1 /* $NetBSD: bitmap.c,v 1.2 2015/04/03 23:58:19 christos Exp $ */ 2 /* 3 * Copyright (c) 2015 Damien Miller <djm@mindrot.org> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 #include "includes.h" 18 __RCSID("$NetBSD: bitmap.c,v 1.2 2015/04/03 23:58:19 christos Exp $"); 19 20 #include <sys/types.h> 21 #include <string.h> 22 #include <stdlib.h> 23 24 #include "bitmap.h" 25 26 #define BITMAP_WTYPE u_int 27 #define BITMAP_MAX (1<<24) 28 #define BITMAP_BYTES (sizeof(BITMAP_WTYPE)) 29 #define BITMAP_BITS (sizeof(BITMAP_WTYPE) * 8) 30 #define BITMAP_WMASK ((BITMAP_WTYPE)BITMAP_BITS - 1) 31 struct bitmap { 32 BITMAP_WTYPE *d; 33 size_t len; /* number of words allocated */ 34 size_t top; /* index of top word allocated */ 35 }; 36 37 struct bitmap * 38 bitmap_new(void) 39 { 40 struct bitmap *ret; 41 42 if ((ret = calloc(1, sizeof(*ret))) == NULL) 43 return NULL; 44 if ((ret->d = calloc(1, BITMAP_BYTES)) == NULL) { 45 free(ret); 46 return NULL; 47 } 48 ret->len = 1; 49 ret->top = 0; 50 return ret; 51 } 52 53 void 54 bitmap_free(struct bitmap *b) 55 { 56 if (b != NULL && b->d != NULL) { 57 memset(b->d, 0, b->len); 58 free(b->d); 59 } 60 free(b); 61 } 62 63 void 64 bitmap_zero(struct bitmap *b) 65 { 66 memset(b->d, 0, b->len * BITMAP_BYTES); 67 b->top = 0; 68 } 69 70 int 71 bitmap_test_bit(struct bitmap *b, u_int n) 72 { 73 if (b->top >= b->len) 74 return 0; /* invalid */ 75 if (b->len == 0 || (n / BITMAP_BITS) > b->top) 76 return 0; 77 return (b->d[n / BITMAP_BITS] >> (n & BITMAP_WMASK)) & 1; 78 } 79 80 static int 81 reserve(struct bitmap *b, u_int n) 82 { 83 BITMAP_WTYPE *tmp; 84 size_t nlen; 85 86 if (b->top >= b->len || n > BITMAP_MAX) 87 return -1; /* invalid */ 88 nlen = (n / BITMAP_BITS) + 1; 89 if (b->len < nlen) { 90 if ((tmp = reallocarray(b->d, nlen, BITMAP_BYTES)) == NULL) 91 return -1; 92 b->d = tmp; 93 memset(b->d + b->len, 0, (nlen - b->len) * BITMAP_BYTES); 94 b->len = nlen; 95 } 96 return 0; 97 } 98 99 int 100 bitmap_set_bit(struct bitmap *b, u_int n) 101 { 102 int r; 103 size_t offset; 104 105 if ((r = reserve(b, n)) != 0) 106 return r; 107 offset = n / BITMAP_BITS; 108 if (offset > b->top) 109 b->top = offset; 110 b->d[offset] |= (BITMAP_WTYPE)1 << (n & BITMAP_WMASK); 111 return 0; 112 } 113 114 /* Resets b->top to point to the most significant bit set in b->d */ 115 static void 116 retop(struct bitmap *b) 117 { 118 if (b->top >= b->len) 119 return; 120 while (b->top > 0 && b->d[b->top] == 0) 121 b->top--; 122 } 123 124 void 125 bitmap_clear_bit(struct bitmap *b, u_int n) 126 { 127 size_t offset; 128 129 if (b->top >= b->len || n > BITMAP_MAX) 130 return; /* invalid */ 131 offset = n / BITMAP_BITS; 132 if (offset > b->top) 133 return; 134 b->d[offset] &= ~((BITMAP_WTYPE)1 << (n & BITMAP_WMASK)); 135 /* The top may have changed as a result of the clear */ 136 retop(b); 137 } 138 139 size_t 140 bitmap_nbits(struct bitmap *b) 141 { 142 size_t bits; 143 BITMAP_WTYPE w; 144 145 retop(b); 146 if (b->top >= b->len) 147 return 0; /* invalid */ 148 if (b->len == 0 || (b->top == 0 && b->d[0] == 0)) 149 return 0; 150 /* Find MSB set */ 151 w = b->d[b->top]; 152 bits = (b->top + 1) * BITMAP_BITS; 153 while (!(w & ((BITMAP_WTYPE)1 << (BITMAP_BITS - 1)))) { 154 w <<= 1; 155 bits--; 156 } 157 return bits; 158 } 159 160 size_t 161 bitmap_nbytes(struct bitmap *b) 162 { 163 return (bitmap_nbits(b) + 7) / 8; 164 } 165 166 int 167 bitmap_to_string(struct bitmap *b, void *p, size_t l) 168 { 169 u_char *s = (u_char *)p; 170 size_t i, j, k, need = bitmap_nbytes(b); 171 172 if (l < need || b->top >= b->len) 173 return -1; 174 if (l > need) 175 l = need; 176 /* Put the bytes from LSB backwards */ 177 for (i = k = 0; i < b->top + 1; i++) { 178 for (j = 0; j < BITMAP_BYTES; j++) { 179 if (k >= l) 180 break; 181 s[need - 1 - k++] = (b->d[i] >> (j * 8)) & 0xff; 182 } 183 } 184 return 0; 185 } 186 187 int 188 bitmap_from_string(struct bitmap *b, const void *p, size_t l) 189 { 190 int r; 191 size_t i, offset, shift; 192 const u_char *s = p; 193 194 if (l > BITMAP_MAX / 8) 195 return -1; 196 if ((r = reserve(b, l * 8)) != 0) 197 return r; 198 bitmap_zero(b); 199 if (l == 0) 200 return 0; 201 b->top = offset = ((l + (BITMAP_BYTES - 1)) / BITMAP_BYTES) - 1; 202 shift = ((l + (BITMAP_BYTES - 1)) % BITMAP_BYTES) * 8; 203 for (i = 0; i < l; i++) { 204 b->d[offset] |= (BITMAP_WTYPE)s[i] << shift; 205 if (shift == 0) { 206 offset--; 207 shift = BITMAP_BITS - 8; 208 } else 209 shift -= 8; 210 } 211 retop(b); 212 return 0; 213 } 214