/contrib/bind9/lib/isc/bitstring.c
https://bitbucket.org/freebsd/freebsd-head/ · C · 127 lines · 73 code · 20 blank · 34 comment · 9 complexity · 5eaf9ab41ba86c7f357f7a203d0cb1b3 MD5 · raw file
- /*
- * Copyright (C) 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
- * Copyright (C) 1999-2001 Internet Software Consortium.
- *
- * Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
- * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
- * AND FITNESS. IN NO EVENT SHALL ISC 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 1.17 2007/06/19 23:47:17 tbox Exp $ */
- /*! \file */
- #include <config.h>
- #include <stddef.h>
- #include <isc/magic.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 ISC_MAGIC('B', 'S', 't', 'r')
- #define VALID_BITSTRING(b) ISC_MAGIC_VALID(b, 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--;
- }
- }