ICU-2966 implement portable random number generator

X-SVN-Rev: 12814

icu4c/source/test/intltest/intltest.cpp

@@ -28,6 +28,7 @@
 #include "itmajor.h"
 
 #include "umutex.h"
+#include "uassert.h"
 
 #ifdef XP_MAC_CONSOLE
 #include <console.h>
@@ -1306,6 +1307,50 @@ UnicodeString CharsToUnicodeString(const char* chars)
     return str.unescape();
 }
 
+#define RAND_M  (714025)
+#define RAND_IA (1366)
+#define RAND_IC (150889)
+
+static int32_t RAND_SEED;
+
+/**
+ * Returns a uniform random value x, with 0.0 <= x < 1.0.  Use
+ * with care: Does not return all possible values; returns one of
+ * 714,025 values, uniformly spaced.  However, the period is
+ * effectively infinite.  See: Numerical Recipes, section 7.1.
+ *
+ * @param seedp pointer to seed. Set *seedp to any negative value
+ * to restart the sequence.
+ */
+float IntlTest::random(int32_t* seedp) {
+    static int32_t iy, ir[98];
+    static UBool first=TRUE;
+    int32_t j;
+    if (*seedp < 0 || first) {
+        first = FALSE;
+        if ((*seedp=(RAND_IC-(*seedp)) % RAND_M) < 0) *seedp = -(*seedp);
+        for (j=1;j<=97;++j) {
+            *seedp=(RAND_IA*(*seedp)+RAND_IC) % RAND_M;
+            ir[j]=(*seedp);
+        }
+        *seedp=(RAND_IA*(*seedp)+RAND_IC) % RAND_M;
+        iy=(*seedp);
+    }
+    j=(int32_t)(1 + 97.0*iy/RAND_M);
+    U_ASSERT(j>=1 && j<=97);
+    iy=ir[j];
+    *seedp=(RAND_IA*(*seedp)+RAND_IC) % RAND_M;
+    ir[j]=(*seedp);
+    return (float) iy/RAND_M;
+}
+
+/**
+ * Convenience method using a global seed.
+ */
+float IntlTest::random() {
+    return random(&RAND_SEED);
+}
+
 /*
  * Hey, Emacs, please set the following:
  *

icu4c/source/test/intltest/intltest.h

@@ -119,6 +119,22 @@ public:
 
     FILE *testoutfp;
 
+    /**
+     * Returns a uniform random value x, with 0.0 <= x < 1.0.  Use
+     * with care: Does not return all possible values; returns one of
+     * 714,025 values, uniformly spaced.  However, the period is
+     * effectively infinite.  See: Numerical Recipes, section 7.1.
+     *
+     * @param seedp pointer to seed. Set *seedp to any negative value
+     * to restart the sequence.
+     */
+    static float random(int32_t* seedp);
+
+    /**
+     * Convenience method using a global seed.
+     */
+    static float random();
+
 protected:
     virtual void runIndexedTest( int32_t index, UBool exec, const char* &name, char* par = NULL ); // overide !
 
@@ -143,6 +159,7 @@ private:
     char*       path;           // specifies subtests
 
 protected:
+
     virtual void LL_message( UnicodeString message, UBool newline );
 
     // used for collation result reporting, defined here for convenience