opcode - waiting for key pressed - implementation fixed, simplified a…

…nd fully tested
tomekbielaszewski · Aug 9, 2018 · d06ee5c · d06ee5c
1 parent 3d003d2
commit d06ee5c
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Showing 2 changed files with 23 additions and 18 deletions.
diff --git a/src/main/java/pl/grizwold/chip8/emulator/opcodes/Opcode_FX0A.java b/src/main/java/pl/grizwold/chip8/emulator/opcodes/Opcode_FX0A.java
@@ -13,8 +13,10 @@ public boolean accept(short code) {
     public void execute(short code, VirtualMachine vm) {
         short x = (short) ((code & 0x0F00) >>> 8);
 
-        while (!isKeyPressed(vm.keyboard)) {
+        if(isKeyPressed(vm.keyboard)) {
             vm.V[x] = getKeyValue(vm.keyboard);
+        } else {
+            vm.PC -= 2;
         }
     }
 

diff --git a/src/test/java/pl/grizwold/chip8/emulator/opcodes/Opcode_FX0ATest.java b/src/test/java/pl/grizwold/chip8/emulator/opcodes/Opcode_FX0ATest.java
@@ -21,30 +21,33 @@ public void shouldAcceptCode() throws Exception {
         assertTrue(opcode.accept(code));
     }
 
-    @Test(timeout = 1000)
-    public void shouldWaitForKeystroke() throws Exception {
+    @Test
+    public void shouldDecrementProgramCounterWhenKeyIsNotPressed() throws Exception {
         short code = (short) 0xFA0A;
         byte vxBefore = 0xf;
+        vm.keyboard = 0;
         vm.V[0xA] = vxBefore;
-        boolean[] isKeypressed = {false};
-
-        ExecutorService executor = Executors.newSingleThreadExecutor();
-
-        executor.execute(() -> {
-            sleep(500);
-
-            isKeypressed[0] = true;
-            vm.keyboard = 0b1 << 5;
-        });
+        vm.PC = 100;
 
         opcode.execute(code, vm);
 
-        if (!isKeypressed[0]) fail();
-        assertTrue(vm.V[0xA] == 6);
+        assertTrue(vm.V[0xA] == vxBefore);
+        assertTrue(vm.PC == 98);
     }
 
-    @SneakyThrows
-    private void sleep(long time) {
-        Thread.sleep(time);
+    @Test
+    public void shouldSetRegisterToKeyCodeWhenKey_x_IsPressed() throws Exception {
+        for (int i = 0; i < 16; i++) {
+            short code = (short) 0xFA0A;
+            byte vxBefore = 0xf;
+            vm.keyboard = (short) ((0b1 << i) & 0xFFFF);
+            vm.V[0xA] = vxBefore;
+            vm.PC = 100;
+
+            opcode.execute(code, vm);
+
+            assertTrue(vm.V[0xA] == i + 1);
+            assertTrue(vm.PC == 100);
+        }
     }
 }