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/dev/random: Add configuration option to use the congruential PRNG.

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This commit is contained in:
Gregory Nutt
2016-07-17 07:56:25 -06:00
parent ffd3a31649
commit 07e20479ad
6 changed files with 193 additions and 42 deletions
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libc/stdlib/Make.defs
+2 -2
View File
@@ -1,7 +1,7 @@
############################################################################
# libc/stdlib/Make.defs
#
# Copyright (C) 2012, 2015 Gregory Nutt. All rights reserved.
# Copyright (C) 2012, 2015-2016 Gregory Nutt. All rights reserved.
# Author: Gregory Nutt <gnutt@nuttx.org>
#
# Redistribution and use in source and binary forms, with or without
@@ -37,7 +37,7 @@
CSRCS += lib_abs.c lib_abort.c lib_div.c lib_ldiv.c lib_lldiv.c
CSRCS += lib_imaxabs.c lib_itoa.c lib_labs.c lib_llabs.c
CSRCS += lib_bsearch.c lib_srand.c lib_qsort.c
CSRCS += lib_bsearch.c lib_rand.c lib_qsort.c lib_srand.c
CSRCS += lib_strtol.c lib_strtoll.c lib_strtoul.c lib_strtoull.c
CSRCS += lib_strtod.c lib_checkbase.c
libc/stdlib/lib_rand.c
+63
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@@ -0,0 +1,63 @@
/****************************************************************************
* libc/stdlib/lib_rand.c
*
* Copyright (C) 2007, 2011, 2016 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 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
* COPYRIGHT OWNER OR 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdlib.h>
#include <nuttx/lib.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: rand
*
* Description:
* Generate a non-negative, integer random number in the range of 0 through
* (RAND_MAX - 1)
*
****************************************************************************/
int rand(void)
{
return (int)nrand(32768L);
}
libc/stdlib/lib_srand.c
+43 -33
View File
@@ -37,12 +37,17 @@
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdlib.h>
#include <nuttx/lib.h>
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* First, second, and thired order congruential generators are supported */
#ifndef CONFIG_LIB_RAND_ORDER
@@ -70,8 +75,6 @@
* Private Function Prototypes
****************************************************************************/
static unsigned int nrand(unsigned int limit);
/* First order congruential generators */
static inline unsigned long fgenerate1(void);
@@ -111,34 +114,6 @@ static unsigned long g_randint3;
* Private Functions
****************************************************************************/
static unsigned int nrand(unsigned int limit)
{
unsigned long result;
double_t ratio;
/* Loop to be sure a legal random number is generated */
do
{
/* Get a random integer in the requested range */
#if (CONFIG_LIB_RAND_ORDER == 1)
ratio = frand1();
#elif (CONFIG_LIB_RAND_ORDER == 2)
ratio = frand2();
#else /* if (CONFIG_LIB_RAND_ORDER > 2) */
ratio = frand3();
#endif
/* Then, produce the return-able value */
result = (unsigned long)(((double_t)limit) * ratio);
}
while (result >= (unsigned long)limit);
return (unsigned int)result;
}
/* First order congruential generators */
static inline unsigned long fgenerate1(void)
@@ -255,7 +230,11 @@ static double_t frand3(void)
****************************************************************************/
/****************************************************************************
* Function: srand, rand
* Name: srand
*
* Description:
* Seed the confluent hypergeometric random number generator.
*
****************************************************************************/
void srand(unsigned int seed)
@@ -271,7 +250,38 @@ void srand(unsigned int seed)
#endif
}
int rand(void)
/****************************************************************************
* Name: nrand
*
* Description:
* Return a random unsigned long value in the range of 0 to (limit - 1)
*
****************************************************************************/
unsigned long nrand(unsigned long limit)
{
return (int)nrand(32768);
unsigned long result;
double_t ratio;
/* Loop to be sure a legal random number is generated */
do
{
/* Get a random integer in the requested range */
#if (CONFIG_LIB_RAND_ORDER == 1)
ratio = frand1();
#elif (CONFIG_LIB_RAND_ORDER == 2)
ratio = frand2();
#else /* if (CONFIG_LIB_RAND_ORDER > 2) */
ratio = frand3();
#endif
/* Then, produce the return-able value */
result = (unsigned long)(((double_t)limit) * ratio);
}
while (result >= limit);
return result;
}