feat: add comma, fix allot, and support bare-metal custom memory

Co-authored-by: aider (openrouter/moonshotai/kimi-k2.6) <aider@aider.chat>

forth.h

@@ -196,6 +196,7 @@ void do_do_var(Word* w);
 void do_do_const(Word* w);
 void do_here(Word* w);
 void do_allot(Word* w);
+void do_comma(Word* w);
 
 // Return stack
 void do_to_r(Word* w);

forth_core.c

@@ -1,13 +1,21 @@
 #include "forth.h"
 
 // Static storage for bare-metal portability
+#ifndef FORTH_CUSTOM_MEMORY
 static int64_t data_stack_storage[FORTH_DATA_STACK_SIZE];
 int64_t *data_stack = data_stack_storage;
+#else
+int64_t *data_stack;
+#endif
 int32_t data_sp = -1;
 int32_t data_cap = FORTH_DATA_STACK_SIZE;
 
+#ifndef FORTH_CUSTOM_MEMORY
 static Cell ret_stack_storage[FORTH_RET_STACK_SIZE];
 Cell *ret_stack = ret_stack_storage;
+#else
+Cell *ret_stack;
+#endif
 int32_t rp = -1;
 int32_t ret_cap = FORTH_RET_STACK_SIZE;
 Cell* ip = NULL;
@@ -16,8 +24,12 @@ Word* dict_head = NULL;
 
 int state = 0;
 
+#ifndef FORTH_CUSTOM_MEMORY
 static Cell compile_buf_storage[FORTH_COMPILE_BUF_SIZE];
 Cell *compile_buf = compile_buf_storage;
+#else
+Cell *compile_buf;
+#endif
 int32_t compile_idx = 0;
 int32_t compile_cap = FORTH_COMPILE_BUF_SIZE;
 char compiling_name[MAX_NAME_LEN + 1] = {0};
@@ -26,15 +38,24 @@ char* input_buf = NULL;
 size_t input_buf_cap = 0;
 char* input_ptr = NULL;
 
+#ifndef FORTH_CUSTOM_MEMORY
 static int64_t compile_stack_storage[FORTH_COMPILE_STACK_SIZE];
 int64_t *compile_stack = compile_stack_storage;
+#else
+int64_t *compile_stack;
+#endif
 int32_t compile_sp = -1;
 int32_t compile_stack_cap = FORTH_COMPILE_STACK_SIZE;
 
+#ifndef FORTH_CUSTOM_MEMORY
 static Cell user_mem_storage[FORTH_USER_MEM_CELLS];
 Cell *user_mem = user_mem_storage;
-int64_t user_mem_size = FORTH_USER_MEM_CELLS;
 Cell* here = user_mem_storage;
+#else
+Cell *user_mem;
+Cell* here;
+#endif
+int64_t user_mem_size = FORTH_USER_MEM_CELLS;
 
 Word* w_exit = NULL;
 Word* w_docolon = NULL;

forth_words.c

@@ -456,13 +456,25 @@ void do_here(Word* w) {
 void do_allot(Word* w) {
     (void)w;
     int64_t n = data_pop();
-    if (here + n > user_mem + user_mem_size) {
-        forth_printf("User memory overflow\n");
+    int64_t idx = here - user_mem;
+    if (idx + n < 0 || idx + n > user_mem_size) {
+        forth_printf("User memory out of bounds\n");
         return;
     }
     here += n;
 }
 
+void do_comma(Word* w) {
+    (void)w;
+    int64_t val = data_pop();
+    if (here + 1 > user_mem + user_mem_size) {
+        forth_printf("User memory overflow\n");
+        return;
+    }
+    here->num = val;
+    here++;
+}
+
 // Variable and constant
 void do_variable(Word* w) {
     (void)w;

main.c

@@ -75,6 +75,7 @@ int main(void) {
     add_primitive("constant", do_constant, 0);
     add_primitive("here",  do_here, 0);
     add_primitive("allot", do_allot, 0);
+    add_primitive(",",     do_comma, 0);
 
     // Return stack
     add_primitive(">r", do_to_r, 0);