1 /* 2 * JFFS2 -- Journalling Flash File System, Version 2. 3 * 4 * Copyright (C) 2001, 2002 Red Hat, Inc. 5 * 6 * Created by David Woodhouse <[email protected]> 7 * 8 * For licensing information, see the file 'LICENCE' in this directory. 9 * 10 * $Id: pushpull.h,v 1.10 2004/11/16 20:36:11 dwmw2 Exp $ 11 * 12 */ 13 14 #ifndef __PUSHPULL_H__ 15 #define __PUSHPULL_H__ 16 17 #include <linux/errno.h> 18 19 struct pushpull { 20 unsigned char *buf; 21 unsigned int buflen; 22 unsigned int ofs; 23 unsigned int reserve; 24 }; 25 26 27 static inline void init_pushpull(struct pushpull *pp, char *buf, unsigned buflen, unsigned ofs, unsigned reserve) 28 { 29 pp->buf = (unsigned char *)buf; 30 pp->buflen = buflen; 31 pp->ofs = ofs; 32 pp->reserve = reserve; 33 } 34 35 static inline int pushbit(struct pushpull *pp, int bit, int use_reserved) 36 { 37 if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve)) { 38 return -ENOSPC; 39 } 40 41 if (bit) { 42 pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs &7))); 43 } 44 else { 45 pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs &7))); 46 } 47 pp->ofs++; 48 49 return 0; 50 } 51 52 static inline int pushedbits(struct pushpull *pp) 53 { 54 return pp->ofs; 55 } 56 57 static inline int pullbit(struct pushpull *pp) 58 { 59 int bit; 60 61 bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1; 62 63 pp->ofs++; 64 return bit; 65 } 66 67 static inline int pulledbits(struct pushpull *pp) 68 { 69 return pp->ofs; 70 } 71 72 #endif /* __PUSHPULL_H__ */ 73