first public release

r_register_more_prefixes_test.go

@@ -0,0 +1,32 @@
+package z80
+
+import "testing"
+
+func TestR_Increments_On_ED_Neg(t *testing.T) {
+	cpu, mem, _ := testCPU()
+	loadProgram(cpu, mem, 0x0000, 0xED, 0x44) // NEG
+	cpu.R = 0
+	r0 := cpu.R & 0x7F
+	mustStep(t, cpu)
+	r1 := cpu.R & 0x7F
+	// Expect 2 M1s: ED fetch after the initial opcode fetch
+	inc := int((r1 - r0) & 0x7F)
+	if inc != 2 {
+		t.Fatalf("R should increment by 2 for ED-prefixed single op, got %d", inc)
+	}
+}
+
+func TestR_Increments_On_DD_DD_Nop(t *testing.T) {
+	cpu, mem, _ := testCPU()
+	// DD DD <anything> -- our executeDD returns 4 for a second DD as NOP;
+	// we only execute one Step here: first DD, then post-prefix M1 fetches second DD, then stop.
+	loadProgram(cpu, mem, 0x0000, 0xDD, 0xDD)
+	cpu.R = 0
+	r0 := cpu.R & 0x7F
+	mustStep(t, cpu)
+	r1 := cpu.R & 0x7F
+	// Should see 2 M1 increments (first DD fetch + second DD as post-prefix fetch)
+	if int((r1-r0)&0x7F) != 2 {
+		t.Fatalf("R should increment by 2 on DD DD, got %d", int((r1-r0)&0x7F))
+	}
+}