/contrib/bind9/lib/isc/include/isc/bitstring.h
https://bitbucket.org/freebsd/freebsd-head/ · C++ Header · 157 lines · 23 code · 15 blank · 119 comment · 0 complexity · 47be3c40230b741d5ea7a15fce3c6172 MD5 · raw file
- /*
- * 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 */