SAVE_OBJECT
};
-/* Special object used to hold a different values for later use. */
+/* Special object used to hold a different values for later use.
+
+ This is mostly used to package C integers and pointers to call
+ record_unwind_protect. Typical task is to pass just one C pointer
+ to unwind function. You should pack pointer with make_save_pointer
+ and then get it back with XSAVE_POINTER, e.g.:
+
+ ...
+ struct my_data *md = get_my_data ();
+ record_unwind_protect (my_unwind, make_save_pointer (md));
+ ...
+
+ Lisp_Object my_unwind (Lisp_Object arg)
+ {
+ struct my_data *md = XSAVE_POINTER (arg, 0);
+ ...
+ }
+
+ If yon need to pass more than just one C pointer, you should
+ use make_save_value. This function allows you to pack up to
+ 4 integers, pointers or Lisp_Objects and conveniently get them
+ back with XSAVE_POINTER, XSAVE_INTEGER and XSAVE_OBJECT macros:
+
+ ...
+ struct my_data *md = get_my_data ();
+ ptrdiff_t my_offset = get_my_offset ();
+ Lisp_Object my_object = get_my_object ();
+ record_unwind_protect
+ (my_unwind, make_save_value ("pio", md, my_offset, my_object));
+ ...
+
+ Lisp_Object my_unwind (Lisp_Object arg)
+ {
+ struct my_data *md = XSAVE_POINTER (arg, 0);
+ ptrdiff_t my_offset = XSAVE_INTEGER (arg, 1);
+ Lisp_Object my_object = XSAVE_OBJECT (arg, 2);
+ ...
+ }
+
+ If ENABLE_CHECKING is in effect, XSAVE_xxx macros do type checking of the
+ saved objects and raise eassert if type of the saved object doesn't match
+ the type which is extracted. In the example above, XSAVE_INTEGER (arg, 2)
+ or XSAVE_OBJECT (arg, 1) are wrong because integer was saved in slot 1 and
+ Lisp_Object was saved in slot 2 of ARG. */
struct Lisp_Save_Value
{
} data[4];
};
-/* Compatibility macro to set and extract saved pointer. */
+/* Macro to set and extract Nth saved pointer. Type
+ checking is ugly because it's used as an lvalue. */
-#define XSAVE_POINTER(obj) XSAVE_VALUE (obj)->data[0].pointer
+#define XSAVE_POINTER(obj, n) \
+ XSAVE_VALUE (obj)->data[(eassert (XSAVE_VALUE (obj)->type \
+ ## n == SAVE_POINTER), n)].pointer
/* Likewise for the saved integer. */
-#define XSAVE_INTEGER(obj) XSAVE_VALUE (obj)->data[1].integer
+#define XSAVE_INTEGER(obj, n) \
+ XSAVE_VALUE (obj)->data[(eassert (XSAVE_VALUE (obj)->type \
+ ## n == SAVE_INTEGER), n)].integer
+
+/* Macro to extract Nth saved object. This is never used as
+ an lvalue, so we can do more convenient type checking. */
+
+#define XSAVE_OBJECT(obj, n) \
+ (eassert (XSAVE_VALUE (obj)->type ## n == SAVE_OBJECT), \
+ XSAVE_VALUE (obj)->data[n].object)
/* A miscellaneous object, when it's on the free list. */
struct Lisp_Free
/* Defined in alloc.c. */
extern void check_pure_size (void);
-extern Lisp_Object allocate_misc (enum Lisp_Misc_Type);
extern void free_misc (Lisp_Object);
extern void allocate_string_data (struct Lisp_String *, EMACS_INT, EMACS_INT);
extern void malloc_warning (const char *);
extern Lisp_Object make_float (double);
extern void display_malloc_warning (void);
extern ptrdiff_t inhibit_garbage_collection (void);
-extern Lisp_Object make_save_value (void *, ptrdiff_t);
-extern void free_save_value (Lisp_Object);
+extern Lisp_Object make_save_value (const char *, ...);
+extern Lisp_Object make_save_pointer (void *);
extern Lisp_Object build_overlay (Lisp_Object, Lisp_Object, Lisp_Object);
extern void free_marker (Lisp_Object);
extern void free_cons (struct Lisp_Cons *);
NITEMS items, each of the same type as *BUF. MULTIPLIER must
positive. The code is tuned for MULTIPLIER being a constant. */
-#define SAFE_NALLOCA(buf, multiplier, nitems) \
- do { \
- if ((nitems) <= MAX_ALLOCA / sizeof *(buf) / (multiplier)) \
- (buf) = alloca (sizeof *(buf) * (multiplier) * (nitems)); \
- else \
+#define SAFE_NALLOCA(buf, multiplier, nitems) \
+ do { \
+ if ((nitems) <= MAX_ALLOCA / sizeof *(buf) / (multiplier)) \
+ (buf) = alloca (sizeof *(buf) * (multiplier) * (nitems)); \
+ else \
{ \
(buf) = xnmalloc (nitems, sizeof *(buf) * (multiplier)); \
sa_must_free = 1; \
record_unwind_protect (safe_alloca_unwind, \
- make_save_value (buf, 0)); \
+ make_save_pointer (buf)); \
} \
} while (0)
{ \
Lisp_Object arg_; \
buf = xmalloc ((nelt) * word_size); \
- arg_ = make_save_value (buf, nelt); \
+ arg_ = make_save_value ("pi", buf, nelt); \
XSAVE_VALUE (arg_)->area = 1; \
sa_must_free = 1; \
record_unwind_protect (safe_alloca_unwind, arg_); \