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ntp 4.2.6p5

    1: /*
    2:  * Copyright (C) 2004, 2005, 2007  Internet Systems Consortium, Inc. ("ISC")
    3:  * Copyright (C) 1999-2001  Internet Software Consortium.
    4:  *
    5:  * Permission to use, copy, modify, and/or distribute this software for any
    6:  * purpose with or without fee is hereby granted, provided that the above
    7:  * copyright notice and this permission notice appear in all copies.
    8:  *
    9:  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
   10:  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
   11:  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
   12:  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
   13:  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
   14:  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
   15:  * PERFORMANCE OF THIS SOFTWARE.
   16:  */
   17: 
   18: /* $Id: bitstring.c,v 1.1.1.1 2012/05/29 12:08:38 misho Exp $ */
   19: 
   20: /*! \file */
   21: 
   22: #include <config.h>
   23: 
   24: #include <stddef.h>
   25: 
   26: #include <isc/magic.h>
   27: #include <isc/bitstring.h>
   28: #include <isc/util.h>
   29: 
   30: #define DIV8(x)			((x) >> 3)
   31: #define MOD8(x)			((x) & 0x00000007U)
   32: #define OCTETS(n)		(((n) + 7) >> 3)
   33: #define PADDED(n)		((((n) + 7) >> 3) << 3)
   34: #define BITSET(bs, n) 		(((bs)->data[DIV8(n)] & \
   35: 				 (1 << (7 - MOD8(n)))) != 0)
   36: #define SETBIT(bs, n)		(bs)->data[DIV8(n)] |= (1 << (7 - MOD8(n)))
   37: #define CLEARBIT(bs, n)		(bs)->data[DIV8(n)] &= ~(1 << (7 - MOD8(n)))
   38: 
   39: #define BITSTRING_MAGIC		ISC_MAGIC('B', 'S', 't', 'r')
   40: #define VALID_BITSTRING(b)	ISC_MAGIC_VALID(b, BITSTRING_MAGIC)
   41: 
   42: void
   43: isc_bitstring_init(isc_bitstring_t *bitstring, unsigned char *data,
   44: 		   unsigned int length, unsigned int size, isc_boolean_t lsb0)
   45: {
   46: 	/*
   47: 	 * Make 'bitstring' refer to the bitstring of 'size' bits starting
   48: 	 * at 'data'.  'length' bits of the bitstring are valid.  If 'lsb0'
   49: 	 * is set then, bit 0 refers to the least significant bit of the
   50: 	 * bitstring.  Otherwise bit 0 is the most significant bit.
   51: 	 */
   52: 
   53: 	REQUIRE(bitstring != NULL);
   54: 	REQUIRE(data != NULL);
   55: 	REQUIRE(length <= size);
   56: 
   57: 	bitstring->magic = BITSTRING_MAGIC;
   58: 	bitstring->data = data;
   59: 	bitstring->length = length;
   60: 	bitstring->size = size;
   61: 	bitstring->lsb0 = lsb0;
   62: }
   63: 
   64: void
   65: isc_bitstring_invalidate(isc_bitstring_t *bitstring) {
   66: 
   67: 	/*
   68: 	 * Invalidate 'bitstring'.
   69: 	 */
   70: 
   71: 	REQUIRE(VALID_BITSTRING(bitstring));
   72: 
   73: 	bitstring->magic = 0;
   74: 	bitstring->data = NULL;
   75: 	bitstring->length = 0;
   76: 	bitstring->size = 0;
   77: 	bitstring->lsb0 = ISC_FALSE;
   78: }
   79: 
   80: void
   81: isc_bitstring_copy(isc_bitstring_t *source, unsigned int sbitpos,
   82: 		   isc_bitstring_t *target, unsigned int tbitpos,
   83: 		   unsigned int n)
   84: {
   85: 	unsigned int tlast;
   86: 
   87: 	/*
   88: 	 * Starting at bit 'sbitpos', copy 'n' bits from 'source' to
   89: 	 * the 'n' bits of 'target' starting at 'tbitpos'.
   90: 	 */
   91: 
   92: 	REQUIRE(VALID_BITSTRING(source));
   93: 	REQUIRE(VALID_BITSTRING(target));
   94: 	REQUIRE(source->lsb0 == target->lsb0);
   95: 	if (source->lsb0) {
   96: 		REQUIRE(sbitpos <= source->length);
   97: 		sbitpos = PADDED(source->size) - sbitpos;
   98: 		REQUIRE(sbitpos >= n);
   99: 		sbitpos -= n;
  100: 	} else
  101: 		REQUIRE(sbitpos + n <= source->length);
  102: 	tlast = tbitpos + n;
  103: 	if (target->lsb0) {
  104: 		REQUIRE(tbitpos <= target->length);
  105: 		tbitpos = PADDED(target->size) - tbitpos;
  106: 		REQUIRE(tbitpos >= n);
  107: 		tbitpos -= n;
  108: 	} else
  109: 		REQUIRE(tlast <= target->size);
  110: 
  111: 	if (tlast > target->length)
  112: 		target->length = tlast;
  113: 
  114: 	/*
  115: 	 * This is far from optimal...
  116: 	 */
  117: 
  118: 	while (n > 0) {
  119: 		if (BITSET(source, sbitpos))
  120: 			SETBIT(target, tbitpos);
  121: 		else
  122: 			CLEARBIT(target, tbitpos);
  123: 		sbitpos++;
  124: 		tbitpos++;
  125: 		n--;
  126: 	}
  127: }