Working disassembler

asm/disassemble.go

@@ -1,39 +1,91 @@
 package asm
 
 import "fmt"
+import "math"
 import "strings"
 
 import "github.com/firestuff/subcoding/vm"
 import "github.com/pkg/errors"
 
-func Disassemble(prog *vm.Program) ([]byte, error) {
+// Lots of manual yaml assembly because the yaml package is missing features (flow in nested arrays)
+
+func Disassemble(prog *vm.Program) (string, error) {
+	fncs := []string{}
+
 	for f, fnc := range prog.Functions {
-		_, err := disassembleFunction(fnc)
+		dis, err := disassembleFunction(fnc)
 		if err != nil {
-			return nil, errors.Wrapf(err, "At function index %d", f)
+			return "", errors.Wrapf(err, "At function index %d", f)
 		}
+
+		fncs = append(fncs, dis)
 	}
 
-	return nil, nil
+	return fmt.Sprintf("functions:\n%s", strings.Join(fncs, "")), nil
 }
 
-func disassembleFunction(fnc *vm.Function) ([]byte, error) {
+func disassembleFunction(fnc *vm.Function) (string, error) {
+	instrs := []string{}
+
 	for i, instr := range fnc.Instructions {
-		_, err := disassembleInstruction(instr)
+		dis, err := disassembleInstruction(instr)
 		if err != nil {
-			return nil, errors.Wrapf(err, "At instruction index %d", i)
+			return "", errors.Wrapf(err, "At instruction index %d", i)
 		}
+
+		instrs = append(instrs, dis)
 	}
 
-	return nil, nil
+	return fmt.Sprintf("- - %s\n", strings.Join(instrs, "\n  - ")), nil
 }
 
-func disassembleInstruction(in *vm.Instruction) ([]byte, error) {
+func disassembleInstruction(in *vm.Instruction) (string, error) {
 	parts := []string{
 		nameByOpCode[in.OpCode],
 	}
 
+	for i, t := range operandsByOpCode[in.OpCode] {
+		op, err := disassembleOperand(in.Operands[i], t)
+		if err != nil {
+			return "", err
+		}
+
+		parts = append(parts, op)
+	}
+
 	encoded := fmt.Sprintf("[%s]", strings.Join(parts, ", "))
 
-	return []byte(encoded), nil
+	return encoded, nil
+}
+
+func disassembleOperand(op *vm.Operand, t operandType) (string, error) {
+	switch op.Type {
+	case vm.GlobalMemoryIndex:
+		return fmt.Sprintf("g%d", op.Value), nil
+
+	case vm.FunctionMemoryIndex:
+		return fmt.Sprintf("f%d", op.Value), nil
+
+	case vm.Literal:
+		switch t {
+		case u:
+			return fmt.Sprintf("%d", op.Value), nil
+
+		case s:
+			return fmt.Sprintf("%+d", int64(op.Value)), nil
+
+		case us:
+			// Take our best guess
+			if op.Value > math.MaxInt64 {
+				return fmt.Sprintf("%+d", int64(op.Value)), nil
+			} else {
+				return fmt.Sprintf("%d", op.Value), nil
+			}
+		default:
+			return "", fmt.Errorf("Invalid operand assembler type: %d", t)
+		}
+
+	default:
+		return "", fmt.Errorf("Invalid operand type: %d", op.Type)
+	}
 }

test/disasm_test.go

@@ -5,16 +5,27 @@ import "testing"
 import "github.com/firestuff/subcoding/asm"
 
 func TestRoundTrip(t *testing.T) {
-	prog, err := asm.AssembleString(`
+	src := `functions:
-functions:
 - - [nop]
-`)
+  - [mov, g0, 1]
+  - [add, f0, 5]
+  - [mov, g1, -5]
+  - [eq, 2, f0]
+  - [jmpt, -3]
+- - [add, g0, -1]
+  - [cal, +5]
+`
+	prog, err := asm.AssembleString(src)
 	if err != nil {
 		t.Fatal(err)
 	}
 
-	_, err = asm.Disassemble(prog)
+	dis, err := asm.Disassemble(prog)
 	if err != nil {
 		t.Fatal(err)
 	}
+
+	if dis != src {
+		t.Fatalf("Disassembly mismatch: expected=%v actual=%v", src, dis)
+	}
 }