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/*

 * JFFS2 -- Journalling Flash File System, Version 2.

 *

 * Copyright (C) 2001, 2002 Red Hat, Inc.

 *

 * Created by David Woodhouse <dwmw2@cambridge.redhat.com>

 *

 * For licensing information, see the file 'LICENCE' in this directory.

 *

 * $Id: pushpull.h,v 1.1.1.1 2004-02-14 13:29:20 phoenix Exp $

 *

 */

#ifndef __PUSHPULL_H__

#define __PUSHPULL_H__

#include <linux/errno.h>

struct pushpull {

        unsigned char *buf;

        unsigned int buflen;

        unsigned int ofs;

        unsigned int reserve;

};

static inline void init_pushpull(struct pushpull *pp, char *buf, unsigned buflen, unsigned ofs, unsigned reserve)

{

        pp->buf = buf;

        pp->buflen = buflen;

        pp->ofs = ofs;

        pp->reserve = reserve;

}

static inline int pushbit(struct pushpull *pp, int bit, int use_reserved)

{

        if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve)) {

                return -ENOSPC;

        }

        if (bit) {

                pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs &7)));

        }

        else {

                pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs &7)));

        }

        pp->ofs++;

        return 0;

}

static inline int pushedbits(struct pushpull *pp)

{

        return pp->ofs;

}

static inline int pullbit(struct pushpull *pp)

{

        int bit;

        bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1;

        pp->ofs++;

        return bit;

}

static inline int pulledbits(struct pushpull *pp)

{

        return pp->ofs;

}

#endif /* __PUSHPULL_H__ */