randm.h

《嵌入式网络系统设计-基于Atmel ARM7 系列》这个本书的光盘资料

/*****************************************************************************
* randm.h - Random number generator header file.
*
* Copyright (c) 2003 by Marc Boucher, Services Informatiques (MBSI) inc.
* Copyright (c) 1998 Global Election Systems Inc.
*
* The authors hereby grant permission to use, copy, modify, distribute,
* and license this software and its documentation for any purpose, provided
* that existing copyright notices are retained in all copies and that this
* notice and the following disclaimer are included verbatim in any 
* distributions. No written agreement, license, or royalty fee is required
* for any of the authorized uses.
*
* THIS SOFTWARE IS PROVIDED BY THE CONTRIBUTORS *AS IS* AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 
* IN NO EVENT SHALL THE CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
******************************************************************************
* REVISION HISTORY
*
* 03-01-01 Marc Boucher <[e-mail]>
*   Ported to lwIP.
* 98-05-29 Guy Lancaster <[e-mail]>, Global Election Systems Inc.
*	Extracted from avos.
*****************************************************************************/

#ifndef RANDM_H
#define RANDM_H

/***********************
*** PUBLIC FUNCTIONS ***
***********************/
/*
 * Initialize the random number generator.
 */
void avRandomInit(void);

/*
 * Churn the randomness pool on a random event.  Call this early and often
 *	on random and semi-random system events to build randomness in time for
 *	usage.  For randomly timed events, pass a null pointer and a zero length
 *	and this will use the system timer and other sources to add randomness.
 *	If new random data is available, pass a pointer to that and it will be
 *	included.
 */
void avChurnRand(char *randData, u32_t randLen);

/*
 * Randomize our random seed value.  To be called for truely random events
 * such as user operations and network traffic.
 */
#if MD5_SUPPORT
#define avRandomize()	avChurnRand(NULL, 0)
#else
void avRandomize(void);
#endif

/*
 * Use the random pool to generate random data.  This degrades to pseudo
 *	random when used faster than randomness is supplied using churnRand().
 *	Thus it's important to make sure that the results of this are not
 *	published directly because one could predict the next result to at
 *	least some degree.  Also, it's important to get a good seed before
 *	the first use.
 */
void avGenRand(char *buf, u32_t bufLen);

/*
 * Return a new random number.
 */
u32_t avRandom(void);


#endif /* RANDM_H */