128 lines
3.4 KiB
C
128 lines
3.4 KiB
C
/*
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* Copyright (C) 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
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* Copyright (C) 1999-2001 Internet Software Consortium.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
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* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
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* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
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* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
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* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
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* PERFORMANCE OF THIS SOFTWARE.
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*/
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/* $Id: bitstring.c,v 1.17 2007/06/19 23:47:17 tbox Exp $ */
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/*! \file */
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#include <config.h>
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#include <stddef.h>
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#include <isc/magic.h>
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#include <isc/bitstring.h>
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#include <isc/util.h>
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#define DIV8(x) ((x) >> 3)
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#define MOD8(x) ((x) & 0x00000007U)
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#define OCTETS(n) (((n) + 7) >> 3)
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#define PADDED(n) ((((n) + 7) >> 3) << 3)
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#define BITSET(bs, n) (((bs)->data[DIV8(n)] & \
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(1 << (7 - MOD8(n)))) != 0)
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#define SETBIT(bs, n) (bs)->data[DIV8(n)] |= (1 << (7 - MOD8(n)))
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#define CLEARBIT(bs, n) (bs)->data[DIV8(n)] &= ~(1 << (7 - MOD8(n)))
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#define BITSTRING_MAGIC ISC_MAGIC('B', 'S', 't', 'r')
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#define VALID_BITSTRING(b) ISC_MAGIC_VALID(b, BITSTRING_MAGIC)
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void
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isc_bitstring_init(isc_bitstring_t *bitstring, unsigned char *data,
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unsigned int length, unsigned int size, isc_boolean_t lsb0)
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{
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/*
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* Make 'bitstring' refer to the bitstring of 'size' bits starting
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* at 'data'. 'length' bits of the bitstring are valid. If 'lsb0'
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* is set then, bit 0 refers to the least significant bit of the
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* bitstring. Otherwise bit 0 is the most significant bit.
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*/
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REQUIRE(bitstring != NULL);
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REQUIRE(data != NULL);
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REQUIRE(length <= size);
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bitstring->magic = BITSTRING_MAGIC;
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bitstring->data = data;
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bitstring->length = length;
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bitstring->size = size;
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bitstring->lsb0 = lsb0;
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}
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void
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isc_bitstring_invalidate(isc_bitstring_t *bitstring) {
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/*
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* Invalidate 'bitstring'.
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*/
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REQUIRE(VALID_BITSTRING(bitstring));
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bitstring->magic = 0;
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bitstring->data = NULL;
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bitstring->length = 0;
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bitstring->size = 0;
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bitstring->lsb0 = ISC_FALSE;
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}
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void
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isc_bitstring_copy(isc_bitstring_t *source, unsigned int sbitpos,
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isc_bitstring_t *target, unsigned int tbitpos,
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unsigned int n)
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{
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unsigned int tlast;
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/*
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* Starting at bit 'sbitpos', copy 'n' bits from 'source' to
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* the 'n' bits of 'target' starting at 'tbitpos'.
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*/
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REQUIRE(VALID_BITSTRING(source));
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REQUIRE(VALID_BITSTRING(target));
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REQUIRE(source->lsb0 == target->lsb0);
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if (source->lsb0) {
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REQUIRE(sbitpos <= source->length);
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sbitpos = PADDED(source->size) - sbitpos;
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REQUIRE(sbitpos >= n);
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sbitpos -= n;
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} else
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REQUIRE(sbitpos + n <= source->length);
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tlast = tbitpos + n;
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if (target->lsb0) {
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REQUIRE(tbitpos <= target->length);
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tbitpos = PADDED(target->size) - tbitpos;
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REQUIRE(tbitpos >= n);
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tbitpos -= n;
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} else
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REQUIRE(tlast <= target->size);
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if (tlast > target->length)
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target->length = tlast;
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/*
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* This is far from optimal...
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*/
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while (n > 0) {
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if (BITSET(source, sbitpos))
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SETBIT(target, tbitpos);
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else
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CLEARBIT(target, tbitpos);
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sbitpos++;
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tbitpos++;
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n--;
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}
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}
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