gdb/include/obstack.h

68 The way we do this is to take a large chunk, allocating memory from
69 low addresses.  When you want to build a symbol in the chunk you just
70 add chars above the current "high water mark" in the chunk.  When you
73 Mostly the chars will not burst over the highest address of the chunk,
74 because you would typically expect a chunk to be (say) 100 times as
84 When the chars burst over a chunk boundary, we allocate a larger
85 chunk, and then copy the partly formed object from the end of the old
86 chunk to the beginning of the new larger chunk.  We then carry on
95 	We carve out one object at a time from the current chunk.
162 struct _obstack_chunk		/* Lives at front of each chunk. */
164   char  *limit;			/* 1 past end of this chunk */
165   struct _obstack_chunk *prev;	/* address of prior chunk or NULL */
169 struct obstack		/* control current object in current chunk */
172   struct _obstack_chunk *chunk;	/* address of current struct obstack_chunk */
175   char	*chunk_limit;		/* address of char after current chunk */
184   void *extra_arg;		/* first arg for chunk alloc/dealloc funcs */
186   struct _obstack_chunk *(*chunkfun) (); /* User's fcn to allocate a chunk.  */
187   void (*freefun) ();		/* User's function to free a chunk.  */
188   char *extra_arg;		/* first arg for chunk alloc/dealloc funcs */
190   unsigned use_extra_arg:1;	/* chunk alloc/dealloc funcs take extra arg */
192 				   chunk contains a zero-length object.  This
193 				   prevents freeing the chunk if we allocate
194 				   a bigger chunk to replace it. */
280    because a new chunk might be needed to hold the final size.  */
288 /* Pointer to next byte not yet allocated in current chunk.  */
390      (__o->chunk->prev == 0 && __o->next_free - __o->chunk->contents == 0); })
492    if (__o1->next_free - (char *)__o1->chunk				\
493        > __o1->chunk_limit - (char *)__o1->chunk)			\
502    if (__obj > (void *)__o->chunk && __obj < (void *)__o->chunk_limit)  \
516  ((h)->chunk->prev == 0 && (h)->next_free - (h)->chunk->contents == 0)
588   (((h)->next_free - (char *) (h)->chunk				\
589     > (h)->chunk_limit - (char *) (h)->chunk)				\
596 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk,			\
597   (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
599 	    = (h)->temp + (char *) (h)->chunk)				\
600    : (((obstack_free) ((h), (h)->temp + (char *) (h)->chunk), 0), 0)))
603 ( (h)->temp = (char *) (obj) - (char *) (h)->chunk,			\
604   (((h)->temp > 0 && (h)->temp < (h)->chunk_limit - (char *) (h)->chunk)\
606 	    = (h)->temp + (char *) (h)->chunk)				\
607    : (_obstack_free ((h), (h)->temp + (char *) (h)->chunk), 0)))