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Diffstat (limited to 'lib/isc/bitstring.c')
| -rw-r--r-- | lib/isc/bitstring.c | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/lib/isc/bitstring.c b/lib/isc/bitstring.c new file mode 100644 index 0000000..33c7c1f --- /dev/null +++ b/lib/isc/bitstring.c @@ -0,0 +1,127 @@ +/* + * 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--; + } +} |