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