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+/*---------------------------------------------------------------
+ * Copyright (c) 2017
+ * Broadcom Corporation
+ * All Rights Reserved.
+ *---------------------------------------------------------------
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated
+ * documentation files (the "Software"), to deal in the Software
+ * without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute,
+ * sublicense, and/or sell copies of the Software, and to permit
+ * persons to whom the Software is furnished to do
+ * so, subject to the following conditions:
+ *
+ *
+ * Redistributions of source code must retain the above
+ * copyright notice, this list of conditions and
+ * the following disclaimers.
+ *
+ *
+ * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following
+ * disclaimers in the documentation and/or other materials
+ * provided with the distribution.
+ *
+ *
+ * Neither the name of Broadcom Coporation,
+ * nor the names of its contributors may be used to endorse
+ * or promote products derived from this Software without
+ * specific prior written permission.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE CONTIBUTORS OR COPYRIGHT
+ * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ * ________________________________________________________________
+ *
+ * pdfs.c
+ * Produce probability distribution functions, expected to be used
+ * for iperf client traffic emulations
+ *
+ * Implements the Polar form of the Box-Muller Transformation
+ *
+ * by Robert J. McMahon (rjmcmahon@rjmcmahon.com, bob.mcmahon@broadcom.com)
+ * & Tim Auckland
+ * -------------------------------------------------------------------
+ */
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <math.h>
+#include "headers.h"
+#include "pdfs.h"
+
+#define FALSE 0
+#define TRUE 1
+float box_muller(void) {
+    float x1, x2, w, y1;
+    static float y2;
+    static int generate = FALSE;
+    /* Each iteration produces two values, if one exists use the value from previous call */
+    generate = !generate;
+    if (!generate) {
+	y1 = y2;
+    } else {
+	int loopcontrol=100;
+	do {
+	    x1 = 2.0 * (float)rand()/(float)(RAND_MAX) - 1.0;
+	    x2 = 2.0 * (float)rand()/(float)(RAND_MAX) - 1.0;
+	    w = x1 * x1 + x2 * x2;
+	} while ( w >= 1.0 && --loopcontrol > 0);
+	if (w >= 1.0) {
+	    fprintf(stderr, "pdf box_muller() rand() error\n");
+	    return 0;
+	} else {
+	    w = sqrt( (-2.0 * logf( w ) ) / w );
+	    y1 = x1 * w;
+	    y2 = x2 * w;
+	}
+    }
+    return(y1);
+}
+
+float normal(float mean, float variance) {
+    return (box_muller() * variance + mean);
+}
+
+float lognormal(float mu, float sigma) {
+    float phi = sqrtf((mu * mu) + (sigma * sigma));
+    float mu_prime = logf(((mu * mu)/phi));
+    float sigma_prime = sqrtf(logf((phi * phi)/(mu * mu)));
+    return (expf(normal(mu_prime,sigma_prime)));
+}