patch-2.4.25 linux-2.4.25/fs/xfs/xfs_bit.c

• Lines: 313
• Date: 2004-02-18 05:36:32.000000000 -0800
• Orig file: linux-2.4.24/fs/xfs/xfs_bit.c
• Orig date: 1969-12-31 16:00:00.000000000 -0800

diff -urN linux-2.4.24/fs/xfs/xfs_bit.c linux-2.4.25/fs/xfs/xfs_bit.c
@@ -0,0 +1,312 @@
+/*
+ * Copyright (c) 2000-2002 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)
+{
+	int n;
+	n = ffs((unsigned)v);
+	if (n <= 0) {
+		n = ffs(v >> 32);
+		if (n >= 0)
+			n+=32;
+	}
+	return (n <= 0) ? n : 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 = v >> 32;
+	if (h)
+		return xfs_highbit32(h) + 32;
+	return xfs_highbit32((__u32)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)
+{
+#if BITS_PER_LONG == 32
+	return find_next_zero_bit((unsigned long *)map,
+			size * sizeof(uint) * 8, start_bit) - start_bit;
+#else
+	/*
+	 * The first argument to find_next_zero_bit needs to be aligned,
+	 * but this is coming from the xfs_buf_log_format_t on-disk
+	 * struct, which can't be padded or otherwise modified w/o breaking
+	 * on-disk compatibility... so create a temporary, aligned
+	 * variable, copy over the bitmap, and send that to find_next_zero_bit
+	 * This only happens in recovery, so it's ugly but not too bad.
+	 */
+	void * addr;
+	int bit;
+	size_t bitmap_size = size * sizeof(uint);
+
+	addr = (void *)kmem_alloc(bitmap_size, KM_SLEEP);
+	memcpy(addr, map, size * sizeof(uint));
+
+	bit = find_next_zero_bit((unsigned long *)addr,
+			size * sizeof(uint) * 8, start_bit) - start_bit;
+
+	kmem_free(addr, bitmap_size);
+
+	return bit;
+#endif
+}
+
+/*
+ * 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 */
+		tmp &= (~0U << start_bit);
+		if (size < NBWORD)
+			goto found_first;
+		if (tmp != 0U)
+			goto found_middle;
+		size -= NBWORD;
+		result += NBWORD;
+	}
+	while (size >= NBWORD) {
+		if ((tmp = *p++) != 0U)
+			goto found_middle;
+		result += NBWORD;
+		size -= NBWORD;
+	}
+	if (!size)
+		return -1;
+	tmp = *p;
+found_first:
+found_middle:
+	return result + ffs(tmp) - 1;
+}