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/* $OpenBSD: bitmap.c,v 1.9 2017/10/20 01:56:39 djm Exp $ */
/*
* Copyright (c) 2015 Damien Miller <djm@mindrot.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "includes.h"
#include <sys/types.h>
#include <string.h>
#include <stdlib.h>
#include "bitmap.h"
#define BITMAP_WTYPE u_int
#define BITMAP_MAX (1<<24)
#define BITMAP_BYTES (sizeof(BITMAP_WTYPE))
#define BITMAP_BITS (sizeof(BITMAP_WTYPE) * 8)
#define BITMAP_WMASK ((BITMAP_WTYPE)BITMAP_BITS - 1)
struct bitmap {
BITMAP_WTYPE *d;
size_t len; /* number of words allocated */
size_t top; /* index of top word allocated */
};
struct bitmap *
bitmap_new(void)
{
struct bitmap *ret;
if ((ret = calloc(1, sizeof(*ret))) == NULL)
return NULL;
if ((ret->d = calloc(1, BITMAP_BYTES)) == NULL) {
free(ret);
return NULL;
}
ret->len = 1;
ret->top = 0;
return ret;
}
void
bitmap_free(struct bitmap *b)
{
if (b != NULL && b->d != NULL) {
bitmap_zero(b);
free(b->d);
b->d = NULL;
}
free(b);
}
void
bitmap_zero(struct bitmap *b)
{
memset(b->d, 0, b->len * BITMAP_BYTES);
b->top = 0;
}
int
bitmap_test_bit(struct bitmap *b, u_int n)
{
if (b->top >= b->len)
return 0; /* invalid */
if (b->len == 0 || (n / BITMAP_BITS) > b->top)
return 0;
return (b->d[n / BITMAP_BITS] >> (n & BITMAP_WMASK)) & 1;
}
static int
reserve(struct bitmap *b, u_int n)
{
BITMAP_WTYPE *tmp;
size_t nlen;
if (b->top >= b->len || n > BITMAP_MAX)
return -1; /* invalid */
nlen = (n / BITMAP_BITS) + 1;
if (b->len < nlen) {
if ((tmp = recallocarray(b->d, b->len,
nlen, BITMAP_BYTES)) == NULL)
return -1;
b->d = tmp;
b->len = nlen;
}
return 0;
}
int
bitmap_set_bit(struct bitmap *b, u_int n)
{
int r;
size_t offset;
if ((r = reserve(b, n)) != 0)
return r;
offset = n / BITMAP_BITS;
if (offset > b->top)
b->top = offset;
b->d[offset] |= (BITMAP_WTYPE)1 << (n & BITMAP_WMASK);
return 0;
}
/* Resets b->top to point to the most significant bit set in b->d */
static void
retop(struct bitmap *b)
{
if (b->top >= b->len)
return;
while (b->top > 0 && b->d[b->top] == 0)
b->top--;
}
void
bitmap_clear_bit(struct bitmap *b, u_int n)
{
size_t offset;
if (b->top >= b->len || n > BITMAP_MAX)
return; /* invalid */
offset = n / BITMAP_BITS;
if (offset > b->top)
return;
b->d[offset] &= ~((BITMAP_WTYPE)1 << (n & BITMAP_WMASK));
/* The top may have changed as a result of the clear */
retop(b);
}
size_t
bitmap_nbits(struct bitmap *b)
{
size_t bits;
BITMAP_WTYPE w;
retop(b);
if (b->top >= b->len)
return 0; /* invalid */
if (b->len == 0 || (b->top == 0 && b->d[0] == 0))
return 0;
/* Find MSB set */
w = b->d[b->top];
bits = (b->top + 1) * BITMAP_BITS;
while (!(w & ((BITMAP_WTYPE)1 << (BITMAP_BITS - 1)))) {
w <<= 1;
bits--;
}
return bits;
}
size_t
bitmap_nbytes(struct bitmap *b)
{
return (bitmap_nbits(b) + 7) / 8;
}
int
bitmap_to_string(struct bitmap *b, void *p, size_t l)
{
u_char *s = (u_char *)p;
size_t i, j, k, need = bitmap_nbytes(b);
if (l < need || b->top >= b->len)
return -1;
if (l > need)
l = need;
/* Put the bytes from LSB backwards */
for (i = k = 0; i < b->top + 1; i++) {
for (j = 0; j < BITMAP_BYTES; j++) {
if (k >= l)
break;
s[need - 1 - k++] = (b->d[i] >> (j * 8)) & 0xff;
}
}
return 0;
}
int
bitmap_from_string(struct bitmap *b, const void *p, size_t l)
{
int r;
size_t i, offset, shift;
const u_char *s = (const u_char *)p;
if (l > BITMAP_MAX / 8)
return -1;
if ((r = reserve(b, l * 8)) != 0)
return r;
bitmap_zero(b);
if (l == 0)
return 0;
b->top = offset = ((l + (BITMAP_BYTES - 1)) / BITMAP_BYTES) - 1;
shift = ((l + (BITMAP_BYTES - 1)) % BITMAP_BYTES) * 8;
for (i = 0; i < l; i++) {
b->d[offset] |= (BITMAP_WTYPE)s[i] << shift;
if (shift == 0) {
offset--;
shift = BITMAP_BITS - 8;
} else
shift -= 8;
}
retop(b);
return 0;
}
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