From 7e52ddb904f45c1f621c83231fe2c6cb2a84d6ad Mon Sep 17 00:00:00 2001
From: Tylo <tylo@norceresearch.no>
Date: Wed, 27 May 2020 22:54:18 +0200
Subject: Removed comments, cleanup.

---
 rngtest.c     | 81 +++--------------------------------------------------------
 stc/crandom.h | 78 +++++++++++++-------------------------------------------
 2 files changed, 21 insertions(+), 138 deletions(-)

diff --git a/rngtest.c b/rngtest.c
index 8987ff5d..b24caaa9 100644
--- a/rngtest.c
+++ b/rngtest.c
@@ -7,73 +7,6 @@
 #endif
 
 
-
-/* Period parameters */  
-#define N 624
-#define M 397
-#define MATRIX_A 0x9908b0dfUL   /* constant vector a */
-#define UPPER_MASK 0x80000000UL /* most significant w-r bits */
-#define LOWER_MASK 0x7fffffffUL /* least significant r bits */
-
-static unsigned long mt[N]; /* the array for the state vector  */
-static int mti=N+1; /* mti==N+1 means mt[N] is not initialized */
-
-/* initializes mt[N] with a seed */
-void init_genrand(unsigned long s)
-{
-    mt[0]= s & 0xffffffffUL;
-    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] &= 0xffffffffUL;
-        /* for >32 bit machines */
-    }
-}
-
-/* generates a random number on [0,0xffffffff]-interval */
-unsigned long genrand_int32(void)
-{
-    unsigned long y;
-    static unsigned long mag01[2]={0x0UL, MATRIX_A};
-    /* mag01[x] = x * MATRIX_A  for x=0,1 */
-
-    if (mti >= N) { /* generate N words at one time */
-        int kk;
-
-        if (mti == N+1)   /* if init_genrand() has not been called, */
-            init_genrand(5489UL); /* a default initial seed is used */
-
-        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) & 0x9d2c5680UL;
-    y ^= (y << 15) & 0xefc60000UL;
-    y ^= (y >> 18);
-
-    return y;
-}
-
-
-
 #define NN 1000000000
 
 int main(void)
@@ -82,15 +15,6 @@ int main(void)
     uint64_t v;
     printf("start\n");
 
-    before = clock(); \
-    v = 0;
-    for (size_t i=0; i<NN; i++) {
-        v += genrand_int32();
-    }
-    difference = clock() - before;
-    printf("refmt: %.02f, %llu\n", (float) difference / CLOCKS_PER_SEC, v);
-
-
     mt19937_t state = mt19937_default();
 
     before = clock(); \
@@ -99,7 +23,7 @@ int main(void)
         v += mt19937_rand(&state);
     }
     difference = clock() - before;
-    printf("mymt : %.02f, %llu\n", (float) difference / CLOCKS_PER_SEC, v);
+    printf("my-mt: %.02f, %llu\n", (float) difference / CLOCKS_PER_SEC, v);
 
 #ifdef __cplusplus
     std::mt19937 mt_rand;
@@ -131,7 +55,7 @@ int main(void)
     difference = clock() - before;
     printf("sfc64: %.02f, %llu\n", (float) difference / CLOCKS_PER_SEC, v);
 
-
+/*
     before = clock(); \
     v = 0;
     for (size_t i=0; i<NN; i++) {
@@ -139,4 +63,5 @@ int main(void)
     }
     difference = clock() - before;
     printf("rand : %.02f, %llu\n", (float) difference / CLOCKS_PER_SEC, v);
+*/
 }
\ No newline at end of file
diff --git a/stc/crandom.h b/stc/crandom.h
index 064c86eb..2bf88028 100644
--- a/stc/crandom.h
+++ b/stc/crandom.h
@@ -1,75 +1,32 @@
 #ifndef CRANDOM__H__
 #define CRANDOM__H__
-/*
-     Mersenne Twister random number generator MT19937, 32 bit.
-     A C-program for MT19937, with initialization improved 2002/1/26.
-     Coded by Takuji Nishimura and Makoto Matsumoto.
-     Optimized by Tyge Løvset.
-
-     Before using, initialize the state by using mt19937_init(),
-     mt19937_seed() or mt19937_default().
-
-     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 <stdint.h>
 
-enum { /* period parameters */
+/*
+ * Mersenne Twister random number generator MT19937, 32 bit.
+ */
+
+enum {
     mt19937_N = 624,
     mt19937_M = 397,
 };
 
 typedef struct mt19937 {
-    uint_fast32_t idx;
-    uint_fast32_t arr[mt19937_N]; /* the array for the state vector */
+    uint32_t idx;
+    uint32_t arr[mt19937_N];
 } mt19937_t;
 
 /* initializes state with a seed */
-static inline void mt19937_init(mt19937_t *state, uint_fast32_t seed) {
+static inline void mt19937_init(mt19937_t *state, uint32_t seed) {
     state->idx = mt19937_N;
     state->arr[0] = seed;
     for (int i = 1; i < mt19937_N; ++i) {
         seed = state->arr[i] = 1812433253 * (seed ^ (seed >> 30)) + i; 
-        /* See Knuth TAOCP Vol2. 3rd Ed. P.106 for multiplier. */
-        /* In the previous versions, MSBs of the seed affect   */
-        /* only MSBs of the array arr[].                       */
-        /* 2002/01/09 modified by Makoto Matsumoto             */
     }
 }
 /* creates a new state from a seed */
-static inline mt19937_t mt19937_seed(uint_fast32_t seed) {
+static inline mt19937_t mt19937_seed(uint32_t seed) {
     mt19937_t state;
     mt19937_init(&state, seed);
     return state;
@@ -82,10 +39,10 @@ static inline mt19937_t mt19937_default(void) {
 }
 
 /* generates a random number on [0, 0xffffffff]-interval */
-static inline uint_fast32_t mt19937_rand(mt19937_t *state) {
+static inline uint32_t mt19937_rand(mt19937_t *state) {
     enum {N = mt19937_N, M = mt19937_M};
 
-    uint_fast32_t y, *arr = state->arr;
+    uint32_t y, *arr = state->arr;
     if (state->idx >= N) { /* generate N words at one time */
         int k = 0;
         for (; k < N-M; ++k) {
@@ -110,7 +67,9 @@ static inline uint_fast32_t mt19937_rand(mt19937_t *state) {
     return y;
 }
 
-/* xoroshiro128** and xoshiro128** with splitmix64 seed initialization */
+/* 
+ * xoroshiro128** with splitmix64 seed initialization
+ */
 
 static inline uint64_t splitmix64(uint64_t *state) {
     uint64_t z = (*state += 0x9e3779b97f4a7c15);
@@ -123,8 +82,6 @@ static inline uint64_t c_rotl(uint64_t x, int s) {
     return (x << s) | (x >> (64 - s));
 }
 
-/* xoroshiro128** */
-
 typedef struct xoroshiro128ss {
     uint64_t s[2];
 } xoroshiro128ss_t;
@@ -146,13 +103,14 @@ static inline uint64_t xoroshiro128ss_rand(xoroshiro128ss_t *state) {
     return result;
 }
 
-/* http://pracrand.sourceforge.net */
+/*
+ * sfc64: http://pracrand.sourceforge.net
+ */
 
 typedef struct sfc64 {
     uint64_t s[3], counter;
 } sfc64_t;
 
-
 static inline uint64_t sfc64_rand(sfc64_t* state) {
     enum {LROT = 24, RSHIFT = 11, LSHIFT = 3};
     uint64_t *s = state->s;
@@ -160,7 +118,7 @@ static inline uint64_t sfc64_rand(sfc64_t* state) {
     uint64_t result = s[0] + s[1] + ++state->counter;
     s[0] = s[1] ^ (s[1] >> RSHIFT);
     s[1] = s[2] + (s[2] << LSHIFT);
-    s[2] = ((s[2] << LROT) | (s[2] >> (64-LROT))) + result;
+    s[2] = c_rotl(s[2], LROT) + result;
     return result;
 }
 
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