $0200");
assembler.assembleCode(lines);
cpu.execute();
assertThat(cpu.getA(), equalTo(0x03));
assertThat(cpu.getX(), equalTo(0x00));
assertThat(cpu.getY(), equalTo(0x00));
assertThat(cpu.getSP(), equalTo(0xFF));
assertThat(cpu.getPC(), equalTo(0x060c));
assertThat(cpu.flags(), equalTo("00110000"));
}
@Test public void testJumpToSubroutines() {
List<String> lines = ImmutableList.of(
"JSR init",
"JSR loop",
"JSR end",
"init:",
"LDX #$00",
"RTS",
"loop:",
"INX",
"CPX #$05",
"BNE loop",
"RTS",
"end:",
"BRK");
assembler.assembleCode(lines);
cpu.execute();
assertThat(cpu.getA(), equalTo(0x00));
assertThat(cpu.getX(), equalTo(0x05));
assertThat(cpu.getY(), equalTo(0x00));
assertThat(cpu.getSP(), equalTo(0xFD));
assertThat(cpu.getPC(), equalTo(0x0613));
assertThat(cpu.flags(), equalTo("00110011"));
}
}