| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * JFFS2 -- Journalling Flash File System, Version 2. |
| 3 | * |
| 4 | * Copyright (C) 2001, 2002 Red Hat, Inc. |
| 5 | * |
| 6 | * Created by David Woodhouse <dwmw2@infradead.org> |
| 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 = 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__ */ |