Base: Rework the way M5 provides and creates random numbers.

--HG--
extra : convert_revision : 10ec3484647b3acb8e821f8520f97d535e41e861

1 files changed, 149 insertions, 0 deletions

diff --git a/src/base/random_mt.cc b/src/base/random_mt.cc
new file mode 100644
index 000000000..1492240ee
--- /dev/null
+++ b/src/base/random_mt.cc
@@ -0,0 +1,149 @@
+/*
+ * A C-program for MT19937, with initialization improved 2002/1/26.
+ * Coded by Takuji Nishimura and Makoto Matsumoto.
+ *
+ * Before using, initialize the state by using init_genrand(seed)
+ * or init_by_array(init_key, key_length).
+ *
+ * Copyright (C) 1997 - 2002, Makoto Matsumoto and Takuji Nishimura,
+ * All rights reserved.
+ *
+ * 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. The names of its contributors may not 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.
+ *
+ *
+ * Any feedback is very welcome.
+ * http://www.math.sci.hiroshima-u.ac.jp/~m-mat/MT/emt.html
+ * email: m-mat @ math.sci.hiroshima-u.ac.jp (remove space)
+ */
+
+#include "base/random.hh"
+
+/* initializes mt[N] with a seed */
+void
+Random::init(uint32_t s)
+{
+    mti = N + 1;
+    mt[0] = s & (uint32_t)0xffffffff;
+
+    for (mti = 1; mti < N; mti++) {
+        mt[mti] = 1812433253UL * (mt[mti-1] ^ (mt[mti-1] >> 30)) + mti;
+        /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
+        /* In the previous versions, MSBs of the seed affect   */
+        /* only MSBs of the array mt[].                        */
+        /* 2002/01/09 modified by Makoto Matsumoto             */
+        mt[mti] &= (uint32_t)0xffffffff;
+        /* for >32 bit machines */
+    }
+}
+
+/* initialize by an array with array-length */
+/* init_key is the array for initializing keys */
+/* key_length is its length */
+/* slight change for C++, 2004/2/26 */
+void
+Random::init(uint32_t init_key[], int key_length)
+{
+    int i = 1;
+    int j = 0;
+    int k = (N > key_length) ? N : key_length;
+
+    init(19650218);
+
+    for (; k; k--) {
+        mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * (uint32_t)1664525))
+          + init_key[j] + j; /* non linear */
+
+        mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
+
+        i++;
+        j++;
+
+        if (i >= N) {
+            mt[0] = mt[N - 1];
+            i = 1;
+        }
+
+        if (j >= key_length)
+            j = 0;
+    }
+
+    for (k = N - 1; k; k--) {
+        /* non linear */
+        mt[i] = (mt[i] ^ ((mt[i - 1] ^ (mt[i - 1] >> 30)) * 1566083941UL)) - i;
+
+        /* for WORDSIZE > 32 machines */
+        mt[i] &= (uint32_t)0xffffffff;
+        i++;
+
+        if (i >= N) {
+            mt[0] = mt[N - 1];
+            i = 1;
+        }
+    }
+
+    /* MSB is 1; assuring non-zero initial array */
+    mt[0] = (uint32_t)0x80000000;
+}
+
+/* generates a random number on [0,0xffffffff]-interval */
+uint32_t
+Random::genrand()
+{
+    uint32_t y;
+    static uint32_t mag01[2] = { 0, MATRIX_A};
+
+    if (mti >= N) { /* generate N words at one time */
+        int kk;
+
+        for (kk = 0; kk < N - M; kk++) {
+            y = mt[kk] & UPPER_MASK | mt[kk+1] & LOWER_MASK;
+            mt[kk] = mt[kk + M] ^ (y >> 1) ^ mag01[y & 0x1UL];
+        }
+        for (; kk < N - 1; kk++) {
+            y = mt[kk] & UPPER_MASK | mt[kk+1] & LOWER_MASK;
+            mt[kk] = mt[kk + (M - N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
+        }
+
+        y = mt[N - 1] & UPPER_MASK | mt[0] & LOWER_MASK;
+        mt[N - 1] = mt[M - 1] ^ (y >> 1) ^ mag01[y & 0x1UL];
+
+        mti = 0;
+    }
+
+    y = mt[mti++];
+
+    /* Tempering */
+    y ^= (y >> 11);
+    y ^= (y << 7) & (uint32_t)0x9d2c5680;
+    y ^= (y << 15) & (uint32_t)0xefc60000;
+    y ^= (y >> 18);
+
+    return y;
+}