| 1 | package com.rox.apu; | |
| 2 | ||
| 3 | import com.rox.clock.ClockWatcher; | |
| 4 | ||
| 5 | /** | |
| 6 | * Every other call to {@link #tick()}, counts down from {@link #getCounterPeriod()} to 0 then | |
| 7 | * executes the given action - the "do real work on every other CPU cycle" gating that pulse and | |
| 8 | * noise channel timers both need (one APU cycle = two CPU cycles). | |
| 9 | * | |
| 10 | * Whether the very first call already counts as an "active" one (and so can run the action | |
| 11 | * immediately, if the countdown is already at 0) is set via the constructor's | |
| 12 | * {@code initialParityGate} argument, which seeds {@link #parityGate}. | |
| 13 | */ | |
| 14 | public class ParityCountdownFrequencyDivider implements ClockWatcher { | |
| 15 | private final Runnable action; | |
| 16 | ||
| 17 | private boolean parityGate; | |
| 18 | private int countdown; | |
| 19 | private int counterPeriod; | |
| 20 | ||
| 21 | public ParityCountdownFrequencyDivider(final Runnable action, | |
| 22 | final boolean initialParityGate, | |
| 23 | final int counterPeriod) { | |
| 24 |
2
1. <init> : negated conditional → KILLED 2. <init> : changed conditional boundary → KILLED |
if (counterPeriod < 0){ |
| 25 | throw new IllegalArgumentException("Period must be non-negative since it's a decreasing count that ends at 0."); | |
| 26 | } | |
| 27 | ||
| 28 | this.action = action; | |
| 29 | this.parityGate = initialParityGate; | |
| 30 | this.counterPeriod = counterPeriod; | |
| 31 | } | |
| 32 | ||
| 33 | public int getCounterPeriod() { | |
| 34 |
1
1. getCounterPeriod : replaced int return with 0 for com/rox/apu/ParityCountdownFrequencyDivider::getCounterPeriod → KILLED |
return counterPeriod; |
| 35 | } | |
| 36 | ||
| 37 | public void setCounterPeriod(final int newCounterPeriod) { | |
| 38 |
2
1. setCounterPeriod : changed conditional boundary → KILLED 2. setCounterPeriod : negated conditional → KILLED |
if (newCounterPeriod < 0){ |
| 39 | throw new IllegalArgumentException("Period must be non-negative since it's a decreasing count that ends at 0."); | |
| 40 | } | |
| 41 | ||
| 42 | this.counterPeriod = newCounterPeriod; | |
| 43 | } | |
| 44 | ||
| 45 | /** Toggle the parity boolean and return the result */ | |
| 46 | private boolean toggleParityAndGet(){ | |
| 47 |
1
1. toggleParityAndGet : negated conditional → KILLED |
parityGate = !parityGate; |
| 48 |
2
1. toggleParityAndGet : replaced boolean return with false for com/rox/apu/ParityCountdownFrequencyDivider::toggleParityAndGet → KILLED 2. toggleParityAndGet : replaced boolean return with true for com/rox/apu/ParityCountdownFrequencyDivider::toggleParityAndGet → KILLED |
return parityGate; |
| 49 | } | |
| 50 | ||
| 51 | @Override | |
| 52 | public void tick() { | |
| 53 | //Only actions half the time, effectively dividing by 2 | |
| 54 |
1
1. tick : negated conditional → KILLED |
if (toggleParityAndGet()){ |
| 55 | //Counts down from `counterPeriod` using `countdown`, firing `action` when we reach zero | |
| 56 |
1
1. tick : negated conditional → KILLED |
if (countdown == 0){ |
| 57 | countdown = counterPeriod; | |
| 58 |
1
1. tick : removed call to java/lang/Runnable::run → KILLED |
action.run(); |
| 59 | } else { | |
| 60 |
1
1. tick : Replaced integer subtraction with addition → KILLED |
countdown--; |
| 61 | } | |
| 62 | } | |
| 63 | } | |
| 64 | ||
| 65 | /** Everything a {@link ParityCountdownFrequencyDivider} needs to carry on exactly where it was (its action is wiring, not state). */ | |
| 66 | public record Snapshot(boolean parityGate, int countdown, int counterPeriod) { | |
| 67 | } | |
| 68 | ||
| 69 | public Snapshot snapshot(){ | |
| 70 |
1
1. snapshot : replaced return value with null for com/rox/apu/ParityCountdownFrequencyDivider::snapshot → KILLED |
return new Snapshot(parityGate, countdown, counterPeriod); |
| 71 | } | |
| 72 | ||
| 73 | public void restore(final Snapshot snapshot){ | |
| 74 | parityGate = snapshot.parityGate(); | |
| 75 | countdown = snapshot.countdown(); | |
| 76 | counterPeriod = snapshot.counterPeriod(); | |
| 77 | } | |
| 78 | } | |
Mutations | ||
| 24 |
1.1 2.2 |
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| 34 |
1.1 |
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| 38 |
1.1 2.2 |
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| 47 |
1.1 |
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| 48 |
1.1 2.2 |
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| 54 |
1.1 |
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| 56 |
1.1 |
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| 58 |
1.1 |
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| 60 |
1.1 |
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| 70 |
1.1 |