stdlib: generate uniformly distributed pseudo-random numbers

Signed-off-by: dongjiuzhu1 <dongjiuzhu1@xiaomi.com>
This commit is contained in:
Jiuzhu Dong 2021-12-21 22:48:02 +08:00 committed by Xiang Xiao
parent 31134719e7
commit c623ee20f1
3 changed files with 216 additions and 1 deletions

View File

@ -132,6 +132,19 @@ extern "C"
void srand(unsigned int seed); void srand(unsigned int seed);
int rand(void); int rand(void);
void lcong48(FAR unsigned short int param[7]);
FAR unsigned short int *seed48(FAR unsigned short int seed16v[3]);
void srand48(long int seedval);
#ifdef CONFIG_HAVE_LONG_LONG
long int jrand48(FAR unsigned short int xsubi[3]);
long int lrand48(void);
long int mrand48(void);
long int nrand48(FAR unsigned short int xsubi[3]);
# ifdef CONFIG_HAVE_DOUBLE
double drand48(void);
double erand48(FAR unsigned short int xsubi[3]);
# endif
#endif
#define srandom(s) srand(s) #define srandom(s) srand(s)
long random(void); long random(void);

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@ -23,7 +23,7 @@
CSRCS += lib_abs.c lib_abort.c lib_atof.c lib_atoi.c lib_getprogname.c CSRCS += lib_abs.c lib_abort.c lib_atof.c lib_atoi.c lib_getprogname.c
CSRCS += lib_atol.c lib_atoll.c lib_div.c lib_ldiv.c lib_lldiv.c lib_exit.c CSRCS += lib_atol.c lib_atoll.c lib_div.c lib_ldiv.c lib_lldiv.c lib_exit.c
CSRCS += lib_itoa.c lib_labs.c lib_llabs.c lib_realpath.c lib_bsearch.c CSRCS += lib_itoa.c lib_labs.c lib_llabs.c lib_realpath.c lib_bsearch.c
CSRCS += lib_rand.c lib_qsort.c lib_srand.c lib_strtol.c CSRCS += lib_rand.c lib_rand48.c lib_qsort.c lib_srand.c lib_strtol.c
CSRCS += lib_strtoll.c lib_strtoul.c lib_strtoull.c lib_strtod.c lib_strtof.c CSRCS += lib_strtoll.c lib_strtoul.c lib_strtoull.c lib_strtod.c lib_strtof.c
CSRCS += lib_strtold.c lib_checkbase.c lib_mktemp.c lib_mkstemp.c lib_mkdtemp.c CSRCS += lib_strtold.c lib_checkbase.c lib_mktemp.c lib_mkstemp.c lib_mkdtemp.c
CSRCS += lib_aligned_alloc.c lib_posix_memalign.c lib_valloc.c lib_mblen.c CSRCS += lib_aligned_alloc.c lib_posix_memalign.c lib_valloc.c lib_mblen.c

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@ -0,0 +1,202 @@
/****************************************************************************
* libs/libc/stdlib/lib_rand48.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <stdlib.h>
#include <nuttx/lib/lib.h>
/****************************************************************************
* Private Data
****************************************************************************/
static unsigned short int g_seed48[7] =
{
0,
0,
0,
0xe66d,
0xdeec,
0x5,
0xb
};
/****************************************************************************
* Private Functions
****************************************************************************/
#ifdef CONFIG_HAVE_LONG_LONG
static uint64_t rand48_step(FAR unsigned short int *xi,
FAR unsigned short int *lc)
{
uint64_t a;
uint64_t x;
x = xi[0] | ((xi[1] + 0ul) << 16) | ((xi[2] + 0ull) << 32);
a = lc[0] | ((lc[1] + 0ul) << 16) | ((lc[2] + 0ull) << 32);
x = a * x + lc[3];
xi[0] = x;
xi[1] = x >> 16;
xi[2] = x >> 32;
return x & 0xffffffffffffull;
}
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: srand48
****************************************************************************/
void srand48(long seed)
{
unsigned short int p[3];
p[0] = 0x330e;
p[1] = seed;
p[2] = seed >> 16;
seed48(p);
}
/****************************************************************************
* Name: seed48
****************************************************************************/
FAR unsigned short int *seed48(FAR unsigned short int seed16v[3])
{
static unsigned short int p[3];
memcpy(p, g_seed48, sizeof(p));
memcpy(g_seed48, seed16v, sizeof(p));
return p;
}
/****************************************************************************
* Name: lcong48
****************************************************************************/
void lcong48(FAR unsigned short int p[7])
{
memcpy(g_seed48, p, sizeof(g_seed48));
}
/****************************************************************************
* Name: jrand48
*
* Description:
* Return signed long integers uniformly distributed over the
* interval [-2^31, 2^31).
*
****************************************************************************/
#ifdef CONFIG_HAVE_LONG_LONG
long jrand48(FAR unsigned short int s[3])
{
return (long)(rand48_step(s, g_seed48 + 3) >> 16);
}
/****************************************************************************
* Name: mrand48
*
* Description:
* Return signed long integers uniformly distributed over the
* interval [-2^31, 2^31).
*
****************************************************************************/
long mrand48(void)
{
return jrand48(g_seed48);
}
/****************************************************************************
* Name: nrand48
*
* Description:
* Return nonnegative long integers uniformly distributed over the
* interval [0, 2^31).
*
****************************************************************************/
long nrand48(FAR unsigned short int s[3])
{
return rand48_step(s, g_seed48 + 3) >> 17;
}
/****************************************************************************
* Name: lrand48
*
* Description:
* Return nonnegative long integers uniformly distributed over the
* interval [0, 2^31).
*
****************************************************************************/
long lrand48(void)
{
return nrand48(g_seed48);
}
/****************************************************************************
* Name: erand48
*
* Description:
* Return nonnegative double-precision floating-point values uniformly
* distributed over the interval [0.0, 1.0).
*
****************************************************************************/
# ifdef CONFIG_HAVE_DOUBLE
double erand48(FAR unsigned short int s[3])
{
union
{
uint64_t u;
double f;
} x;
x.u = 0x3ff0000000000000ull | rand48_step(s, g_seed48 + 3) << 4;
return x.f - 1.0;
}
/****************************************************************************
* Name: drand48
*
* Description:
* Return nonnegative double-precision floating-point values uniformly
* distributed over the interval [0.0, 1.0).
*
****************************************************************************/
double drand48(void)
{
return erand48(g_seed48);
}
# endif
#endif