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