--- /dev/null
+/* xf86drmRandom.c -- "Minimal Standard" PRNG Implementation
+ * Created: Mon Apr 19 08:28:13 1999 by faith@precisioninsight.com
+ *
+ * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
+ * 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:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * 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
+ * PRECISION INSIGHT AND/OR ITS SUPPLIERS 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.
+ *
+ * Authors: Rickard E. (Rik) Faith <faith@valinux.com>
+ *
+ * DESCRIPTION
+ *
+ * This file contains a simple, straightforward implementation of the Park
+ * & Miller "Minimal Standard" PRNG [PM88, PMS93], which is a Lehmer
+ * multiplicative linear congruential generator (MLCG) with a period of
+ * 2^31-1.
+ *
+ * This implementation is intended to provide a reliable, portable PRNG
+ * that is suitable for testing a hash table implementation and for
+ * implementing skip lists.
+ *
+ * FUTURE ENHANCEMENTS
+ *
+ * If initial seeds are not selected randomly, two instances of the PRNG
+ * can be correlated. [Knuth81, pp. 32-33] describes a shuffling technique
+ * that can eliminate this problem.
+ *
+ * If PRNGs are used for simulation, the period of the current
+ * implementation may be too short. [LE88] discusses methods of combining
+ * MLCGs to produce much longer periods, and suggests some alternative
+ * values for A and M. [LE90 and Sch92] also provide information on
+ * long-period PRNGs.
+ *
+ * REFERENCES
+ *
+ * [Knuth81] Donald E. Knuth. The Art of Computer Programming. Volume 2:
+ * Seminumerical Algorithms. Reading, Massachusetts: Addison-Wesley, 1981.
+ *
+ * [LE88] Pierre L'Ecuyer. "Efficient and Portable Combined Random Number
+ * Generators". CACM 31(6), June 1988, pp. 742-774.
+ *
+ * [LE90] Pierre L'Ecuyer. "Random Numbers for Simulation". CACM 33(10,
+ * October 1990, pp. 85-97.
+ *
+ * [PM88] Stephen K. Park and Keith W. Miller. "Random Number Generators:
+ * Good Ones are Hard to Find". CACM 31(10), October 1988, pp. 1192-1201.
+ *
+ * [Sch92] Bruce Schneier. "Pseudo-Ransom Sequence Generator for 32-Bit
+ * CPUs". Dr. Dobb's Journal 17(2), February 1992, pp. 34, 37-38, 40.
+ *
+ * [PMS93] Stephen K. Park, Keith W. Miller, and Paul K. Stockmeyer. In
+ * "Technical Correspondence: Remarks on Choosing and Implementing Random
+ * Number Generators". CACM 36(7), July 1993, pp. 105-110.
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "xf86drm.h"
+#include "xf86drmRandom.h"
+
+static void check_period(unsigned long seed)
+{
+ unsigned long count = 0;
+ unsigned long initial;
+ void *state;
+
+ state = drmRandomCreate(seed);
+ initial = drmRandom(state);
+ ++count;
+ while (initial != drmRandom(state)) {
+ if (!++count) break;
+ }
+ printf("With seed of %10lu, period = %10lu (0x%08lx)\n",
+ seed, count, count);
+ drmRandomDestroy(state);
+}
+
+int main(void)
+{
+ RandomState *state;
+ int i;
+ unsigned long rand;
+
+ state = drmRandomCreate(1);
+ for (i = 0; i < 10000; i++) {
+ rand = drmRandom(state);
+ }
+ printf("After 10000 iterations: %lu (%lu expected): %s\n",
+ rand, state->check,
+ rand - state->check ? "*INCORRECT*" : "CORRECT");
+ drmRandomDestroy(state);
+
+ printf("Checking periods...\n");
+ check_period(1);
+ check_period(2);
+ check_period(31415926);
+
+ return 0;
+}
#include <stdio.h>
#include <stdlib.h>
-#define RANDOM_MAIN 0
-
-#if !RANDOM_MAIN
-# include "xf86drm.h"
-#endif
+#include "xf86drm.h"
+#include "xf86drmRandom.h"
#define RANDOM_MAGIC 0xfeedbeef
#define RANDOM_DEBUG 0
-#if RANDOM_MAIN
-#define RANDOM_ALLOC malloc
-#define RANDOM_FREE free
-#else
-#define RANDOM_ALLOC drmMalloc
-#define RANDOM_FREE drmFree
-#endif
-
-typedef struct RandomState {
- unsigned long magic;
- unsigned long a;
- unsigned long m;
- unsigned long q; /* m div a */
- unsigned long r; /* m mod a */
- unsigned long check;
- unsigned long seed;
-} RandomState;
-
-#if RANDOM_MAIN
-extern void *drmRandomCreate(unsigned long seed);
-extern int drmRandomDestroy(void *state);
-extern unsigned long drmRandom(void *state);
-extern double drmRandomDouble(void *state);
-#endif
-
void *drmRandomCreate(unsigned long seed)
{
RandomState *state;
- state = RANDOM_ALLOC(sizeof(*state));
+ state = drmMalloc(sizeof(*state));
if (!state) return NULL;
state->magic = RANDOM_MAGIC;
#if 0
int drmRandomDestroy(void *state)
{
- RANDOM_FREE(state);
+ drmFree(state);
return 0;
}
return (double)drmRandom(state)/(double)s->m;
}
-
-#if RANDOM_MAIN
-static void check_period(unsigned long seed)
-{
- unsigned long count = 0;
- unsigned long initial;
- void *state;
-
- state = drmRandomCreate(seed);
- initial = drmRandom(state);
- ++count;
- while (initial != drmRandom(state)) {
- if (!++count) break;
- }
- printf("With seed of %10lu, period = %10lu (0x%08lx)\n",
- seed, count, count);
- drmRandomDestroy(state);
-}
-
-int main(void)
-{
- RandomState *state;
- int i;
- unsigned long rand;
-
- state = drmRandomCreate(1);
- for (i = 0; i < 10000; i++) {
- rand = drmRandom(state);
- }
- printf("After 10000 iterations: %lu (%lu expected): %s\n",
- rand, state->check,
- rand - state->check ? "*INCORRECT*" : "CORRECT");
- drmRandomDestroy(state);
-
- printf("Checking periods...\n");
- check_period(1);
- check_period(2);
- check_period(31415926);
-
- return 0;
-}
-#endif
--- /dev/null
+/*
+ * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
+ * 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:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * 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
+ * PRECISION INSIGHT AND/OR ITS SUPPLIERS 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.
+ *
+ * Authors: Rickard E. (Rik) Faith <faith@valinux.com>
+ */
+
+typedef struct RandomState {
+ unsigned long magic;
+ unsigned long a;
+ unsigned long m;
+ unsigned long q; /* m div a */
+ unsigned long r; /* m mod a */
+ unsigned long check;
+ unsigned long seed;
+} RandomState;
projects / platform / upstream / libdrm.git / commitdiff