Add * and / operators, VM step debugger, and visualizer tweaks

Support multiply and divide in lexer, parser and eval.
Add step-by-step VM debug output with AST and heap visualization.
Remove spacing in visualizer hex output.

projects/resta.j

@@ -0,0 +1,5 @@
+x=2
+y=5
+z = x + y
+zz = z * x
+print zz

src/frontend/lexer.h

@@ -81,6 +81,12 @@ Token *tokenize(const char *source, int *token_count) {
     } else if (c == '-') {
       tokens[count++] = make_token(TOK_MINUS, "-");
       pos++;
+    } else if (c == '*') {
+      tokens[count++] = make_token(TOK_STAR, "*");
+      pos++;
+    } else if (c == '/') {
+      tokens[count++] = make_token(TOK_SLASH, "/");
+      pos++;
     } else if (c == '=') {
       tokens[count++] = make_token(TOK_ASSIGN, "=");
       pos++;

src/frontend/parser.h

@@ -80,9 +80,9 @@ ASTNode *parse_expr(Token *tokens)
 {
     ASTNode *left = parse_term(tokens);
 
-    while (tokens[pos].type == TOK_PLUS || tokens[pos].type == TOK_MINUS)
+    while (tokens[pos].type == TOK_PLUS || tokens[pos].type == TOK_MINUS || tokens[pos].type == TOK_STAR || tokens[pos].type == TOK_SLASH)
     {
-        char op = tokens[pos].value[0]; // + o -
+        char op = tokens[pos].value[0]; // +,-,*,/
         pos++;
         ASTNode *right = parse_term(tokens);
 

src/memory/allocator.h

@@ -199,7 +199,8 @@ void JLANG_visualize(void *ptr) {
         }
       } else {
         // Mark all block as JLANG_NOT_USE
-        memset(byteMapPtr + blockIndex, JLANG_NOT_USE, sizeof(JLANG_metadata) + currentHeader->size);
+        memset(byteMapPtr + blockIndex, JLANG_NOT_USE,
+               sizeof(JLANG_metadata) + currentHeader->size);
       }
     } else {
       break;
@@ -215,7 +216,6 @@ void JLANG_visualize(void *ptr) {
 
   int bytePerRow = 40;
   int totalRows = _ceil(allocPtr->size / bytePerRow);
-  printf("totalRows=%d\n", totalRows);
 
   char *currentMemPtr = allocPtr->memory;
 
@@ -242,9 +242,11 @@ void JLANG_visualize(void *ptr) {
 
       printf("%.2x", (unsigned char)*(currentMemPtr + (n + i * bytePerRow)));
 
+      /*
         if (n < bytePerRow - 1) {
           printf(" ");
         }
+      */
 
       printf("\033[0m");
     }

src/vm/eval.h

@@ -44,7 +44,16 @@ void env_set(Environment *env, const char *name, size_t value)
     env->count++;
 }
 
+int step = 0;
+
 size_t eval(ASTNode *node, Environment *env, void *allocator) {
+    step++;
+    printf("===== VM Step: %d =====\n", step);
+    printf("executing node:\n");
+    ast_debug(node);
+    printf("\n");
+    JLANG_visualize(allocator);
+
     switch (node->type) {
         case NODE_INT_LIT:
             return obj_new_int(allocator, node->data.int_val);
@@ -68,6 +77,10 @@ size_t eval(ASTNode *node, Environment *env, void *allocator) {
                 return obj_new_int(allocator, l->data.int_val + r->data.int_val);
             } else if (node->data.binop.op == '-') {
                 return obj_new_int(allocator, l->data.int_val - r->data.int_val);
+            } else if (node->data.binop.op == '*') {
+                return obj_new_int(allocator, l->data.int_val * r->data.int_val);
+            } else if (node->data.binop.op == '/') {
+                return obj_new_int(allocator, l->data.int_val / r->data.int_val);
             } 
         }
         case NODE_PRINT: {