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Correct some errors in lib_rand.c from last check-in

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git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5405 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2012-12-01 18:04:10 +00:00
parent 929ffc14d2
commit 131684fb54
2 changed files with 77 additions and 36 deletions
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8
configs/sim/nx11/defconfig
View File

@ -319,11 +319,3 @@ CONFIG_PTHREAD_STACK_MIN=256
CONFIG_PTHREAD_STACK_DEFAULT=8192
CONFIG_HEAP_BASE=
CONFIG_HEAP_SIZE=
#
# Maintain legacy build behavior (revisit)
#
CONFIG_MMCSD=y
CONFIG_MMCSD_SPI=y
CONFIG_MMCSD_SDIO=y

105
libc/stdlib/lib_rand.c
View File

@ -43,11 +43,17 @@
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/* First, second, and thired order congruential generators are supported */
#ifndef CONFIG_LIB_RAND_ORDER
# define CONFIG_LIB_RAND_ORDER 1
#endif
#if CONFIG_LIB_RAND_ORDER > 3
# undef CONFIG_LIB_RAND_ORDER
# define CONFIG_LIB_RAND_ORDER 3
#endif
/* Values needed by the random number generator */
#define RND1_CONSTK 470001
@ -60,23 +66,31 @@
#define RND3_CONSTK3 616087
#define RND3_CONSTP 997783
#if CONFIG_LIB_RAND_ORDER == 1
# define RND_CONSTP RND1_CONSTP
#elif CONFIG_LIB_RAND_ORDER == 2
# define RND_CONSTP RND2_CONSTP
#else
# define RND_CONSTP RND3_CONSTP
#endif
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
static unsigned int nrand(unsigned int nLimit);
/* First order congruential generators */
static inline void fgenerate1(void);
#if (CONFIG_LIB_RAND_ORDER == 1)
static double_t frand1(void);
#endif
/* Second order congruential generators */
#if (CONFIG_LIB_RAND_ORDER > 1)
static inline void fgenerate2(void);
#if (CONFIG_LIB_RAND_ORDER == 2)
static double_t frand2(void);
#endif
/* Third order congruential generators */
#if (CONFIG_LIB_RAND_ORDER > 2)
static inline void fgenerate3(void);
static double_t frand3(void);
#endif
#endif
@ -112,7 +126,7 @@ static unsigned int nrand(unsigned int nLimit)
ratio = frand1();
#elif (CONFIG_LIB_RAND_ORDER == 2)
ratio = frand2();
#else
#else /* if (CONFIG_LIB_RAND_ORDER > 2) */
ratio = frand3();
#endif
@ -125,50 +139,78 @@ static unsigned int nrand(unsigned int nLimit)
return (unsigned int)result;
}
static double_t frand1(void)
/* First order congruential generators */
static inline void fgenerate1(void)
{
unsigned long randint;
/* First order congruential generator. One is added to the result of the
* generated value to avoid the value zero which breaks the logic.
/* First order congruential generator. One may be added to the result of the
* generated value to avoid the value zero. This would be fatal for the
* first order random number generator.
*/
randint = (RND1_CONSTK * g_randint1) % RND1_CONSTP + 1;
g_randint1 = randint;
randint = (RND1_CONSTK * g_randint1) % RND1_CONSTP;
g_randint1 = (randint == 0 ? 1 : randint);
}
#if (CONFIG_LIB_RAND_ORDER == 1)
static double_t frand1(void)
{
/* First order congruential generator. */
fgenerate1();
/* Construct an floating point value in the range from 0.0 up to 1.0 */
return ((double_t)randint) / ((double_t)RND_CONSTP);
return ((double_t)g_randint1) / ((double_t)RND1_CONSTP);
}
#endif
/* Second order congruential generators */
#if (CONFIG_LIB_RAND_ORDER > 1)
static double_t frand2(void)
static inline void fgenerate2(void)
{
unsigned long randint;
/* Second order congruential generator. One is added to the result of the
* generated value to avoid the value zero which breaks the logic.
/* Second order congruential generator. One may be added to the result of the
* generated value to avoid the value zero (I am not sure if this is necessor
* for higher order random number generators or how this may effect the quality
* of the generated numbers).
*/
randint = (RND2_CONSTK1 * g_randint1 +
RND2_CONSTK2 * g_randint2) % RND2_CONSTP + 1;
g_randint2 = g_randint1;
g_randint1 = randint;
g_randint1 = (randint == 0 ? 1 : randint);
}
#if (CONFIG_LIB_RAND_ORDER == 2)
static double_t frand2(void)
{
/* Second order congruential generator */
fgenerate2();
/* Construct an floating point value in the range from 0.0 up to 1.0 */
return ((double_t)randint) / ((double_t)RND_CONSTP);
return ((double_t)g_randint1) / ((double_t)RND2_CONSTP);
}
#endif
/* Third order congruential generators */
#if (CONFIG_LIB_RAND_ORDER > 2)
static double_t frand3(void)
static inline void fgenerate3(void)
{
unsigned long randint;
/* Third order congruential generator. One is added to the result of the
* generated value to avoid the value zero which breaks the logic.
/* Third order congruential generator. One may be added to the result of the
* generated value to avoid the value zero (I am not sure if this is necessor
* for higher order random number generators or how this may effect the quality
* of the generated numbers).
*/
randint = (RND3_CONSTK1 * g_randint1 +
@ -177,11 +219,18 @@ static double_t frand3(void)
g_randint3 = g_randint2;
g_randint2 = g_randint1;
g_randint1 = randint;
g_randint1 = (randint == 0 ? 1 : randint);
}
static double_t frand3(void)
{
/* Third order congruential generator */
fgenerate3();
/* Construct an floating point value in the range from 0.0 up to 1.0 */
return ((double_t)randint) / ((double_t)RND_CONSTP);
return ((double_t)g_randint1) / ((double_t)RND3_CONSTP);
}
#endif
#endif
@ -199,10 +248,10 @@ void srand(unsigned int seed)
g_randint1 = seed;
#if (CONFIG_LIB_RAND_ORDER > 1)
g_randint2 = seed;
(void)frand1();
fgenerate1();
#if (CONFIG_LIB_RAND_ORDER > 2)
g_randint3 = seed;
(void)frand2();
fgenerate2();
#endif
#endif
}