[thirdparty/xfsprogs-dev.git] / libxfs / xfs_bit.c

/*
 * Copyright (c) 2000-2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms 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.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "libxfs_priv.h"
#include "xfs_log_format.h"
#include "xfs_bit.h"

/*
 * XFS bit manipulation routines, used in non-realtime code.
 */

/*
 * Return whether bitmap is empty.
 * Size is number of words in the bitmap, which is padded to word boundary
 * Returns 1 for empty, 0 for non-empty.
 */
int
xfs_bitmap_empty(uint *map, uint size)
{
	uint i;
	uint ret = 0;

	for (i = 0; i < size; i++) {
		ret |= map[i];
	}

	return (ret == 0);
}

/*
 * 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;
}
Commit	Line	Data
4071f725 DC	1	/*
	2	* Copyright (c) 2000-2005 Silicon Graphics, Inc.
	3	* All Rights Reserved.
	4	*
	5	* This program is free software; you can redistribute it and/or
	6	* modify it under the terms of the GNU General Public License as
	7	* published by the Free Software Foundation.
	8	*
	9	* This program is distributed in the hope that it would be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; if not, write the Free Software Foundation,
	16	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	17	*/
	18	#include "libxfs_priv.h"
	19	#include "xfs_log_format.h"
	20	#include "xfs_bit.h"
	21
	22	/*
	23	* XFS bit manipulation routines, used in non-realtime code.
	24	*/
	25
	26	/*
	27	* Return whether bitmap is empty.
	28	* Size is number of words in the bitmap, which is padded to word boundary
	29	* Returns 1 for empty, 0 for non-empty.
	30	*/
	31	int
	32	xfs_bitmap_empty(uint *map, uint size)
	33	{
	34	uint i;
	35	uint ret = 0;
	36
	37	for (i = 0; i < size; i++) {
	38	ret \|= map[i];
	39	}
	40
	41	return (ret == 0);
	42	}
	43
	44	/*
	45	* Count the number of contiguous bits set in the bitmap starting with bit
	46	* start_bit. Size is the size of the bitmap in words.
	47	*/
	48	int
	49	xfs_contig_bits(uint *map, uint size, uint start_bit)
	50	{
	51	uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
	52	uint result = 0;
	53	uint tmp;
	54
	55	size <<= BIT_TO_WORD_SHIFT;
	56
	57	ASSERT(start_bit < size);
	58	size -= start_bit & ~(NBWORD - 1);
	59	start_bit &= (NBWORD - 1);
	60	if (start_bit) {
	61	tmp = *p++;
	62	/* set to one first offset bits prior to start */
	63	tmp \|= (~0U >> (NBWORD-start_bit));
	64	if (tmp != ~0U)
65	goto found;
66	result += NBWORD;
67	size -= NBWORD;
68	}
69	while (size) {
70	if ((tmp = *p++) != ~0U)
71	goto found;
72	result += NBWORD;
73	size -= NBWORD;
74	}
75	return result - start_bit;
76	found:
77	return result + ffz(tmp) - start_bit;
78	}
79
80	/*
81	* This takes the bit number to start looking from and
82	* returns the next set bit from there. It returns -1
83	* if there are no more bits set or the start bit is
84	* beyond the end of the bitmap.
85	*
86	* Size is the number of words, not bytes, in the bitmap.
87	*/
88	int xfs_next_bit(uint *map, uint size, uint start_bit)
89	{
90	uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
91	uint result = start_bit & ~(NBWORD - 1);
92	uint tmp;
93
94	size <<= BIT_TO_WORD_SHIFT;
95
96	if (start_bit >= size)
97	return -1;
98	size -= result;
99	start_bit &= (NBWORD - 1);
100	if (start_bit) {
101	tmp = *p++;
102	/* set to zero first offset bits prior to start */
103	tmp &= (~0U << start_bit);
104	if (tmp != 0U)
105	goto found;
106	result += NBWORD;
107	size -= NBWORD;
108	}
109	while (size) {
110	if ((tmp = *p++) != 0U)
111	goto found;
112	result += NBWORD;
113	size -= NBWORD;
114	}
115	return -1;
116	found:
117	return result + ffs(tmp) - 1;
118	}