py: Add new cstack API for stack checking, with limit margin macro.

Currently the stack limit margin is hard-coded in each port's call to
`mp_stack_set_limit()`, but on threaded ports it's fiddlier and can lead to
bugs (such as incorrect thread stack margin on esp32).

This commit provides a new API to initialise the C Stack in one function
call, with a config macro to set the margin.  Where possible the new call
is inlined to reduce code size in thread-free ports.

Intended replacement for `MP_TASK_STACK_LIMIT_MARGIN` on esp32.

The previous `stackctrl.h` API is still present and unmodified apart from a
deprecation comment.  However it's not available when the
`MICROPY_PREVIEW_VERSION_2` macro is set.

This work was funded through GitHub Sponsors.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

1 files changed, 2 insertions, 2 deletions

diff --git a/py/objstr.c b/py/objstr.c
index 346a6259f7..757da827c0 100644
--- a/py/objstr.c
+++ b/py/objstr.c
@@ -32,7 +32,7 @@
 #include "py/objstr.h"
 #include "py/objlist.h"
 #include "py/runtime.h"
-#include "py/stackctrl.h"
+#include "py/cstack.h"
 
 #if MICROPY_PY_BUILTINS_STR_OP_MODULO
 static mp_obj_t str_modulo_format(mp_obj_t pattern, size_t n_args, const mp_obj_t *args, mp_obj_t dict);
@@ -1181,7 +1181,7 @@ static vstr_t mp_obj_str_format_helper(const char *str, const char *top, int *ar
             // type        ::=  "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"
 
             // recursively call the formatter to format any nested specifiers
-            MP_STACK_CHECK();
+            mp_cstack_check();
             vstr_t format_spec_vstr = mp_obj_str_format_helper(format_spec, str, arg_i, n_args, args, kwargs);
             const char *s = vstr_null_terminated_str(&format_spec_vstr);
             const char *stop = s + format_spec_vstr.len;