1 files changed, 220 insertions, 0 deletions
diff --git a/nuttx/lib/stdlib/lib_rand.c b/nuttx/lib/stdlib/lib_rand.c
new file mode 100644
index 000000000..537bc1aae
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+++ b/nuttx/lib/stdlib/lib_rand.c
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+/************************************************************
+ * lib/stdlib/lib_rand.c
+ *
+ *   Copyright (C) 2007, 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * 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.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Compilation Switches
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <sys/types.h>
+#include <stdlib.h>
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+#ifndef CONFIG_LIB_RAND_ORDER
+#define CONFIG_LIB_RAND_ORDER 1
+#endif
+
+/* Values needed by the random number generator */
+
+#define RND1_CONSTK  470001
+#define RND1_CONSTP  999563
+#define RND2_CONSTK1 366528
+#define RND2_CONSTK2 508531
+#define RND2_CONSTP  998917
+#define RND3_CONSTK1 360137
+#define RND3_CONSTK2 519815
+#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 Type Declarations
+ ************************************************************/
+
+/************************************************************
+ * Private Function Prototypes
+ ************************************************************/
+
+static unsigned int nrand(unsigned int nLimit);
+static double_t frand1(void);
+#if (CONFIG_LIB_RAND_ORDER > 1)
+static double_t frand2(void);
+#if (CONFIG_LIB_RAND_ORDER > 2)
+static double_t frand3(void);
+#endif
+#endif
+
+/**********************************************************
+ * Global Constant Data
+ **********************************************************/
+
+/************************************************************
+ * Global Variables
+ ************************************************************/
+
+/**********************************************************
+ * Private Constant Data
+ **********************************************************/
+
+/************************************************************
+ * Private Variables
+ ************************************************************/
+
+static unsigned long g_nRandInt1;
+#if (CONFIG_LIB_RAND_ORDER > 1)
+static unsigned long g_nRandInt2;
+#if (CONFIG_LIB_RAND_ORDER > 2)
+static unsigned long g_nRandInt3;
+#endif
+#endif
+
+/************************************************************
+ * Private Functions
+ ************************************************************/
+ 
+static unsigned int nrand(unsigned int nLimit)
+{
+  unsigned long nResult;
+  double_t fRatio;
+
+  /* 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)
+    fRatio = frand1();
+#elif (CONFIG_LIB_RAND_ORDER == 2)
+    fRatio = frand2();
+#else
+    fRatio = frand3();
+#endif
+
+    /* Then, produce the return-able value */
+    nResult = (unsigned long)(((double_t)nLimit) * fRatio);
+
+  } while (nResult >= (unsigned long)nLimit);
+
+  return (unsigned int)nResult;
+
+} /* end nrand */
+
+static double_t frand1(void)
+{
+  unsigned long nRandInt;
+
+  /* First order congruential generator */
+  nRandInt = (RND1_CONSTK * g_nRandInt1) % RND1_CONSTP;
+  g_nRandInt1 = nRandInt;
+
+  /* Construct an floating point value in the range from 0.0 up to 1.0 */
+  return ((double_t)nRandInt) / ((double_t)RND_CONSTP);
+
+} /* end frand */
+
+#if (CONFIG_LIB_RAND_ORDER > 1)
+static double_t frand2(void)
+{
+  unsigned long nRandInt;
+
+  /* Second order congruential generator */
+  nRandInt = (RND2_CONSTK1 * g_nRandInt1 + RND2_CONSTK2 * g_nRandInt2) %
+    RND2_CONSTP;
+  g_nRandInt2 = g_nRandInt1;
+  g_nRandInt1 = nRandInt;
+
+  /* Construct an floating point value in the range from 0.0 up to 1.0 */
+  return ((double_t)nRandInt) / ((double_t)RND_CONSTP);
+
+} /* end frand */
+
+#if (CONFIG_LIB_RAND_ORDER > 2)
+static double_t frand3(void)
+{
+  unsigned long nRandInt;
+
+  /* Third order congruential generator */
+  nRandInt = (RND3_CONSTK1 * g_nRandInt1 + RND3_CONSTK2 * g_nRandInt2 +
+	      RND3_CONSTK2 * g_nRandInt3) % RND3_CONSTP;
+  g_nRandInt3 = g_nRandInt2;
+  g_nRandInt2 = g_nRandInt1;
+  g_nRandInt1 = nRandInt;
+
+  /* Construct an floating point value in the range from 0.0 up to 1.0 */
+  return ((double_t)nRandInt) / ((double_t)RND_CONSTP);
+
+} /* end frand */
+#endif
+#endif
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+/************************************************************
+ * Function:  srand, rand
+ ************************************************************/
+
+void srand(unsigned int seed)
+{
+  g_nRandInt1 = seed;
+#if (CONFIG_LIB_RAND_ORDER > 1)
+  g_nRandInt2 = seed;
+  (void)frand1();
+#if (CONFIG_LIB_RAND_ORDER > 2)
+  g_nRandInt3 = seed;
+  (void)frand2();
+#endif
+#endif
+
+} /* end srand */
+
+int rand(void)
+{
+  return (int)nrand(32768);
+
+} /* end rand */
+