diff options
Diffstat (limited to 'fs/xfs/xfs_bit.c')
| -rw-r--r-- | fs/xfs/xfs_bit.c | 312 |
1 files changed, 312 insertions, 0 deletions
diff --git a/fs/xfs/xfs_bit.c b/fs/xfs/xfs_bit.c new file mode 100644 index 000000000000..a20a6c3dc13e --- /dev/null +++ b/fs/xfs/xfs_bit.c @@ -0,0 +1,312 @@ +/* + * Copyright (c) 2000-2004 Silicon Graphics, Inc. All Rights Reserved. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of version 2 of the GNU General Public License as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it would be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. + * + * Further, this software is distributed without any warranty that it is + * free of the rightful claim of any third person regarding infringement + * or the like. Any license provided herein, whether implied or + * otherwise, applies only to this software file. Patent licenses, if + * any, provided herein do not apply to combinations of this program with + * other software, or any other product whatsoever. + * + * You should have received a copy of the GNU General Public License along + * with this program; if not, write the Free Software Foundation, Inc., 59 + * Temple Place - Suite 330, Boston MA 02111-1307, USA. + * + * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy, + * Mountain View, CA 94043, or: + * + * http://www.sgi.com + * + * For further information regarding this notice, see: + * + * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/ + */ + +/* + * XFS bit manipulation routines, used in non-realtime code. + */ + +#include "xfs.h" +#include "xfs_bit.h" +#include "xfs_log.h" +#include "xfs_trans.h" +#include "xfs_buf_item.h" + + +#ifndef HAVE_ARCH_HIGHBIT +/* + * Index of high bit number in byte, -1 for none set, 0..7 otherwise. + */ +const char xfs_highbit[256] = { + -1, 0, 1, 1, 2, 2, 2, 2, /* 00 .. 07 */ + 3, 3, 3, 3, 3, 3, 3, 3, /* 08 .. 0f */ + 4, 4, 4, 4, 4, 4, 4, 4, /* 10 .. 17 */ + 4, 4, 4, 4, 4, 4, 4, 4, /* 18 .. 1f */ + 5, 5, 5, 5, 5, 5, 5, 5, /* 20 .. 27 */ + 5, 5, 5, 5, 5, 5, 5, 5, /* 28 .. 2f */ + 5, 5, 5, 5, 5, 5, 5, 5, /* 30 .. 37 */ + 5, 5, 5, 5, 5, 5, 5, 5, /* 38 .. 3f */ + 6, 6, 6, 6, 6, 6, 6, 6, /* 40 .. 47 */ + 6, 6, 6, 6, 6, 6, 6, 6, /* 48 .. 4f */ + 6, 6, 6, 6, 6, 6, 6, 6, /* 50 .. 57 */ + 6, 6, 6, 6, 6, 6, 6, 6, /* 58 .. 5f */ + 6, 6, 6, 6, 6, 6, 6, 6, /* 60 .. 67 */ + 6, 6, 6, 6, 6, 6, 6, 6, /* 68 .. 6f */ + 6, 6, 6, 6, 6, 6, 6, 6, /* 70 .. 77 */ + 6, 6, 6, 6, 6, 6, 6, 6, /* 78 .. 7f */ + 7, 7, 7, 7, 7, 7, 7, 7, /* 80 .. 87 */ + 7, 7, 7, 7, 7, 7, 7, 7, /* 88 .. 8f */ + 7, 7, 7, 7, 7, 7, 7, 7, /* 90 .. 97 */ + 7, 7, 7, 7, 7, 7, 7, 7, /* 98 .. 9f */ + 7, 7, 7, 7, 7, 7, 7, 7, /* a0 .. a7 */ + 7, 7, 7, 7, 7, 7, 7, 7, /* a8 .. af */ + 7, 7, 7, 7, 7, 7, 7, 7, /* b0 .. b7 */ + 7, 7, 7, 7, 7, 7, 7, 7, /* b8 .. bf */ + 7, 7, 7, 7, 7, 7, 7, 7, /* c0 .. c7 */ + 7, 7, 7, 7, 7, 7, 7, 7, /* c8 .. cf */ + 7, 7, 7, 7, 7, 7, 7, 7, /* d0 .. d7 */ + 7, 7, 7, 7, 7, 7, 7, 7, /* d8 .. df */ + 7, 7, 7, 7, 7, 7, 7, 7, /* e0 .. e7 */ + 7, 7, 7, 7, 7, 7, 7, 7, /* e8 .. ef */ + 7, 7, 7, 7, 7, 7, 7, 7, /* f0 .. f7 */ + 7, 7, 7, 7, 7, 7, 7, 7, /* f8 .. ff */ +}; +#endif + +/* + * Count of bits set in byte, 0..8. + */ +static const char xfs_countbit[256] = { + 0, 1, 1, 2, 1, 2, 2, 3, /* 00 .. 07 */ + 1, 2, 2, 3, 2, 3, 3, 4, /* 08 .. 0f */ + 1, 2, 2, 3, 2, 3, 3, 4, /* 10 .. 17 */ + 2, 3, 3, 4, 3, 4, 4, 5, /* 18 .. 1f */ + 1, 2, 2, 3, 2, 3, 3, 4, /* 20 .. 27 */ + 2, 3, 3, 4, 3, 4, 4, 5, /* 28 .. 2f */ + 2, 3, 3, 4, 3, 4, 4, 5, /* 30 .. 37 */ + 3, 4, 4, 5, 4, 5, 5, 6, /* 38 .. 3f */ + 1, 2, 2, 3, 2, 3, 3, 4, /* 40 .. 47 */ + 2, 3, 3, 4, 3, 4, 4, 5, /* 48 .. 4f */ + 2, 3, 3, 4, 3, 4, 4, 5, /* 50 .. 57 */ + 3, 4, 4, 5, 4, 5, 5, 6, /* 58 .. 5f */ + 2, 3, 3, 4, 3, 4, 4, 5, /* 60 .. 67 */ + 3, 4, 4, 5, 4, 5, 5, 6, /* 68 .. 6f */ + 3, 4, 4, 5, 4, 5, 5, 6, /* 70 .. 77 */ + 4, 5, 5, 6, 5, 6, 6, 7, /* 78 .. 7f */ + 1, 2, 2, 3, 2, 3, 3, 4, /* 80 .. 87 */ + 2, 3, 3, 4, 3, 4, 4, 5, /* 88 .. 8f */ + 2, 3, 3, 4, 3, 4, 4, 5, /* 90 .. 97 */ + 3, 4, 4, 5, 4, 5, 5, 6, /* 98 .. 9f */ + 2, 3, 3, 4, 3, 4, 4, 5, /* a0 .. a7 */ + 3, 4, 4, 5, 4, 5, 5, 6, /* a8 .. af */ + 3, 4, 4, 5, 4, 5, 5, 6, /* b0 .. b7 */ + 4, 5, 5, 6, 5, 6, 6, 7, /* b8 .. bf */ + 2, 3, 3, 4, 3, 4, 4, 5, /* c0 .. c7 */ + 3, 4, 4, 5, 4, 5, 5, 6, /* c8 .. cf */ + 3, 4, 4, 5, 4, 5, 5, 6, /* d0 .. d7 */ + 4, 5, 5, 6, 5, 6, 6, 7, /* d8 .. df */ + 3, 4, 4, 5, 4, 5, 5, 6, /* e0 .. e7 */ + 4, 5, 5, 6, 5, 6, 6, 7, /* e8 .. ef */ + 4, 5, 5, 6, 5, 6, 6, 7, /* f0 .. f7 */ + 5, 6, 6, 7, 6, 7, 7, 8, /* f8 .. ff */ +}; + +/* + * xfs_highbit32: get high bit set out of 32-bit argument, -1 if none set. + */ +inline int +xfs_highbit32( + __uint32_t v) +{ +#ifdef HAVE_ARCH_HIGHBIT + return highbit32(v); +#else + int i; + + if (v & 0xffff0000) + if (v & 0xff000000) + i = 24; + else + i = 16; + else if (v & 0x0000ffff) + if (v & 0x0000ff00) + i = 8; + else + i = 0; + else + return -1; + return i + xfs_highbit[(v >> i) & 0xff]; +#endif +} + +/* + * xfs_lowbit64: get low bit set out of 64-bit argument, -1 if none set. + */ +int +xfs_lowbit64( + __uint64_t v) +{ + __uint32_t w = (__uint32_t)v; + int n = 0; + + if (w) { /* lower bits */ + n = ffs(w); + } else { /* upper bits */ + w = (__uint32_t)(v >> 32); + if (w && (n = ffs(w))) + n += 32; + } + return n - 1; +} + +/* + * xfs_highbit64: get high bit set out of 64-bit argument, -1 if none set. + */ +int +xfs_highbit64( + __uint64_t v) +{ + __uint32_t h = (__uint32_t)(v >> 32); + + if (h) + return xfs_highbit32(h) + 32; + return xfs_highbit32((__uint32_t)v); +} + + +/* + * Count the number of bits set in the bitmap starting with bit + * start_bit. Size is the size of the bitmap in words. + * + * Do the counting by mapping a byte value to the number of set + * bits for that value using the xfs_countbit array, i.e. + * xfs_countbit[0] == 0, xfs_countbit[1] == 1, xfs_countbit[2] == 1, + * xfs_countbit[3] == 2, etc. + */ +int +xfs_count_bits(uint *map, uint size, uint start_bit) +{ + register int bits; + register unsigned char *bytep; + register unsigned char *end_map; + int byte_bit; + + bits = 0; + end_map = (char*)(map + size); + bytep = (char*)(map + (start_bit & ~0x7)); + byte_bit = start_bit & 0x7; + + /* + * If the caller fell off the end of the map, return 0. + */ + if (bytep >= end_map) { + return (0); + } + + /* + * If start_bit is not byte aligned, then process the + * first byte separately. + */ + if (byte_bit != 0) { + /* + * Shift off the bits we don't want to look at, + * before indexing into xfs_countbit. + */ + bits += xfs_countbit[(*bytep >> byte_bit)]; + bytep++; + } + + /* + * Count the bits in each byte until the end of the bitmap. + */ + while (bytep < end_map) { + bits += xfs_countbit[*bytep]; + bytep++; + } + + return (bits); +} + +/* + * Count the number of contiguous bits set in the bitmap starting with bit + * start_bit. Size is the size of the bitmap in words. + */ +int +xfs_contig_bits(uint *map, uint size, uint start_bit) +{ + uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT); + uint result = 0; + uint tmp; + + size <<= BIT_TO_WORD_SHIFT; + + ASSERT(start_bit < size); + size -= start_bit & ~(NBWORD - 1); + start_bit &= (NBWORD - 1); + if (start_bit) { + tmp = *p++; + /* set to one first offset bits prior to start */ + tmp |= (~0U >> (NBWORD-start_bit)); + if (tmp != ~0U) + goto found; + result += NBWORD; + size -= NBWORD; + } + while (size) { + if ((tmp = *p++) != ~0U) + goto found; + result += NBWORD; + size -= NBWORD; + } + return result - start_bit; +found: + return result + ffz(tmp) - start_bit; +} + +/* + * This takes the bit number to start looking from and + * returns the next set bit from there. It returns -1 + * if there are no more bits set or the start bit is + * beyond the end of the bitmap. + * + * Size is the number of words, not bytes, in the bitmap. + */ +int xfs_next_bit(uint *map, uint size, uint start_bit) +{ + uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT); + uint result = start_bit & ~(NBWORD - 1); + uint tmp; + + size <<= BIT_TO_WORD_SHIFT; + + if (start_bit >= size) + return -1; + size -= result; + start_bit &= (NBWORD - 1); + if (start_bit) { + tmp = *p++; + /* set to zero first offset bits prior to start */ + tmp &= (~0U << start_bit); + if (tmp != 0U) + goto found; + result += NBWORD; + size -= NBWORD; + } + while (size) { + if ((tmp = *p++) != 0U) + goto found; + result += NBWORD; + size -= NBWORD; + } + return -1; +found: + return result + ffs(tmp) - 1; +} |