Split out the loader from the VM

load/load.go

@@ -0,0 +1,54 @@
+package load
+
+import "bytes"
+
+import "github.com/firestuff/subcoding/vm"
+import "github.com/lunixbochs/struc"
+import "github.com/pkg/errors"
+
+const instructionBytes = 32
+
+func Load(byteCodes [][]byte) ([][]*vm.Instruction, error) {
+	fncs := [][]*vm.Instruction{}
+
+	for i, byteCode := range byteCodes {
+		instrs, err := loadFunction(byteCode)
+		if err != nil {
+			return nil, errors.Wrapf(err, "At function index %d", i)
+		}
+
+		fncs = append(fncs, instrs)
+	}
+
+	return fncs, nil
+}
+
+func loadFunction(byteCode []byte) ([]*vm.Instruction, error) {
+	instrs := []*vm.Instruction{}
+
+	for start := 0; start < len(byteCode); start += instructionBytes {
+		chunk := byteCode[start : start+instructionBytes]
+
+		instr, err := loadInstruction(chunk)
+		if err != nil {
+			return nil, errors.Wrapf(err, "At byte offset %d", start)
+		}
+
+		instrs = append(instrs, instr)
+	}
+
+	return instrs, nil
+}
+
+func loadInstruction(byteCode []byte) (*vm.Instruction, error) {
+	instr := &vm.Instruction{}
+
+	reader := bytes.NewReader(byteCode)
+
+	err := struc.Unpack(reader, instr)
+	if err != nil {
+		return nil, errors.Wrap(err, "Error decoding instruction")
+	}
+
+	return instr, nil
+}