1 files changed, 90 insertions, 2 deletions
diff --git a/src/instruction.spec.ts b/src/instruction.spec.ts
index 0cfaf03..f804a85 100644
--- a/src/instruction.spec.ts
+++ b/src/instruction.spec.ts
@@ -43,7 +43,7 @@ describe('avrInstruction', () => {
 
   it('should execute `OUT 0x3f, r1` instruction', () => {
     loadProgram('1fbe');
-    cpu.data[1] = 0x5a; // put the value 5a in r1
+    cpu.data[1] = 0x5a; // r1 <- 0x5a
     avrInstruction(cpu);
     expect(cpu.pc).toEqual(0x1);
     expect(cpu.cycles).toEqual(1);
@@ -111,7 +111,7 @@ describe('avrInstruction', () => {
 
   it('should execute `ST X+, r1` instruction', () => {
     loadProgram('1d92');
-    cpu.data[1] = 0x5a; // r1 <- 5a
+    cpu.data[1] = 0x5a; // r1 <- 0x5a
     cpu.data[26] = 0x9a; // X <- 0x9a
     avrInstruction(cpu);
     expect(cpu.pc).toEqual(1);
@@ -130,4 +130,92 @@ describe('avrInstruction', () => {
     expect(cpu.data[0x98]).toEqual(0x88);
     expect(cpu.data[26]).toEqual(0x98); // verify that X was decremented
   });
+
+  it('should execute `ST Y, r2` instruction', () => {
+    loadProgram('2882');
+    cpu.data[2] = 0x5b; // r2 <- 0x5b
+    cpu.data[28] = 0x9a; // Y <- 0x9a
+    avrInstruction(cpu);
+    expect(cpu.pc).toEqual(1);
+    expect(cpu.cycles).toEqual(2);
+    expect(cpu.data[0x9a]).toEqual(0x5b);
+    expect(cpu.data[28]).toEqual(0x9a); // verify that Y was unchanged
+  });
+
+  it('should execute `ST Y+, r1` instruction', () => {
+    loadProgram('1992');
+    cpu.data[1] = 0x5a; // r1 <- 5a
+    cpu.data[28] = 0x9a; // Y <- 0x9a
+    avrInstruction(cpu);
+    expect(cpu.pc).toEqual(1);
+    expect(cpu.cycles).toEqual(1);
+    expect(cpu.data[0x9a]).toEqual(0x5a);
+    expect(cpu.data[28]).toEqual(0x9b); // verify that Y was incremented
+  });
+
+  it('should execute `ST -Y, r1` instruction', () => {
+    loadProgram('1a92');
+    cpu.data[1] = 0x5a; // r1 <- 5a
+    cpu.data[28] = 0x9a; // Y <- 0x9a
+    avrInstruction(cpu);
+    expect(cpu.pc).toEqual(1);
+    expect(cpu.cycles).toEqual(2);
+    expect(cpu.data[0x99]).toEqual(0x5a);
+    expect(cpu.data[28]).toEqual(0x99); // verify that Y was decremented
+  });
+
+  it('should execute `STD Y+17, r0` instruction', () => {
+    loadProgram('098a');
+    cpu.data[0] = 0xba; // r0 <- ba
+    cpu.data[28] = 0x9a; // Y <- 0x9a
+    avrInstruction(cpu);
+    expect(cpu.pc).toEqual(1);
+    expect(cpu.cycles).toEqual(2);
+    expect(cpu.data[0x9a + 17]).toEqual(0xba);
+    expect(cpu.data[28]).toEqual(0x9a); // verify that Y was unchanged
+  });
+
+  it('should execute `ST Z, r16` instruction', () => {
+    loadProgram('0083');
+    cpu.data[16] = 0xdf; // r2 <- 0xdf
+    cpu.data[30] = 0x40; // Z <- 0x40
+    avrInstruction(cpu);
+    expect(cpu.pc).toEqual(1);
+    expect(cpu.cycles).toEqual(2);
+    expect(cpu.data[0x40]).toEqual(0xdf);
+    expect(cpu.data[30]).toEqual(0x40); // verify that Z was unchanged
+  });
+
+  it('should execute `ST Z+, r0` instruction', () => {
+    loadProgram('0192');
+    cpu.data[0] = 0x55; // r0 <- 0x55
+    cpu.dataView.setUint16(30, 0x155, true); // Z <- 0x155
+    avrInstruction(cpu);
+    expect(cpu.pc).toEqual(1);
+    expect(cpu.cycles).toEqual(1);
+    expect(cpu.data[0x155]).toEqual(0x55);
+    expect(cpu.dataView.getUint16(30, true)).toEqual(0x156); // verify that Z was incremented
+  });
+
+  it('should execute `ST -Z, r16` instruction', () => {
+    loadProgram('0293');
+    cpu.data[16] = 0x5a; // r16 <- 0x5a
+    cpu.data[30] = 0xff; // Z <- 0xff
+    avrInstruction(cpu);
+    expect(cpu.pc).toEqual(1);
+    expect(cpu.cycles).toEqual(2);
+    expect(cpu.data[0xfe]).toEqual(0x5a);
+    expect(cpu.data[30]).toEqual(0xfe); // verify that Z was decremented
+  });
+
+  it('should execute `STD Z+1, r0` instruction', () => {
+    loadProgram('0182');
+    cpu.data[0] = 0xcc; // r0 <- 0xcc
+    cpu.data[30] = 0x50; // Z <- 0x50
+    avrInstruction(cpu);
+    expect(cpu.pc).toEqual(1);
+    expect(cpu.cycles).toEqual(2);
+    expect(cpu.data[0x51]).toEqual(0xcc);
+    expect(cpu.data[30]).toEqual(0x50); // verify that Z was unchanged
+  });
 });