fix: correct Cell union and add interpreter, main, word implementations

Co-authored-by: aider (openrouter/tencent/hy3-preview:free) <aider@aider.chat>

forth.h

@@ -24,7 +24,7 @@ typedef struct Word Word;
 typedef union Cell {
     Word* word;
     int32_t num;
-    Cell* cell_ptr; // For storing ip (Cell*) in return stack
+    union Cell* cell_ptr; // Use union tag here, as typedef Cell is not available yet
 } Cell;
 
 struct Word {

forth_interp.c

@@ -0,0 +1,97 @@
+#include "forth.h"
+
+// Input tokenizer
+char* next_token(void) {
+    if (input_ptr == NULL) return NULL;
+    while (*input_ptr != '\0' && isspace((unsigned char)*input_ptr)) {
+        input_ptr++;
+    }
+    if (*input_ptr == '\0') return NULL;
+    char* start = input_ptr;
+    while (*input_ptr != '\0' && !isspace((unsigned char)*input_ptr)) {
+        input_ptr++;
+    }
+    if (*input_ptr != '\0') {
+        *input_ptr = '\0';
+        input_ptr++;
+    }
+    return start;
+}
+
+// Interpreter functions
+void inner_interpreter(void) {
+    while (ip != NULL) {
+        Cell current = *ip;
+        ip++; // Move to next cell
+        current.word->code(current.word);
+    }
+}
+
+void process_token(const char* token) {
+    Word* w = lookup_word(token);
+    if (w != NULL) {
+        if (state == 0) { // Interpret mode
+            if (w->code == do_docolon) { // Colon definition
+                ret_push(NULL); // Return address to stop interpreter
+                ip = w->body;
+                inner_interpreter();
+            } else { // Primitive word
+                w->code(w);
+            }
+        } else { // Compile mode
+            if (w->flags & (1 << 7)) { // Immediate word: execute now
+                if (w->code == do_docolon) {
+                    ret_push(NULL);
+                    ip = w->body;
+                    inner_interpreter();
+                } else {
+                    w->code(w);
+                }
+            } else { // Normal word: compile into current definition
+                if (compile_idx >= COMPILE_BUF_SIZE) {
+                    printf("Compile buffer full\n");
+                    return;
+                }
+                compile_buf[compile_idx++] = (Cell){.word = w};
+            }
+        }
+    } else { // Not a known word: try to parse as number
+        char* end;
+        long v = strtol(token, &end, 10);
+        if (end != token && *end == '\0') { // Valid integer
+            if (state == 0) { // Interpret mode: push number
+                data_push((int32_t)v);
+            } else { // Compile mode: compile lit + number
+                Word* lit_w = lookup_word("lit");
+                if (lit_w == NULL) {
+                    printf("Fatal: lit word not found\n");
+                    return;
+                }
+                if (compile_idx + 2 > COMPILE_BUF_SIZE) {
+                    printf("Compile buffer full\n");
+                    return;
+                }
+                compile_buf[compile_idx++] = (Cell){.word = lit_w};
+                compile_buf[compile_idx++] = (Cell){.num = (int32_t)v};
+            }
+        } else {
+            printf("Unknown word: '%s'\n", token);
+        }
+    }
+}
+
+void outer_interpreter(void) {
+    while (1) {
+        printf("ok ");
+        fflush(stdout);
+        if (fgets(input_buf, INPUT_BUF_SIZE, stdin) == NULL) {
+            break; // EOF
+        }
+        input_ptr = input_buf;
+        char* tok;
+        while ((tok = next_token()) != NULL) {
+            process_token(tok);
+        }
+    }
+    printf("\n");
+}

forth_words.c

@@ -293,4 +293,214 @@ void do_key(Word* w) {
 void do_dot_quote(Word* w) {
     // Immediate word: parse string until " and print/compile
     if (state == 0) { // Interpret mode: print immediately
-        //
+        if (input_ptr == NULL) {
+            printf("Missing string\n");
+            return;
+        }
+        // Skip whitespace before opening "
+        while (*input_ptr != '\0' && isspace((unsigned char)*input_ptr)) {
+            input_ptr++;
+        }
+        if (*input_ptr != '"') {
+            printf("Expected \" to start string\n");
+            return;
+        }
+        input_ptr++; // Skip opening "
+        char* start = input_ptr;
+        // Find closing "
+        while (*input_ptr != '\0' && *input_ptr != '"') {
+            input_ptr++;
+        }
+        if (*input_ptr != '"') {
+            printf("Unterminated string\n");
+            return;
+        }
+        // Print the string
+        while (start < input_ptr) {
+            putchar(*start++);
+        }
+        input_ptr++; // Skip closing "
+        fflush(stdout);
+    } else { // Compile mode: compile string for runtime
+        if (input_ptr == NULL) {
+            printf("Missing string\n");
+            return;
+        }
+        // Skip whitespace before opening "
+        while (*input_ptr != '\0' && isspace((unsigned char)*input_ptr)) {
+            input_ptr++;
+        }
+        if (*input_ptr != '"') {
+            printf("Expected \" to start string\n");
+            return;
+        }
+        input_ptr++; // Skip opening "
+        char* start = input_ptr;
+        // Find closing "
+        while (*input_ptr != '\0' && *input_ptr != '"') {
+            input_ptr++;
+        }
+        if (*input_ptr != '"') {
+            printf("Unterminated string\n");
+            return;
+        }
+        size_t len = input_ptr - start;
+        // Compile do_dot_quote_inner
+        Word* inner_w = lookup_word("do_dot_quote_inner");
+        if (inner_w == NULL) {
+            printf("Fatal: do_dot_quote_inner not found\n");
+            return;
+        }
+        if (compile_idx + 2 + len > COMPILE_BUF_SIZE) {
+            printf("Compile buffer full\n");
+            return;
+        }
+        compile_buf[compile_idx++] = (Cell){.word = inner_w};
+        compile_buf[compile_idx++] = (Cell){.num = (int32_t)len};
+        // Store string characters in compile buffer (each as a num cell)
+        for (size_t i = 0; i < len; i++) {
+            compile_buf[compile_idx++] = (Cell){.num = (int32_t)start[i]};
+        }
+        input_ptr++; // Skip closing "
+    }
+}
+
+void do_dot_quote_inner(Word* w) {
+    // Runtime: ip points to length cell, followed by string characters
+    int32_t len = ip->num;
+    ip++;
+    for (int32_t i = 0; i < len; i++) {
+        putchar((char)ip->num);
+        ip++;
+    }
+    fflush(stdout);
+}
+
+void do_words(Word* w) {
+    printf("Dictionary words:\n");
+    for (Word* cur = dict_head; cur != NULL; cur = cur->prev) {
+        if (cur->flags & (1 << 6)) continue; // Skip hidden
+        printf("%s ", cur->name);
+    }
+    printf("\n");
+    fflush(stdout);
+}
+
+// Control flow operations
+void do_exit(Word* w) {
+    Cell* ret_addr = ret_pop_ip();
+    ip = ret_addr;
+}
+
+void do_docolon(Word* w) {
+    // Push current ip (return address) onto return stack
+    ret_push_ip(ip);
+    // Set ip to this word's body
+    ip = w->body;
+}
+
+void do_lit(Word* w) {
+    // ip points to the number cell (inner interpreter already incremented past lit word)
+    data_push(ip->num);
+    ip++; // Move past number cell
+}
+
+void do_colon(Word* w) {
+    char* name = next_token();
+    if (name == NULL) {
+        printf("':' expects a name\n");
+        return;
+    }
+    strncpy(compiling_name, name, MAX_NAME_LEN);
+    compiling_name[MAX_NAME_LEN] = '\0';
+    state = 1; // Enter compile mode
+    compile_idx = 0; // Reset compile buffer
+}
+
+void do_semicolon(Word* w) {
+    if (state != 1) {
+        printf("';' is only valid in compile mode\n");
+        return;
+    }
+    Word* exit_w = lookup_word("exit");
+    if (exit_w == NULL) {
+        printf("Fatal: exit word not found\n");
+        return;
+    }
+    if (compile_idx >= COMPILE_BUF_SIZE) {
+        printf("Compile buffer overflow\n");
+        return;
+    }
+    compile_buf[compile_idx++] = (Cell){.word = exit_w};
+
+    // Copy compiled body to dictionary body storage
+    if (body_idx + compile_idx > BODY_SIZE) {
+        printf("Dictionary body storage full\n");
+        return;
+    }
+    memcpy(&dict_bodies[body_idx], compile_buf, compile_idx * sizeof(Cell));
+
+    // Create new word entry
+    if (dict_idx >= DICT_SIZE) {
+        printf("Dictionary full\n");
+        return;
+    }
+    Word* new_w = &dict[dict_idx++];
+    new_w->prev = dict_head;
+    dict_head = new_w;
+
+    size_t len = strlen(compiling_name);
+    if (len > MAX_NAME_LEN) len = MAX_NAME_LEN;
+    new_w->flags = (uint8_t)len; // No hidden, no immediate
+    strncpy(new_w->name, compiling_name, len);
+    new_w->name[len] = '\0';
+    new_w->code = do_docolon;
+    new_w->body = &dict_bodies[body_idx];
+
+    body_idx += compile_idx;
+    state = 0; // Back to interpret mode
+}
+
+void do_branch(Word* w) {
+    // Unconditional branch: ip points to offset cell
+    int32_t offset = ip->num;
+    ip += offset; // Jump offset cells (offset is relative to after the offset cell)
+}
+
+void do_zero_branch(Word* w) {
+    // Conditional branch: if top of stack is 0, branch
+    int32_t cond = data_pop();
+    if (cond == 0) {
+        int32_t offset = ip->num;
+        ip += offset;
+    } else {
+        ip++; // Skip offset cell
+    }
+}
+
+// Memory operations (stubs for now)
+void do_fetch(Word* w) { /* TODO */ }
+void do_store(Word* w) { /* TODO */ }
+void do_plus_store(Word* w) { /* TODO */ }
+void do_cfetch(Word* w) { /* TODO */ }
+void do_cstore(Word* w) { /* TODO */ }
+void do_variable(Word* w) { /* TODO */ }
+void do_constant(Word* w) { /* TODO */ }
+void do_do_var(Word* w) { /* TODO */ }
+void do_do_const(Word* w) { /* TODO */ }
+void do_here(Word* w) { /* TODO */ }
+void do_allot(Word* w) { /* TODO */ }
+
+// Return stack operations (stubs for now)
+void do_to_r(Word* w) { /* TODO */ }
+void do_r_from(Word* w) { /* TODO */ }
+void do_r_fetch(Word* w) { /* TODO */ }
+
+// Additional control flow stubs
+void do_if(Word* w) { /* TODO */ }
+void do_else(Word* w) { /* TODO */ }
+void do_then(Word* w) { /* TODO */ }
+void do_begin(Word* w) { /* TODO */ }
+void do_until(Word* w) { /* TODO */ }
+void do_while(Word* w) { /* TODO */ }
+void do_repeat(Word* w) { /* TODO */ }

main.c

@@ -0,0 +1,74 @@
+#include "forth.h"
+
+int main(void) {
+    // Register primitive words
+    // Hidden words first
+    add_primitive("exit", do_exit, 0);
+    add_primitive("docolon", do_docolon, 1 << 6); // Hidden
+    add_primitive("lit", do_lit, 1 << 6); // Hidden
+    add_primitive("do_dot_quote_inner", do_dot_quote_inner, 1 << 6); // Hidden
+    add_primitive("0branch", do_zero_branch, 1 << 6); // Hidden (for IF)
+    add_primitive("branch", do_branch, 1 << 6); // Hidden (for ELSE, BEGIN)
+
+    // Public primitives
+    // Stack ops
+    add_primitive("dup", do_dup, 0);
+    add_primitive("drop", do_drop, 0);
+    add_primitive("swap", do_swap, 0);
+    add_primitive("over", do_over, 0);
+    add_primitive("rot", do_rot, 0);
+    add_primitive("minus-rot", do_minus_rot, 0);
+    add_primitive("nip", do_nip, 0);
+    add_primitive("tuck", do_tuck, 0);
+
+    // Arithmetic
+    add_primitive("+", do_add, 0);
+    add_primitive("-", do_sub, 0);
+    add_primitive("*", do_mul, 0);
+    add_primitive("/", do_div, 0);
+    add_primitive("mod", do_mod, 0);
+    add_primitive("/mod", do_slash_mod, 0);
+    add_primitive("1+", do_one_plus, 0);
+    add_primitive("1-", do_one_minus, 0);
+    add_primitive("2+", do_two_plus, 0);
+    add_primitive("2-", do_two_minus, 0);
+    add_primitive("negate", do_negate, 0);
+    add_primitive("abs", do_abs, 0);
+    add_primitive("min", do_min, 0);
+    add_primitive("max", do_max, 0);
+
+    // Logic
+    add_primitive("and", do_and, 0);
+    add_primitive("or", do_or, 0);
+    add_primitive("xor", do_xor, 0);
+    add_primitive("invert", do_invert, 0);
+    add_primitive("lshift", do_lshift, 0);
+    add_primitive("rshift", do_rshift, 0);
+
+    // Comparison
+    add_primitive("=", do_eq, 0);
+    add_primitive("<>", do_neq, 0);
+    add_primitive("<", do_lt, 0);
+    add_primitive(">", do_gt, 0);
+    add_primitive("<=", do_lte, 0);
+    add_primitive(">=", do_gte, 0);
+    add_primitive("0=", do_zero_eq, 0);
+    add_primitive("0<", do_zero_lt, 0);
+    add_primitive("0>", do_zero_gt, 0);
+
+    // I/O
+    add_primitive(".", do_dot, 0);
+    add_primitive("cr", do_cr, 0);
+    add_primitive("emit", do_emit, 0);
+    add_primitive("key", do_key, 0);
+    add_primitive(".\"", do_dot_quote, 1 << 7); // Immediate
+    add_primitive("words", do_words, 0);
+
+    // Compilation words
+    add_primitive(":", do_colon, 0);
+    add_primitive(";", do_semicolon, 1 << 7); // Immediate
+
+    // Start outer interpreter
+    outer_interpreter();
+    return 0;
+}