1/* 2 * macros to convert each packed bitfield structure from little endian to big 3 * endian and vice versa. These are needed when creating a filesystem on a 4 * machine with different byte ordering to the target architecture. 5 * 6 * Copyright (c) 2002, 2003, 2004 Phillip Lougher <plougher@users.sourceforge.net> 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU General Public License 10 * as published by the Free Software Foundation; either version 2, 11 * or (at your option) any later version. 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU General Public License for more details. 17 * 18 * You should have received a copy of the GNU General Public License 19 * along with this program; if not, write to the Free Software 20 * Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 21 * 22 * mksquashfs.h 23 * 24 */ 25 26/* 27 * macros used to swap each structure entry, taking into account 28 * bitfields and different bitfield placing conventions on differing architectures 29 */ 30#if __BYTE_ORDER == __BIG_ENDIAN 31 /* convert from big endian to little endian */ 32#define SQUASHFS_SWAP(value, p, pos, tbits) _SQUASHFS_SWAP(value, p, pos, tbits, b_pos) 33#else 34 /* convert from little endian to big endian */ 35#define SQUASHFS_SWAP(value, p, pos, tbits) _SQUASHFS_SWAP(value, p, pos, tbits, 64 - tbits - b_pos) 36#endif 37 38#define _SQUASHFS_SWAP(value, p, pos, tbits, SHIFT) {\ 39 int bits;\ 40 int b_pos = pos % 8;\ 41 unsigned long long val = (long long) value << (SHIFT);\ 42 unsigned char *s = ((unsigned char *) &val) + 7;\ 43 unsigned char *d = ((unsigned char *)p) + (pos / 8);\ 44 for(bits = 0; bits < (tbits + b_pos); bits += 8) \ 45 *d++ |= *s--;\ 46} 47#define SQUASHFS_MEMSET(s, d, n) memset(d, 0, n); 48