bitstring.c revision 499b34cea04a46823d003d4c0520c8b03e8513cb
/*
* Copyright (C) 1999-2001 Internet Software Consortium.
*
* 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 INTERNET SOFTWARE CONSORTIUM
* DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
* INTERNET SOFTWARE CONSORTIUM 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.
*/
/* $Id: bitstring.c,v 1.11 2001/01/09 21:55:55 bwelling Exp $ */
#include <config.h>
#include <stddef.h>
#include <isc/bitstring.h>
#include <isc/util.h>
#define DIV8(x) ((x) >> 3)
#define MOD8(x) ((x) & 0x00000007U)
#define OCTETS(n) (((n) + 7) >> 3)
#define PADDED(n) ((((n) + 7) >> 3) << 3)
#define BITSET(bs, n) (((bs)->data[DIV8(n)] & \
(1 << (7 - MOD8(n)))) != 0)
#define SETBIT(bs, n) (bs)->data[DIV8(n)] |= (1 << (7 - MOD8(n)))
#define CLEARBIT(bs, n) (bs)->data[DIV8(n)] &= ~(1 << (7 - MOD8(n)))
#define BITSTRING_MAGIC 0x42537472U /* BStr. */
#define VALID_BITSTRING(b) ((b) != NULL && \
(b)->magic == BITSTRING_MAGIC)
void
isc_bitstring_init(isc_bitstring_t *bitstring, unsigned char *data,
unsigned int length, unsigned int size, isc_boolean_t lsb0)
{
/*
* Make 'bitstring' refer to the bitstring of 'size' bits starting
* at 'data'. 'length' bits of the bitstring are valid. If 'lsb0'
* is set then, bit 0 refers to the least significant bit of the
* bitstring. Otherwise bit 0 is the most significant bit.
*/
REQUIRE(bitstring != NULL);
REQUIRE(data != NULL);
REQUIRE(length <= size);
bitstring->magic = BITSTRING_MAGIC;
bitstring->data = data;
bitstring->length = length;
bitstring->size = size;
bitstring->lsb0 = lsb0;
}
void
isc_bitstring_invalidate(isc_bitstring_t *bitstring) {
/*
* Invalidate 'bitstring'.
*/
REQUIRE(VALID_BITSTRING(bitstring));
bitstring->magic = 0;
bitstring->data = NULL;
bitstring->length = 0;
bitstring->size = 0;
bitstring->lsb0 = ISC_FALSE;
}
void
isc_bitstring_copy(isc_bitstring_t *source, unsigned int sbitpos,
isc_bitstring_t *target, unsigned int tbitpos,
unsigned int n)
{
unsigned int tlast;
/*
* Starting at bit 'sbitpos', copy 'n' bits from 'source' to
* the 'n' bits of 'target' starting at 'tbitpos'.
*/
REQUIRE(VALID_BITSTRING(source));
REQUIRE(VALID_BITSTRING(target));
REQUIRE(source->lsb0 == target->lsb0);
if (source->lsb0) {
REQUIRE(sbitpos <= source->length);
sbitpos = PADDED(source->size) - sbitpos;
REQUIRE(sbitpos >= n);
sbitpos -= n;
} else
REQUIRE(sbitpos + n <= source->length);
tlast = tbitpos + n;
if (target->lsb0) {
REQUIRE(tbitpos <= target->length);
tbitpos = PADDED(target->size) - tbitpos;
REQUIRE(tbitpos >= n);
tbitpos -= n;
} else
REQUIRE(tlast <= target->size);
if (tlast > target->length)
target->length = tlast;
/*
* This is far from optimal...
*/
while (n > 0) {
if (BITSET(source, sbitpos))
SETBIT(target, tbitpos);
else
CLEARBIT(target, tbitpos);
sbitpos++;
tbitpos++;
n--;
}
}