[mirror_frr.git] / lib / bitfield.h

/* Bitfields
 * Copyright (C) 2016 Cumulus Networks, Inc.
 *
 * This file is part of Quagga.
 *
 * Quagga 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; either version 2, or (at your option) any
 * later version.
 *
 * Quagga is distributed in the hope that it will 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; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */
/**
 * A simple bit array implementation to allocate and free IDs. An example
 * of its usage is in allocating link state IDs for OSPFv3 as OSPFv3 has
 * removed all address semantics from LS ID. Another usage can be in
 * allocating IDs for BGP neighbors (and dynamic update groups) for
 * efficient storage of adj-rib-out.
 *
 * An example:
 * #include "bitfield.h"
 *
 * bitfield_t bitfield;
 *
 * bf_init(bitfield, 32);
 * ...
 * bf_assign_index(bitfield, id1);
 * bf_assign_index(bitfield, id2);
 * ...
 * bf_release_index(bitfield, id1);
 */

#ifndef _BITFIELD_H
#define _BITFIELD_H

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#ifdef __cplusplus
extern "C" {
#endif

typedef unsigned int word_t;
#define WORD_MAX 0xFFFFFFFF
#define WORD_SIZE (sizeof(word_t) * 8)

/**
 * The bitfield structure.
 * @data: the bits to manage.
 * @n: The current word number that is being used.
 * @m: total number of words in 'data'
 */
typedef struct {word_t *data; size_t n, m; } bitfield_t;

DECLARE_MTYPE(BITFIELD);

/**
 * Initialize the bits.
 * @v: an instance of bitfield_t struct.
 * @N: number of bits to start with, which equates to how many
 *     IDs can be allocated.
 */
#define bf_init(v, N)                                                          \
	do {                                                                   \
		(v).n = 0;                                                     \
		(v).m = ((N) / WORD_SIZE + 1);                                 \
		(v).data = XCALLOC(MTYPE_BITFIELD, ((v).m * sizeof(word_t)));  \
	} while (0)

/**
 * allocate and assign an id from bitfield v.
 */
#define bf_assign_index(v, id)                                                 \
	do {                                                                   \
		bf_find_bit(v, id);                                            \
		bf_set_bit(v, id);                                             \
	} while (0)

/*
 * allocate and assign 0th bit in the bitfiled.
 */
#define bf_assign_zero_index(v)                                                \
	do {                                                                   \
		int id = 0;                                                    \
		bf_assign_index(v, id);                                        \
	} while (0)

/*
 * return an id to bitfield v
 */
#define bf_release_index(v, id)                                                \
	(v).data[bf_index(id)] &= ~(1 << (bf_offset(id)))

/* check if an id is in use */
#define bf_test_index(v, id)                                                \
	((v).data[bf_index(id)] & (1 << (bf_offset(id))))

/* check if the bit field has been setup */
#define bf_is_inited(v) ((v).data)

/* compare two bitmaps of the same length */
#define bf_cmp(v1, v2) (memcmp((v1).data, (v2).data, ((v1).m * sizeof(word_t))))

/*
 * return 0th index back to bitfield
 */
#define bf_release_zero_index(v) bf_release_index(v, 0)

#define bf_index(b) ((b) / WORD_SIZE)
#define bf_offset(b) ((b) % WORD_SIZE)

/**
 * Set a bit in the array. If it fills up that word and we are
 * out of words, extend it by one more word.
 */
#define bf_set_bit(v, b)                                                       \
	do {                                                                   \
		size_t w = bf_index(b);                                        \
		(v).data[w] |= 1 << (bf_offset(b));                            \
		(v).n += ((v).data[w] == WORD_MAX);                            \
		if ((v).n == (v).m) {                                          \
			(v).m = (v).m + 1;                                     \
			(v).data = realloc((v).data, (v).m * sizeof(word_t));  \
		}                                                              \
	} while (0)

/* Find a clear bit in v and assign it to b. */
#define bf_find_bit(v, b)                                                      \
	do {                                                                   \
		word_t word = 0;                                               \
		unsigned int w, sh;                                            \
		for (w = 0; w <= (v).n; w++) {                                 \
			if ((word = (v).data[w]) != WORD_MAX)                  \
				break;                                         \
		}                                                              \
		(b) = ((word & 0xFFFF) == 0xFFFF) << 4;                        \
		word >>= (b);                                                  \
		sh = ((word & 0xFF) == 0xFF) << 3;                             \
		word >>= sh;                                                   \
		(b) |= sh;                                                     \
		sh = ((word & 0xF) == 0xF) << 2;                               \
		word >>= sh;                                                   \
		(b) |= sh;                                                     \
		sh = ((word & 0x3) == 0x3) << 1;                               \
		word >>= sh;                                                   \
		(b) |= sh;                                                     \
		sh = ((word & 0x1) == 0x1) << 0;                               \
		word >>= sh;                                                   \
		(b) |= sh;                                                     \
		(b) += (w * WORD_SIZE);                                        \
	} while (0)

/*
 * Find a clear bit in v and return it
 * Start looking in the word containing bit position start_index.
 * If necessary, wrap around after bit position max_index.
 */
static inline unsigned int
bf_find_next_clear_bit_wrap(bitfield_t *v, word_t start_index, word_t max_index)
{
	int start_bit;
	unsigned long i, offset, scanbits, wordcount_max, index_max;

	if (start_index > max_index)
		start_index = 0;

	start_bit = start_index & (WORD_SIZE - 1);
	wordcount_max = bf_index(max_index) + 1;

	scanbits = WORD_SIZE;
	for (i = bf_index(start_index); i < v->m; ++i) {
		if (v->data[i] == WORD_MAX) {
			/* if the whole word is full move to the next */
			start_bit = 0;
			continue;
		}
		/* scan one word for clear bits */
		if ((i == v->m - 1) && (v->m >= wordcount_max))
			/* max index could be only part of word */
			scanbits = (max_index % WORD_SIZE) + 1;
		for (offset = start_bit; offset < scanbits; ++offset) {
			if (!((v->data[i] >> offset) & 1))
				return ((i * WORD_SIZE) + offset);
		}
		/* move to the next word */
		start_bit = 0;
	}

	if (v->m < wordcount_max) {
		/*
		 * We can expand bitfield, so no need to wrap.
		 * Return the index of the first bit of the next word.
		 * Assumption is that caller will call bf_set_bit which
		 * will allocate additional space.
		 */
		v->m += 1;
		v->data = (word_t *)realloc(v->data, v->m * sizeof(word_t));
		v->data[v->m - 1] = 0;
		return v->m * WORD_SIZE;
	}

	/*
	 * start looking for a clear bit at the start of the bitfield and
	 * stop when we reach start_index
	 */
	scanbits = WORD_SIZE;
	index_max = bf_index(start_index - 1);
	for (i = 0; i <= index_max; ++i) {
		if (i == index_max)
			scanbits = ((start_index - 1) % WORD_SIZE) + 1;
		for (offset = start_bit; offset < scanbits; ++offset) {
			if (!((v->data[i] >> offset) & 1))
				return ((i * WORD_SIZE) + offset);
		}
		/* move to the next word */
		start_bit = 0;
	}

	return WORD_MAX;
}

static inline unsigned int bf_find_next_set_bit(bitfield_t v,
		word_t start_index)
{
	int start_bit;
	unsigned long i, offset;

	start_bit = start_index & (WORD_SIZE - 1);

	for (i = bf_index(start_index); i < v.m; ++i) {
		if (v.data[i] == 0) {
			/* if the whole word is empty move to the next */
			start_bit = 0;
			continue;
		}
		/* scan one word for set bits */
		for (offset = start_bit; offset < WORD_SIZE; ++offset) {
			if ((v.data[i] >> offset) & 1)
				return ((i * WORD_SIZE) + offset);
		}
		/* move to the next word */
		start_bit = 0;
	}
	return WORD_MAX;
}

/* iterate through all the set bits */
#define bf_for_each_set_bit(v, b, max)                 \
	for ((b) = bf_find_next_set_bit((v), 0);           \
			(b) < max;                                 \
			(b) = bf_find_next_set_bit((v), (b) + 1))

/*
 * Free the allocated memory for data
 * @v: an instance of bitfield_t struct.
 */
#define bf_free(v)                                                             \
	do {                                                                   \
		XFREE(MTYPE_BITFIELD, (v).data);                               \
		(v).data = NULL;                                               \
	} while (0)

#ifdef __cplusplus
}
#endif

#endif
Commit	Line	Data
50e24903 DS	1	/* Bitfields
	2	* Copyright (C) 2016 Cumulus Networks, Inc.
	3	*
	4	* This file is part of Quagga.
	5	*
	6	* Quagga is free software; you can redistribute it and/or modify it
	7	* under the terms of the GNU General Public License as published by the
	8	* Free Software Foundation; either version 2, or (at your option) any
	9	* later version.
	10	*
	11	* Quagga is distributed in the hope that it will be useful, but
	12	* WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	* General Public License for more details.
	15	*
896014f4 DL	16	* You should have received a copy of the GNU General Public License along
	17	* with this program; see the file COPYING; if not, write to the Free Software
	18	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
50e24903	19	*/
c3c0ac83 DS	20	/**
	21	* A simple bit array implementation to allocate and free IDs. An example
	22	* of its usage is in allocating link state IDs for OSPFv3 as OSPFv3 has
	23	* removed all address semantics from LS ID. Another usage can be in
	24	* allocating IDs for BGP neighbors (and dynamic update groups) for
	25	* efficient storage of adj-rib-out.
	26	*
	27	* An example:
	28	* #include "bitfield.h"
	29	*
	30	* bitfield_t bitfield;
	31	*
	32	* bf_init(bitfield, 32);
	33	* ...
	34	* bf_assign_index(bitfield, id1);
	35	* bf_assign_index(bitfield, id2);
	36	* ...
	37	* bf_release_index(bitfield, id1);
	38	*/
	39
	40	#ifndef _BITFIELD_H
	41	#define _BITFIELD_H
	42
	43	#include <stdio.h>
	44	#include <string.h>
	45	#include <stdlib.h>
	46
5e244469 RW	47	#ifdef __cplusplus
	48	extern "C" {
	49	#endif
	50
c3c0ac83 DS	51	typedef unsigned int word_t;
	52	#define WORD_MAX 0xFFFFFFFF
	53	#define WORD_SIZE (sizeof(word_t) * 8)
	54
	55	/**
	56	* The bitfield structure.
	57	* @data: the bits to manage.
	58	* @n: The current word number that is being used.
	59	* @m: total number of words in 'data'
	60	*/
89fbf168	61	typedef struct {word_t *data; size_t n, m; } bitfield_t;
c3c0ac83	62
0e2deb58 PR	63	DECLARE_MTYPE(BITFIELD);
0e2deb58 PR	64
c3c0ac83 DS	65	/**
	66	* Initialize the bits.
	67	* @v: an instance of bitfield_t struct.
	68	* @N: number of bits to start with, which equates to how many
	69	* IDs can be allocated.
	70	*/
d62a17ae	71	#define bf_init(v, N) \
	72	do { \
	73	(v).n = 0; \
	74	(v).m = ((N) / WORD_SIZE + 1); \
0e2deb58	75	(v).data = XCALLOC(MTYPE_BITFIELD, ((v).m * sizeof(word_t))); \
d62a17ae	76	} while (0)
c3c0ac83 DS	77
	78	/**
	79	* allocate and assign an id from bitfield v.
	80	*/
d62a17ae	81	#define bf_assign_index(v, id) \
	82	do { \
	83	bf_find_bit(v, id); \
	84	bf_set_bit(v, id); \
	85	} while (0)
c3c0ac83	86
4e9da201	87	/*
	88	* allocate and assign 0th bit in the bitfiled.
	89	*/
d62a17ae	90	#define bf_assign_zero_index(v) \
	91	do { \
	92	int id = 0; \
	93	bf_assign_index(v, id); \
	94	} while (0)
4e9da201	95
4e9da201	96	/*
c3c0ac83 DS	97	* return an id to bitfield v
c3c0ac83 DS	98	*/
d62a17ae	99	#define bf_release_index(v, id) \
d62a17ae	100	(v).data[bf_index(id)] &= ~(1 << (bf_offset(id)))
c3c0ac83	101
89fbf168 AK	102	/* check if an id is in use */
	103	#define bf_test_index(v, id) \
	104	((v).data[bf_index(id)] & (1 << (bf_offset(id))))
	105
	106	/* check if the bit field has been setup */
	107	#define bf_is_inited(v) ((v).data)
	108
	109	/* compare two bitmaps of the same length */
	110	#define bf_cmp(v1, v2) (memcmp((v1).data, (v2).data, ((v1).m * sizeof(word_t))))
	111
4e9da201	112	/*
	113	* return 0th index back to bitfield
	114	*/
d62a17ae	115	#define bf_release_zero_index(v) bf_release_index(v, 0)
4e9da201	116
c3c0ac83 DS	117	#define bf_index(b) ((b) / WORD_SIZE)
	118	#define bf_offset(b) ((b) % WORD_SIZE)
	119
	120	/**
	121	* Set a bit in the array. If it fills up that word and we are
	122	* out of words, extend it by one more word.
	123	*/
d62a17ae	124	#define bf_set_bit(v, b) \
	125	do { \
	126	size_t w = bf_index(b); \
	127	(v).data[w] \|= 1 << (bf_offset(b)); \
	128	(v).n += ((v).data[w] == WORD_MAX); \
	129	if ((v).n == (v).m) { \
	130	(v).m = (v).m + 1; \
	131	(v).data = realloc((v).data, (v).m * sizeof(word_t)); \
	132	} \
	133	} while (0)
c3c0ac83 DS	134
c3c0ac83 DS	135	/* Find a clear bit in v and assign it to b. */
d62a17ae	136	#define bf_find_bit(v, b) \
	137	do { \
	138	word_t word = 0; \
	139	unsigned int w, sh; \
	140	for (w = 0; w <= (v).n; w++) { \
	141	if ((word = (v).data[w]) != WORD_MAX) \
	142	break; \
	143	} \
	144	(b) = ((word & 0xFFFF) == 0xFFFF) << 4; \
	145	word >>= (b); \
	146	sh = ((word & 0xFF) == 0xFF) << 3; \
	147	word >>= sh; \
	148	(b) \|= sh; \
	149	sh = ((word & 0xF) == 0xF) << 2; \
	150	word >>= sh; \
	151	(b) \|= sh; \
	152	sh = ((word & 0x3) == 0x3) << 1; \
	153	word >>= sh; \
	154	(b) \|= sh; \
	155	sh = ((word & 0x1) == 0x1) << 0; \
	156	word >>= sh; \
	157	(b) \|= sh; \
	158	(b) += (w * WORD_SIZE); \
	159	} while (0)
c3c0ac83	160
80853c2e PZ	161	/*
	162	* Find a clear bit in v and return it
	163	* Start looking in the word containing bit position start_index.
	164	* If necessary, wrap around after bit position max_index.
	165	*/
	166	static inline unsigned int
	167	bf_find_next_clear_bit_wrap(bitfield_t *v, word_t start_index, word_t max_index)
	168	{
	169	int start_bit;
	170	unsigned long i, offset, scanbits, wordcount_max, index_max;
	171
	172	if (start_index > max_index)
	173	start_index = 0;
	174
	175	start_bit = start_index & (WORD_SIZE - 1);
	176	wordcount_max = bf_index(max_index) + 1;
	177
	178	scanbits = WORD_SIZE;
	179	for (i = bf_index(start_index); i < v->m; ++i) {
	180	if (v->data[i] == WORD_MAX) {
	181	/* if the whole word is full move to the next */
	182	start_bit = 0;
	183	continue;
	184	}
	185	/* scan one word for clear bits */
	186	if ((i == v->m - 1) && (v->m >= wordcount_max))
	187	/* max index could be only part of word */
	188	scanbits = (max_index % WORD_SIZE) + 1;
	189	for (offset = start_bit; offset < scanbits; ++offset) {
	190	if (!((v->data[i] >> offset) & 1))
	191	return ((i * WORD_SIZE) + offset);
	192	}
	193	/* move to the next word */
	194	start_bit = 0;
	195	}
	196
	197	if (v->m < wordcount_max) {
	198	/*
	199	* We can expand bitfield, so no need to wrap.
	200	* Return the index of the first bit of the next word.
	201	* Assumption is that caller will call bf_set_bit which
	202	* will allocate additional space.
	203	*/
	204	v->m += 1;
	205	v->data = (word_t )realloc(v->data, v->m sizeof(word_t));
	206	v->data[v->m - 1] = 0;
	207	return v->m * WORD_SIZE;
	208	}
	209
	210	/*
	211	* start looking for a clear bit at the start of the bitfield and
	212	* stop when we reach start_index
	213	*/
	214	scanbits = WORD_SIZE;
	215	index_max = bf_index(start_index - 1);
	216	for (i = 0; i <= index_max; ++i) {
	217	if (i == index_max)
	218	scanbits = ((start_index - 1) % WORD_SIZE) + 1;
	219	for (offset = start_bit; offset < scanbits; ++offset) {
	220	if (!((v->data[i] >> offset) & 1))
	221	return ((i * WORD_SIZE) + offset);
	222	}
	223	/* move to the next word */
	224	start_bit = 0;
225	}
226
227	return WORD_MAX;
228	}
229
89fbf168 AK	230	static inline unsigned int bf_find_next_set_bit(bitfield_t v,
	231	word_t start_index)
	232	{
	233	int start_bit;
	234	unsigned long i, offset;
	235
	236	start_bit = start_index & (WORD_SIZE - 1);
	237
	238	for (i = bf_index(start_index); i < v.m; ++i) {
	239	if (v.data[i] == 0) {
	240	/* if the whole word is empty move to the next */
	241	start_bit = 0;
	242	continue;
	243	}
	244	/* scan one word for set bits */
	245	for (offset = start_bit; offset < WORD_SIZE; ++offset) {
	246	if ((v.data[i] >> offset) & 1)
	247	return ((i * WORD_SIZE) + offset);
	248	}
	249	/* move to the next word */
	250	start_bit = 0;
	251	}
	252	return WORD_MAX;
	253	}
	254
	255	/* iterate through all the set bits */
	256	#define bf_for_each_set_bit(v, b, max) \
	257	for ((b) = bf_find_next_set_bit((v), 0); \
	258	(b) < max; \
	259	(b) = bf_find_next_set_bit((v), (b) + 1))
	260
4e9da201	261	/*
	262	* Free the allocated memory for data
	263	* @v: an instance of bitfield_t struct.
	264	*/
d62a17ae	265	#define bf_free(v) \
d62a17ae	266	do { \
0e2deb58	267	XFREE(MTYPE_BITFIELD, (v).data); \
1ac10b15	268	(v).data = NULL; \
d62a17ae	269	} while (0)
4e9da201	270
5e244469 RW	271	#ifdef __cplusplus
	272	}
	273	#endif
	274
c3c0ac83	275	#endif