[linux.git] / fs / xfs / 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 "xfs.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_trans.h"
#include "xfs_buf_item.h"

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

#ifndef HAVE_ARCH_HIGHBIT
/*
 * Index of high bit number in byte, -1 for none set, 0..7 otherwise.
 */
STATIC 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;
}
Commit	Line	Data
1da177e4	1	/*
7b718769 NS	2	* Copyright (c) 2000-2005 Silicon Graphics, Inc.
7b718769 NS	3	* All Rights Reserved.
1da177e4	4	*
7b718769 NS	5	* This program is free software; you can redistribute it and/or
7b718769 NS	6	* modify it under the terms of the GNU General Public License as
1da177e4 LT	7	* published by the Free Software Foundation.
1da177e4 LT	8	*
7b718769 NS	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.
1da177e4	13	*
7b718769 NS	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
1da177e4	17	*/
1da177e4 LT	18	#include "xfs.h"
	19	#include "xfs_bit.h"
	20	#include "xfs_log.h"
	21	#include "xfs_trans.h"
	22	#include "xfs_buf_item.h"
	23
7b718769 NS	24	/*
	25	* XFS bit manipulation routines, used in non-realtime code.
	26	*/
1da177e4 LT	27
	28	#ifndef HAVE_ARCH_HIGHBIT
	29	/*
	30	* Index of high bit number in byte, -1 for none set, 0..7 otherwise.
	31	*/
ba0f32d4	32	STATIC const char xfs_highbit[256] = {
1da177e4 LT	33	-1, 0, 1, 1, 2, 2, 2, 2, /* 00 .. 07 */
	34	3, 3, 3, 3, 3, 3, 3, 3, /* 08 .. 0f */
	35	4, 4, 4, 4, 4, 4, 4, 4, /* 10 .. 17 */
	36	4, 4, 4, 4, 4, 4, 4, 4, /* 18 .. 1f */
	37	5, 5, 5, 5, 5, 5, 5, 5, /* 20 .. 27 */
	38	5, 5, 5, 5, 5, 5, 5, 5, /* 28 .. 2f */
	39	5, 5, 5, 5, 5, 5, 5, 5, /* 30 .. 37 */
	40	5, 5, 5, 5, 5, 5, 5, 5, /* 38 .. 3f */
	41	6, 6, 6, 6, 6, 6, 6, 6, /* 40 .. 47 */
	42	6, 6, 6, 6, 6, 6, 6, 6, /* 48 .. 4f */
	43	6, 6, 6, 6, 6, 6, 6, 6, /* 50 .. 57 */
	44	6, 6, 6, 6, 6, 6, 6, 6, /* 58 .. 5f */
	45	6, 6, 6, 6, 6, 6, 6, 6, /* 60 .. 67 */
	46	6, 6, 6, 6, 6, 6, 6, 6, /* 68 .. 6f */
	47	6, 6, 6, 6, 6, 6, 6, 6, /* 70 .. 77 */
	48	6, 6, 6, 6, 6, 6, 6, 6, /* 78 .. 7f */
	49	7, 7, 7, 7, 7, 7, 7, 7, /* 80 .. 87 */
	50	7, 7, 7, 7, 7, 7, 7, 7, /* 88 .. 8f */
	51	7, 7, 7, 7, 7, 7, 7, 7, /* 90 .. 97 */
	52	7, 7, 7, 7, 7, 7, 7, 7, /* 98 .. 9f */
	53	7, 7, 7, 7, 7, 7, 7, 7, /* a0 .. a7 */
	54	7, 7, 7, 7, 7, 7, 7, 7, /* a8 .. af */
	55	7, 7, 7, 7, 7, 7, 7, 7, /* b0 .. b7 */
	56	7, 7, 7, 7, 7, 7, 7, 7, /* b8 .. bf */
	57	7, 7, 7, 7, 7, 7, 7, 7, /* c0 .. c7 */
	58	7, 7, 7, 7, 7, 7, 7, 7, /* c8 .. cf */
	59	7, 7, 7, 7, 7, 7, 7, 7, /* d0 .. d7 */
	60	7, 7, 7, 7, 7, 7, 7, 7, /* d8 .. df */
	61	7, 7, 7, 7, 7, 7, 7, 7, /* e0 .. e7 */
	62	7, 7, 7, 7, 7, 7, 7, 7, /* e8 .. ef */
	63	7, 7, 7, 7, 7, 7, 7, 7, /* f0 .. f7 */
	64	7, 7, 7, 7, 7, 7, 7, 7, /* f8 .. ff */
	65	};
	66	#endif
	67
	68	/*
	69	* Count of bits set in byte, 0..8.
	70	*/
	71	static const char xfs_countbit[256] = {
	72	0, 1, 1, 2, 1, 2, 2, 3, /* 00 .. 07 */
	73	1, 2, 2, 3, 2, 3, 3, 4, /* 08 .. 0f */
	74	1, 2, 2, 3, 2, 3, 3, 4, /* 10 .. 17 */
	75	2, 3, 3, 4, 3, 4, 4, 5, /* 18 .. 1f */
	76	1, 2, 2, 3, 2, 3, 3, 4, /* 20 .. 27 */
	77	2, 3, 3, 4, 3, 4, 4, 5, /* 28 .. 2f */
	78	2, 3, 3, 4, 3, 4, 4, 5, /* 30 .. 37 */
	79	3, 4, 4, 5, 4, 5, 5, 6, /* 38 .. 3f */
	80	1, 2, 2, 3, 2, 3, 3, 4, /* 40 .. 47 */
	81	2, 3, 3, 4, 3, 4, 4, 5, /* 48 .. 4f */
	82	2, 3, 3, 4, 3, 4, 4, 5, /* 50 .. 57 */
	83	3, 4, 4, 5, 4, 5, 5, 6, /* 58 .. 5f */
	84	2, 3, 3, 4, 3, 4, 4, 5, /* 60 .. 67 */
	85	3, 4, 4, 5, 4, 5, 5, 6, /* 68 .. 6f */
	86	3, 4, 4, 5, 4, 5, 5, 6, /* 70 .. 77 */
	87	4, 5, 5, 6, 5, 6, 6, 7, /* 78 .. 7f */
	88	1, 2, 2, 3, 2, 3, 3, 4, /* 80 .. 87 */
	89	2, 3, 3, 4, 3, 4, 4, 5, /* 88 .. 8f */
	90	2, 3, 3, 4, 3, 4, 4, 5, /* 90 .. 97 */
	91	3, 4, 4, 5, 4, 5, 5, 6, /* 98 .. 9f */
	92	2, 3, 3, 4, 3, 4, 4, 5, /* a0 .. a7 */
	93	3, 4, 4, 5, 4, 5, 5, 6, /* a8 .. af */
	94	3, 4, 4, 5, 4, 5, 5, 6, /* b0 .. b7 */
	95	4, 5, 5, 6, 5, 6, 6, 7, /* b8 .. bf */
	96	2, 3, 3, 4, 3, 4, 4, 5, /* c0 .. c7 */
97	3, 4, 4, 5, 4, 5, 5, 6, /* c8 .. cf */
98	3, 4, 4, 5, 4, 5, 5, 6, /* d0 .. d7 */
99	4, 5, 5, 6, 5, 6, 6, 7, /* d8 .. df */
100	3, 4, 4, 5, 4, 5, 5, 6, /* e0 .. e7 */
101	4, 5, 5, 6, 5, 6, 6, 7, /* e8 .. ef */
102	4, 5, 5, 6, 5, 6, 6, 7, /* f0 .. f7 */
103	5, 6, 6, 7, 6, 7, 7, 8, /* f8 .. ff */
104	};
105
106	/*
107	* xfs_highbit32: get high bit set out of 32-bit argument, -1 if none set.
108	*/
109	inline int
110	xfs_highbit32(
111	__uint32_t v)
112	{
113	#ifdef HAVE_ARCH_HIGHBIT
114	return highbit32(v);
115	#else
116	int i;
117
118	if (v & 0xffff0000)
119	if (v & 0xff000000)
120	i = 24;
121	else
122	i = 16;
123	else if (v & 0x0000ffff)
124	if (v & 0x0000ff00)
125	i = 8;
126	else
127	i = 0;
128	else
129	return -1;
130	return i + xfs_highbit[(v >> i) & 0xff];
131	#endif
132	}
133
134	/*
135	* xfs_lowbit64: get low bit set out of 64-bit argument, -1 if none set.
136	*/
137	int
138	xfs_lowbit64(
139	__uint64_t v)
140	{
141	__uint32_t w = (__uint32_t)v;
142	int n = 0;
143
144	if (w) { /* lower bits */
145	n = ffs(w);
146	} else { /* upper bits */
147	w = (__uint32_t)(v >> 32);
148	if (w && (n = ffs(w)))
149	n += 32;
150	}
151	return n - 1;
152	}
153
154	/*
155	* xfs_highbit64: get high bit set out of 64-bit argument, -1 if none set.
156	*/
157	int
158	xfs_highbit64(
159	__uint64_t v)
160	{
161	__uint32_t h = (__uint32_t)(v >> 32);
162
163	if (h)
164	return xfs_highbit32(h) + 32;
165	return xfs_highbit32((__uint32_t)v);
166	}
167
168
169	/*
170	* Count the number of bits set in the bitmap starting with bit
171	* start_bit. Size is the size of the bitmap in words.
172	*
173	* Do the counting by mapping a byte value to the number of set
174	* bits for that value using the xfs_countbit array, i.e.
175	* xfs_countbit[0] == 0, xfs_countbit[1] == 1, xfs_countbit[2] == 1,
176	* xfs_countbit[3] == 2, etc.
177	*/
178	int
179	xfs_count_bits(uint *map, uint size, uint start_bit)
180	{
181	register int bits;
182	register unsigned char *bytep;
183	register unsigned char *end_map;
184	int byte_bit;
185
186	bits = 0;
187	end_map = (char*)(map + size);
188	bytep = (char*)(map + (start_bit & ~0x7));
189	byte_bit = start_bit & 0x7;
190
191	/*
192	* If the caller fell off the end of the map, return 0.
193	*/
194	if (bytep >= end_map) {
195	return (0);
196	}
197
198	/*
199	* If start_bit is not byte aligned, then process the
200	* first byte separately.
201	*/
202	if (byte_bit != 0) {
203	/*
204	* Shift off the bits we don't want to look at,
205	* before indexing into xfs_countbit.
206	*/
207	bits += xfs_countbit[(*bytep >> byte_bit)];
208	bytep++;
209	}
210
211	/*
212	* Count the bits in each byte until the end of the bitmap.
213	*/
214	while (bytep < end_map) {
215	bits += xfs_countbit[*bytep];
216	bytep++;
217	}
218
219	return (bits);
220	}
221
222	/*
223	* Count the number of contiguous bits set in the bitmap starting with bit
224	* start_bit. Size is the size of the bitmap in words.
225	*/
226	int
227	xfs_contig_bits(uint *map, uint size, uint start_bit)
228	{
229	uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
230	uint result = 0;
231	uint tmp;
232
233	size <<= BIT_TO_WORD_SHIFT;
234
235	ASSERT(start_bit < size);
236	size -= start_bit & ~(NBWORD - 1);
237	start_bit &= (NBWORD - 1);
238	if (start_bit) {
239	tmp = *p++;
240	/* set to one first offset bits prior to start */
241	tmp \|= (~0U >> (NBWORD-start_bit));
242	if (tmp != ~0U)
243	goto found;
244	result += NBWORD;
245	size -= NBWORD;
246	}
247	while (size) {
248	if ((tmp = *p++) != ~0U)
249	goto found;
250	result += NBWORD;
251	size -= NBWORD;
252	}
253	return result - start_bit;
254	found:
255	return result + ffz(tmp) - start_bit;
256	}
257
258	/*
259	* This takes the bit number to start looking from and
260	* returns the next set bit from there. It returns -1
261	* if there are no more bits set or the start bit is
262	* beyond the end of the bitmap.
263	*
264	* Size is the number of words, not bytes, in the bitmap.
265	*/
266	int xfs_next_bit(uint *map, uint size, uint start_bit)
267	{
268	uint * p = ((unsigned int *) map) + (start_bit >> BIT_TO_WORD_SHIFT);
269	uint result = start_bit & ~(NBWORD - 1);
270	uint tmp;
271
272	size <<= BIT_TO_WORD_SHIFT;
273
274	if (start_bit >= size)
275	return -1;
276	size -= result;
277	start_bit &= (NBWORD - 1);
278	if (start_bit) {
279	tmp = *p++;
280	/* set to zero first offset bits prior to start */
281	tmp &= (~0U << start_bit);
282	if (tmp != 0U)
283	goto found;
284	result += NBWORD;
285	size -= NBWORD;
286	}
287	while (size) {
288	if ((tmp = *p++) != 0U)
289	goto found;
290	result += NBWORD;
291	size -= NBWORD;
292	}
293	return -1;
294	found:
295	return result + ffs(tmp) - 1;
296	}