init

vm/vm_test.go

@@ -0,0 +1,114 @@
+package vm
+
+import "testing"
+
+type testBus struct {
+	in  map[uint16]int32
+	out map[uint16]int32
+}
+
+func (b *testBus) In(p uint16) int32     { return b.in[p] }
+func (b *testBus) Out(p uint16, v int32) { b.out[p] = v }
+
+func run(t *testing.T, src string, budget int) (*CPU, *testBus) {
+	t.Helper()
+	prog, err := Assemble(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	c, err := New(prog, 256)
+	if err != nil {
+		t.Fatal(err)
+	}
+	b := &testBus{in: map[uint16]int32{5: 42}, out: map[uint16]int32{}}
+	c.Run(b, budget)
+	return c, b
+}
+
+func TestSumLoop(t *testing.T) {
+	c, b := run(t, `
+		ldi r0, 0      ; sum
+		ldi r1, 1      ; i
+		ldi r2, 11
+	loop:
+		add r0, r1
+		addi r1, 1
+		blt r1, r2, loop
+		out 7, r0
+		halt
+	`, 1000)
+	if c.Status != Halted || b.out[7] != 55 {
+		t.Fatalf("status=%v out=%d", c.Status, b.out[7])
+	}
+}
+
+func TestLiCallStackMemory(t *testing.T) {
+	c, b := run(t, `
+		li r0, 0x12345678
+		call double
+		stw r0, [sp-8]   ; below current sp
+		ldw r3, [sp-8]
+		in r4, 5
+		add r3, r4
+		out 1, r3
+		halt
+	double:
+		add r0, r0
+		ret
+	`, 1000)
+	want := int32(0x12345678)*2 + 42
+	if c.Status != Halted || b.out[1] != want {
+		t.Fatalf("status=%v fault=%q out=%x want %x", c.Status, c.Fault, b.out[1], want)
+	}
+}
+
+func TestYieldAndBudget(t *testing.T) {
+	prog, _ := Assemble("l: addi r0, 1\n jmp l")
+	c, _ := New(prog, 64)
+	b := &testBus{}
+	if used := c.Run(b, 100); used != 100 || c.Status != Running {
+		t.Fatalf("used=%d status=%v", used, c.Status)
+	}
+	r0 := c.R[0]
+	c.Run(b, 100)
+	if c.R[0] != r0+50 {
+		t.Fatalf("did not resume: %d -> %d", r0, c.R[0])
+	}
+}
+
+func TestFaults(t *testing.T) {
+	c, _ := run(t, "ldi r0, 1\n ldi r1, 0\n div r0, r1", 100)
+	if c.Status != Faulted {
+		t.Fatal("expected div fault")
+	}
+	c, _ = run(t, "ldi r1, 300\n ldw r0, [r1]", 100)
+	if c.Status != Faulted {
+		t.Fatal("expected memory fault")
+	}
+}
+
+func TestStateRoundTrip(t *testing.T) {
+	c, _ := run(t, "ldi r0, 9\n stb r0, [r1+3]\n yield\n ldi r0, 1", 100)
+	d, _ := New(c.Prog, 256)
+	if err := d.UnmarshalState(c.MarshalState()); err != nil {
+		t.Fatal(err)
+	}
+	if d.R != c.R || d.PC != c.PC || d.RAM[3] != 9 || d.Status != Yielded {
+		t.Fatal("state mismatch")
+	}
+}
+
+func TestAssemblerCaseInsensitiveDirectives(t *testing.T) {
+	// LI expands to two instructions; label distances must agree in any case.
+	lower, err := Assemble(".equ K 5\n li r1, 0x12345\n jmp end\n nop\nend: halt")
+	if err != nil {
+		t.Fatal(err)
+	}
+	upper, err := Assemble(".EQU K 5\n LI r1, 0x12345\n JMP end\n NOP\nend: HALT")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(lower) != string(upper) {
+		t.Fatal("upper- and lower-case source assembled differently")
+	}
+}