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Diffstat (limited to 'lib/isc/include/isc/bitstring.h')
| -rw-r--r-- | lib/isc/include/isc/bitstring.h | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/lib/isc/include/isc/bitstring.h b/lib/isc/include/isc/bitstring.h new file mode 100644 index 0000000..252d111 --- /dev/null +++ b/lib/isc/include/isc/bitstring.h @@ -0,0 +1,157 @@ +/* + * Copyright (C) 2004-2007 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.h,v 1.14 2007/06/19 23:47:18 tbox Exp $ */ + +#ifndef ISC_BITSTRING_H +#define ISC_BITSTRING_H 1 + +/***** + ***** Module Info + *****/ + +/*! \file isc/bitstring.h + * + * \brief Bitstring manipulation functions. + * + * A bitstring is a packed array of bits, stored in a contiguous + * sequence of octets. The "most significant bit" (msb) of a bitstring + * is the high bit of the first octet. The "least significant bit" of a + * bitstring is the low bit of the last octet. + * + * Two bit numbering schemes are supported, "msb0" and "lsb0". + * + * In the "msb0" scheme, bit number 0 designates the most significant bit, + * and any padding bits required to make the bitstring a multiple of 8 bits + * long are added to the least significant end of the last octet. + * + * In the "lsb0" scheme, bit number 0 designates the least significant bit, + * and any padding bits required to make the bitstring a multiple of 8 bits + * long are added to the most significant end of the first octet. + * + * E.g., consider the bitstring "11010001111". This bitstring is 11 bits + * long and will take two octets. Let "p" denote a pad bit. In the msb0 + * encoding, it would be + * + * \verbatim + * Octet 0 Octet 1 + * | + * 1 1 0 1 0 0 0 1 | 1 1 1 p p p p p + * ^ | ^ + * | | + * bit 0 bit 15 + * \endverbatim + * + * In the lsb0 encoding, it would be + * + * \verbatim + * Octet 0 Octet 1 + * | + * p p p p p 1 1 0 | 1 0 0 0 1 1 1 1 + * ^ | ^ + * | | + * bit 15 bit 0 + * \endverbatim + */ + +/*** + *** Imports + ***/ + +#include <isc/lang.h> +#include <isc/types.h> + +ISC_LANG_BEGINDECLS + +/*** + *** Types + ***/ + +struct isc_bitstring { + unsigned int magic; + unsigned char * data; + unsigned int length; + unsigned int size; + isc_boolean_t lsb0; +}; + +/*** + *** Functions + ***/ + +void +isc_bitstring_init(isc_bitstring_t *bitstring, unsigned char *data, + unsigned int length, unsigned int size, isc_boolean_t lsb0); +/*!< + * \brief 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. + * + * Requires: + * + *\li 'bitstring' points to a isc_bitstring_t. + * + *\li 'data' points to an array of unsigned char large enough to hold + * 'size' bits. + * + *\li 'length' <= 'size'. + * + * Ensures: + * + *\li 'bitstring' is a valid bitstring. + */ + +void +isc_bitstring_invalidate(isc_bitstring_t *bitstring); +/*!< + * \brief Invalidate 'bitstring'. + * + * Requires: + * + *\li 'bitstring' is a valid bitstring. + * + * Ensures: + * + *\li 'bitstring' is not a valid bitstring. + */ + +void +isc_bitstring_copy(isc_bitstring_t *source, unsigned int sbitpos, + isc_bitstring_t *target, unsigned int tbitpos, + unsigned int n); +/*!< + * \brief Starting at bit 'sbitpos', copy 'n' bits from 'source' to + * the 'n' bits of 'target' starting at 'tbitpos'. + * + * Requires: + * + *\li 'source' and target are valid bitstrings with the same lsb0 setting. + * + *\li 'sbitpos' + 'n' is less than or equal to the length of 'source'. + * + *\li 'tbitpos' + 'n' is less than or equal to the size of 'target'. + * + * Ensures: + * + *\li The specified bits have been copied, and the length of 'target' + * adjusted (if required). + */ + +ISC_LANG_ENDDECLS + +#endif /* ISC_BITSTRING_H */ |