/* objalloc.h -- routines to allocate memory for objects

Copyright (C) 1997-2015 Free Software Foundation, Inc.

Written by Ian Lance Taylor, Cygnus Solutions.

This program is free software; you can redistribute it and/or modify it

under the terms of the GNU General Public License as published by the

Free Software Foundation; either version 2, or (at your option) any

later version.

This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

GNU General Public License for more details.

You should have received a copy of the GNU General Public License

along with this program; if not, write to the Free Software

Foundation, 51 Franklin Street - Fifth Floor,

Boston, MA 02110-1301, USA. */

#ifndef OBJALLOC_H

#define OBJALLOC_H

#include "ansidecl.h"

/* These routines allocate space for an object. The assumption is

that the object will want to allocate space as it goes along, but

will never want to free any particular block. There is a function

to free a block, which also frees all more recently allocated

blocks. There is also a function to free all the allocated space.

This is essentially a specialization of obstacks. The main

difference is that a block may not be allocated a bit at a time.

Another difference is that these routines are always built on top

of malloc, and always pass an malloc failure back to the caller,

unlike more recent versions of obstacks. */

/* This is what an objalloc structure looks like. Callers should not

refer to these fields, nor should they allocate these structure

themselves. Instead, they should only create them via

objalloc_init, and only access them via the functions and macros

listed below. The structure is only defined here so that we can

access it via macros. */

struct objalloc

{

char *current_ptr;

unsigned int current_space;

void *chunks;

};

/* Work out the required alignment. */

struct objalloc_align { char x; double d; };

#if defined (__STDC__) && __STDC__

#ifndef offsetof

#include <stddef.h>

#endif

#endif

#ifndef offsetof

#define offsetof(TYPE, MEMBER) ((unsigned long) &((TYPE *)0)->MEMBER)

#endif

#define OBJALLOC_ALIGN offsetof (struct objalloc_align, d)

/* Create an objalloc structure. Returns NULL if malloc fails. */

extern struct objalloc *objalloc_create (void);

/* Allocate space from an objalloc structure. Returns NULL if malloc

fails. */

extern void *_objalloc_alloc (struct objalloc *, unsigned long);

/* The macro version of objalloc_alloc. We only define this if using

gcc, because otherwise we would have to evaluate the arguments

multiple times, or use a temporary field as obstack.h does. */

#if defined (__GNUC__) && defined (__STDC__) && __STDC__

/* NextStep 2.0 cc is really gcc 1.93 but it defines __GNUC__ = 2 and

does not implement __extension__. But that compiler doesn't define

__GNUC_MINOR__. */

#if __GNUC__ < 2 || (__NeXT__ && !__GNUC_MINOR__)

#define __extension__

#endif

#define objalloc_alloc(o, l) \

__extension__ \

({ struct objalloc *__o = (o); \

unsigned long __len = (l); \

if (__len == 0) \

__len = 1; \

__len = (__len + OBJALLOC_ALIGN - 1) &~ (OBJALLOC_ALIGN - 1); \

(__len != 0 && __len <= __o->current_space \

? (__o->current_ptr += __len, \

__o->current_space -= __len, \

(void *) (__o->current_ptr - __len)) \

: _objalloc_alloc (__o, __len)); })

#else /* ! __GNUC__ */

#define objalloc_alloc(o, l) _objalloc_alloc ((o), (l))

#endif /* ! __GNUC__ */

/* Free an entire objalloc structure. */

extern void objalloc_free (struct objalloc *);

/* Free a block allocated by objalloc_alloc. This also frees all more

recently allocated blocks. */

extern void objalloc_free_block (struct objalloc *, void *);

#endif /* OBJALLOC_H */