dForth

commit b85f968aa25b96bc869a908dc229104d65bde105
parent a810762abd78929e5af31822e8061131526e45aa
Author: Pavel Renev <an2qzavok@gmail.com>
Date:   Sat, 30 Oct 2021 21:52:04 +0000

add forth.Step()

Diffstat:
M
dForth.go
 | 
32
+++++++++++++++++++++++++-------

1 file changed, 25 insertions(+), 7 deletions(-)
diff --git a/dForth.go b/dForth.go
@@ -23,7 +23,7 @@ const (
 type Word struct {
 	Name string
 	Builtin func() error
-	Code []int
+	Addr int32
 }
 
 func NewWord(name string, builtin func() error) *Word {
@@ -33,10 +33,6 @@ func NewWord(name string, builtin func() error) *Word {
 	return word
 }
 
-func (word *Word) Compile(codes ...int) {
-	word.Code = append(word.Code, codes...)
-}
-
 type Forth struct {
 	Dict []*Word
 	Mem []byte
@@ -61,7 +57,11 @@ func NewForth() *Forth {
 	_ = forth.memStore(dtpt, dictstart)
 	_ = forth.memStore(lwpt, 0)
 	_ = forth.memStore(pcpt, dictstart)
-	forth.memCompile(0, 2, dictstart, 3)
+	forth.memCompile(
+	  0,             /* _read         */
+	  2, dictstart, /* _lit dictstart */
+	  3,            /* _jump          */
+	)
 	return forth
 }
 
@@ -93,6 +93,24 @@ func (forth *Forth) memCompile(codes ...int32) {
 	forth.memStore(dtpt, int32(int(dt) + len(codes) * 4))
 }
 
+func (forth *Forth) Step() error {
+	pc, _ := forth.memFetch(pcpt);
+	inst, _ := forth.memFetch(pc);
+	pc++;
+	if (inst > 0) && (int(inst) < len(forth.Dict)) {
+		w := forth.Dict[inst]
+		if w.Builtin != nil {
+			return w.Builtin()
+		} else {
+			pc = w.Addr
+		}
+	} else {
+		return fmt.Errorf("invalid instruction: %d, pc %d", inst, pc - 1);
+	}
+	_ = forth.memStore(pcpt, pc);
+	return nil
+}
+
 func (forth *Forth) Push(pt, val int32) {
 	tos, err := forth.memFetch(pt)
 	if err != nil {
@@ -227,6 +245,6 @@ func (forth *Forth) biJump() error {
 func main() {
 	fmt.Println("Welcome to dForth.")
 	forth := NewForth()
-	for forth.biRead() == nil {
+	for forth.Step() == nil {
 	}
 }