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+/****************************************************************************
+ * examples/random/random_main.c
+ *
+ * Copyright (C) 2013 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 <stdio.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <debug.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+/* Configuration ************************************************************/
+
+#ifndef CONFIG_EXAMPLES_MAXSAMPLES
+# define CONFIG_EXAMPLES_MAXSAMPLES 64
+#endif
+
+#ifndef CONFIG_EXAMPLES_NSAMPLES
+# define CONFIG_EXAMPLES_NSAMPLES 8
+#endif
+
+#if CONFIG_EXAMPLES_NSAMPLES > CONFIG_EXAMPLES_MAXSAMPLES
+# warning CONFIG_EXAMPLES_NSAMPLES > CONFIG_EXAMPLES_MAXSAMPLES
+# undef CONFIG_EXAMPLES_NSAMPLES
+# define CONFIG_EXAMPLES_NSAMPLES CONFIG_EXAMPLES_MAXSAMPLES
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * rand_main
+ ****************************************************************************/
+
+int rand_main(int argc, char *argv[])
+{
+ uint32_t buffer[CONFIG_EXAMPLES_MAXSAMPLES];
+ int nsamples = CONFIG_EXAMPLES_NSAMPLES;
+ ssize_t nread;
+ int fd;
+
+ /* One argument is possible... the number of samples to collect */
+
+ if (argc > 1)
+ {
+ nsamples = atoi(argv[1]);
+ }
+
+ /* Clip the numer of samples to the configured buffer size */
+
+ if (nsamples > CONFIG_EXAMPLES_MAXSAMPLES)
+ {
+ nsamples = CONFIG_EXAMPLES_MAXSAMPLES;
+ }
+
+ /* Open /dev/random */
+
+ fd = open("/dev/random", O_RDONLY);
+ if (fd < 0)
+ {
+ int errcode = errno;
+ fprintf(stderr, "ERROR: Failed to open /dev/random: %d\n", errcode);
+ exit(EXIT_FAILURE);
+ }
+
+ /* Read the requested number of samples */
+
+ printf("Reading %d random numbers\n", nsamples);
+ nread = read(fd, buffer, nsamples * sizeof(uint32_t));
+ if (nread < 0)
+ {
+ int errcode = errno;
+ fprintf(stderr, "ERROR: Read from /dev/randon failed: %d\n", errcode);
+ (void)close(fd);
+ exit(EXIT_FAILURE);
+ }
+
+ /* Dump the sample buffer */
+
+ lib_dumpbuffer("Random values", (FAR const uint8_t*)buffer, nread);
+ (void)close(fd);
+ return EXIT_SUCCESS;
+}
+