Switch random generator from Mersenne Twister to Xorshit128.

Now `rand` can be used with `MRB_WITHOUT_FLOAT`; ref #4576

3 files changed, 108 insertions, 422 deletions

diff --git a/mrbgems/mruby-random/src/mt19937ar.c b/mrbgems/mruby-random/src/mt19937ar.c
deleted file mode 100644
index 405bd5c20..000000000
--- a/mrbgems/mruby-random/src/mt19937ar.c
+++ /dev/null
@@ -1,224 +0,0 @@
-/*
-** mt19937ar.c - MT Random functions
-**
-** Copyright (C) 1997 - 2016, Makoto Matsumoto and Takuji Nishimura,
-** 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 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 THE AUTHORS 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.
-**
-** [ MIT license: http://www.opensource.org/licenses/mit-license.php ]
-**
-** 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)
-**
-** This version is modified by mruby developers. If you see any problem,
-** contact us first at https://github.com/mruby/mruby/issues
-*/
-
-#include <mruby.h>
-#include "mt19937ar.h"
-
-/* 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 */
-
-#if 0 /* dead_code */
-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 */
-#endif /* dead_code */
-
-void mrb_random_init_genrand(mt_state *t, unsigned long s)
-{
-    t->mt[0]= s & 0xffffffffUL;
-    for (t->mti=1; t->mti<N; t->mti++) {
-        t->mt[t->mti] = (1812433253UL * (t->mt[t->mti-1] ^ (t->mt[t->mti-1] >> 30)) + t->mti);
-        t->mt[t->mti] &= 0xffffffffUL;
-    }
-}
-
-unsigned long mrb_random_genrand_int32(mt_state *t)
-{
-    unsigned long y;
-    static const unsigned long mag01[2]={0x0UL, MATRIX_A};
-    /* mag01[x] = x * MATRIX_A  for x=0,1 */
-
-    if (t->mti >= N) { /* generate N words at one time */
-        int kk;
-
-        if (t->mti == N+1)   /* if init_genrand() has not been called, */
-            mrb_random_init_genrand(t, 5489UL); /* a default initial seed is used */
-
-        for (kk=0;kk<N-M;kk++) {
-            y = (t->mt[kk]&UPPER_MASK)|(t->mt[kk+1]&LOWER_MASK);
-            t->mt[kk] = t->mt[kk+M] ^ (y >> 1) ^ mag01[y & 0x1UL];
-        }
-        for (;kk<N-1;kk++) {
-            y = (t->mt[kk]&UPPER_MASK)|(t->mt[kk+1]&LOWER_MASK);
-            t->mt[kk] = t->mt[kk+(M-N)] ^ (y >> 1) ^ mag01[y & 0x1UL];
-        }
-        y = (t->mt[N-1]&UPPER_MASK)|(t->mt[0]&LOWER_MASK);
-        t->mt[N-1] = t->mt[M-1] ^ (y >> 1) ^ mag01[y & 0x1UL];
-
-        t->mti = 0;
-    }
-
-    y = t->mt[t->mti++];
-
-    /* Tempering */
-    y ^= (y >> 11);
-    y ^= (y << 7) & 0x9d2c5680UL;
-    y ^= (y << 15) & 0xefc60000UL;
-    y ^= (y >> 18);
-
-    t->gen.int_ = y;
-
-    return y;
-}
-
-double mrb_random_genrand_real1(mt_state *t)
-{
-    mrb_random_genrand_int32(t);
-    t->gen.double_ =  t->gen.int_*(1.0/4294967295.0);
-    return t->gen.double_;
-    /* divided by 2^32-1 */
-}
-
-#if 0 /* dead_code */
-/* 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 */
-    }
-}
-
-/* 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 init_by_array(unsigned long init_key[], int key_length)
-{
-    int i, j, k;
-    init_genrand(19650218UL);
-    i=1; j=0;
-    k = (N>key_length ? N : key_length);
-    for (; k; k--) {
-        mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1664525UL))
-          + 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--) {
-        mt[i] = (mt[i] ^ ((mt[i-1] ^ (mt[i-1] >> 30)) * 1566083941UL))
-          - i; /* non linear */
-        mt[i] &= 0xffffffffUL; /* for WORDSIZE > 32 machines */
-        i++;
-        if (i>=N) { mt[0] = mt[N-1]; i=1; }
-    }
-
-    mt[0] = 0x80000000UL; /* MSB is 1; assuring non-zero initial array */
-}
-
-/* generates a random number on [0,0xffffffff]-interval */
-unsigned long genrand_int32(void)
-{
-    unsigned long y;
-    static const 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;
-}
-
-/* generates a random number on [0,0x7fffffff]-interval */
-long genrand_int31(void)
-{
-    return (long)(genrand_int32()>>1);
-}
-
-/* generates a random number on [0,1]-real-interval */
-double genrand_real1(void)
-{
-    return genrand_int32()*(1.0/4294967295.0);
-    /* divided by 2^32-1 */
-}
-
-/* generates a random number on [0,1)-real-interval */
-double genrand_real2(void)
-{
-    return genrand_int32()*(1.0/4294967296.0);
-    /* divided by 2^32 */
-}
-
-/* generates a random number on (0,1)-real-interval */
-double genrand_real3(void)
-{
-    return (((double)genrand_int32()) + 0.5)*(1.0/4294967296.0);
-    /* divided by 2^32 */
-}
-
-/* generates a random number on [0,1) with 53-bit resolution*/
-double genrand_res53(void)
-{
-    unsigned long a=genrand_int32()>>5, b=genrand_int32()>>6;
-    return(a*67108864.0+b)*(1.0/9007199254740992.0);
-}
-/* These real versions are due to Isaku Wada, 2002/01/09 added */
-#endif /* dead_code */
diff --git a/mrbgems/mruby-random/src/mt19937ar.h b/mrbgems/mruby-random/src/mt19937ar.h
deleted file mode 100644
index 7d382320d..000000000
--- a/mrbgems/mruby-random/src/mt19937ar.h
+++ /dev/null
@@ -1,80 +0,0 @@
-/*
-** mt19937ar.h - MT Random functions
-**
-** Copyright (C) 1997 - 2016, Makoto Matsumoto and Takuji Nishimura,
-** 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 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 THE AUTHORS 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.
-**
-** [ MIT license: http://www.opensource.org/licenses/mit-license.php ]
-**
-** 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)
-**
-** This version is modified by mruby developers. If you see any problem,
-** contact us first at https://github.com/mruby/mruby/issues
-*/
-
-#define N 624
-
-typedef struct {
-  unsigned long mt[N];
-  int mti;
-  union {
-    unsigned long int_;
-    double double_;
-  } gen;
-
-  mrb_int seed;
-  mrb_bool has_seed : 1;
-} mt_state;
-
-void mrb_random_init_genrand(mt_state *, unsigned long);
-unsigned long mrb_random_genrand_int32(mt_state *);
-double mrb_random_genrand_real1(mt_state *t);
-
-/* initializes mt[N] with a seed */
-void init_genrand(unsigned long s);
-
-/* 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 init_by_array(unsigned long init_key[], int key_length);
-
-/* generates a random number on [0,0xffffffff]-interval */
-unsigned long genrand_int32(void);
-
-/* generates a random number on [0,0x7fffffff]-interval */
-long genrand_int31(void);
-
-/* These real versions are due to Isaku Wada, 2002/01/09 added */
-/* generates a random number on [0,1]-real-interval */
-double genrand_real1(void);
-
-/* generates a random number on [0,1)-real-interval */
-double genrand_real2(void);
-
-/* generates a random number on (0,1)-real-interval */
-double genrand_real3(void);
-
-/* generates a random number on [0,1) with 53-bit resolution*/
-double genrand_res53(void);
diff --git a/mrbgems/mruby-random/src/random.c b/mrbgems/mruby-random/src/random.c
index 99f2b02e4..bca565b17 100644
--- a/mrbgems/mruby-random/src/random.c
+++ b/mrbgems/mruby-random/src/random.c
@@ -4,71 +4,86 @@
 ** See Copyright Notice in mruby.h
 */
 
-#ifdef MRB_WITHOUT_FLOAT
-# error Conflict 'MRB_WITHOUT_FLOAT' configuration in your 'build_config.rb'
-#endif
-
 #include <mruby.h>
 #include <mruby/variable.h>
 #include <mruby/class.h>
 #include <mruby/data.h>
 #include <mruby/array.h>
-#include "mt19937ar.h"
 
 #include <time.h>
 
-static char const MT_STATE_KEY[] = "$mrb_i_mt_state";
+static char const RAND_STATE_KEY[] = "$mrb_i_rand_state";
 
-static const struct mrb_data_type mt_state_type = {
-  MT_STATE_KEY, mrb_free,
+static const struct mrb_data_type rand_state_type = {
+  RAND_STATE_KEY, mrb_free,
 };
 
-static mrb_value mrb_random_rand(mrb_state *mrb, mrb_value self);
-static mrb_value mrb_random_srand(mrb_state *mrb, mrb_value self);
+typedef struct rand_state {
+  uint32_t seed[4];
+} rand_state;
 
 static void
-mt_srand(mt_state *t, unsigned long seed)
+rand_init(rand_state *t)
 {
-  mrb_random_init_genrand(t, seed);
+  t->seed[0] = 123456789;
+  t->seed[1] = 362436069;
+  t->seed[2] = 521288629;
+  t->seed[3] = 88675123;
 }
 
-static unsigned long
-mt_rand(mt_state *t)
+static uint32_t
+rand_seed(rand_state *t, uint32_t seed)
 {
-  return mrb_random_genrand_int32(t);
+  uint32_t old_seed = t->seed[3];
+  rand_init(t);
+  t->seed[3] = seed;
+  return old_seed;
 }
 
-static double
-mt_rand_real(mt_state *t)
+static uint32_t
+rand_uint32(rand_state *state)
 {
-  return mrb_random_genrand_real1(t);
+  uint32_t *seed = state->seed;
+  uint32_t x = seed[0];
+  uint32_t y = seed[1];
+  uint32_t z = seed[2];
+  uint32_t w = seed[3]; 
+  uint32_t t;
+
+  t = x ^ (x << 11);
+  x = y; y = z; z = w;
+  w = (w ^ (w >> 19)) ^ (t ^ (t >> 8));
+  seed[0] = x;
+  seed[1] = y;
+  seed[2] = z;
+  seed[3] = w;
+
+  return w;
 }
 
-static mrb_value
-mrb_random_mt_srand(mrb_state *mrb, mt_state *t, mrb_value seed)
+#ifndef MRB_WITHOUT_FLOAT
+static double
+rand_real(rand_state *t)
 {
-  if (mrb_nil_p(seed)) {
-    seed = mrb_fixnum_value((mrb_int)(time(NULL) + mt_rand(t)));
-    if (mrb_fixnum(seed) < 0) {
-      seed = mrb_fixnum_value(0 - mrb_fixnum(seed));
-    }
-  }
-
-  mt_srand(t, (unsigned) mrb_fixnum(seed));
-
-  return seed;
+  uint32_t x = rand_uint32(t);
+  return x*(1.0/4294967295.0);
 }
+#endif
 
 static mrb_value
-mrb_random_mt_rand(mrb_state *mrb, mt_state *t, mrb_value max)
+random_rand(mrb_state *mrb, rand_state *t, mrb_value max)
 {
   mrb_value value;
 
   if (mrb_fixnum(max) == 0) {
-    value = mrb_float_value(mrb, mt_rand_real(t));
+#ifndef MRB_WITHOUT_FLOAT
+    value = mrb_float_value(mrb, rand_real(t));
+#else
+    mrb_raise(mrb, E_ARGUMENT_ERROR, "Float not supported");
+#endif
   }
   else {
-    value = mrb_fixnum_value(mt_rand(t) % mrb_fixnum(max));
+    value = mrb_fixnum_value(rand_uint32(t) % mrb_fixnum(max));
   }
 
   return value;
@@ -95,105 +110,70 @@ get_opt(mrb_state* mrb)
 }
 
 static mrb_value
-get_random(mrb_state *mrb) {
+random_default(mrb_state *mrb) {
   return mrb_const_get(mrb,
              mrb_obj_value(mrb_class_get(mrb, "Random")),
              mrb_intern_lit(mrb, "DEFAULT"));
 }
 
-static mt_state *
-get_random_state(mrb_state *mrb)
-{
-  mrb_value random_val = get_random(mrb);
-  return DATA_GET_PTR(mrb, random_val, &mt_state_type, mt_state);
-}
-
-static mrb_value
-mrb_random_g_rand(mrb_state *mrb, mrb_value self)
-{
-  mrb_value random = get_random(mrb);
-  return mrb_random_rand(mrb, random);
-}
-
-static mrb_value
-mrb_random_g_srand(mrb_state *mrb, mrb_value self)
+static rand_state *
+random_state(mrb_state *mrb)
 {
-  mrb_value random = get_random(mrb);
-  return mrb_random_srand(mrb, random);
+  mrb_value random_val = random_default(mrb);
+  return DATA_GET_PTR(mrb, random_val, &rand_state_type, rand_state);
 }
 
 static mrb_value
-mrb_random_init(mrb_state *mrb, mrb_value self)
+random_m_init(mrb_state *mrb, mrb_value self)
 {
   mrb_value seed;
-  mt_state *t;
+  rand_state *t;
 
   seed = get_opt(mrb);
-
   /* avoid memory leaks */
-  t = (mt_state*)DATA_PTR(self);
-  if (t) {
-    mrb_free(mrb, t);
+  t = (rand_state*)DATA_PTR(self);
+  if (t == NULL) {
+    t = (rand_state *)mrb_malloc(mrb, sizeof(rand_state));
+    mrb_data_init(self, t, &rand_state_type);
   }
-  mrb_data_init(self, NULL, &mt_state_type);
-
-  t = (mt_state *)mrb_malloc(mrb, sizeof(mt_state));
-  t->mti = N + 1;
-
-  seed = mrb_random_mt_srand(mrb, t, seed);
   if (mrb_nil_p(seed)) {
-    t->has_seed = FALSE;
+    rand_init(t);
   }
   else {
-    mrb_assert(mrb_fixnum_p(seed));
-    t->has_seed = TRUE;
-    t->seed = mrb_fixnum(seed);
+    rand_seed(t, (uint32_t)mrb_fixnum(seed));
   }
 
-  mrb_data_init(self, t, &mt_state_type);
-
   return self;
 }
 
-static void
-mrb_random_rand_seed(mrb_state *mrb, mt_state *t)
-{
-  if (!t->has_seed) {
-    mrb_random_mt_srand(mrb, t, mrb_nil_value());
-  }
-}
-
 static mrb_value
-mrb_random_rand(mrb_state *mrb, mrb_value self)
+random_m_rand(mrb_state *mrb, mrb_value self)
 {
   mrb_value max;
-  mt_state *t = DATA_GET_PTR(mrb, self, &mt_state_type, mt_state);
+  rand_state *t = DATA_GET_PTR(mrb, self, &rand_state_type, rand_state);
 
   max = get_opt(mrb);
-  mrb_random_rand_seed(mrb, t);
-  return mrb_random_mt_rand(mrb, t, max);
+  return random_rand(mrb, t, max);
 }
 
 static mrb_value
-mrb_random_srand(mrb_state *mrb, mrb_value self)
+random_m_srand(mrb_state *mrb, mrb_value self)
 {
-  mrb_value seed;
-  mrb_value old_seed;
-  mt_state *t = DATA_GET_PTR(mrb, self, &mt_state_type, mt_state);
-
-  seed = get_opt(mrb);
-  seed = mrb_random_mt_srand(mrb, t, seed);
-  old_seed = t->has_seed? mrb_fixnum_value(t->seed) : mrb_nil_value();
-  if (mrb_nil_p(seed)) {
-    t->has_seed = FALSE;
+  uint32_t seed;
+  uint32_t old_seed;
+  mrb_value sv;
+  rand_state *t = DATA_GET_PTR(mrb, self, &rand_state_type, rand_state);
+
+  sv = get_opt(mrb);
+  if (mrb_nil_p(sv)) {
+    seed = (uint32_t)time(NULL) + rand_uint32(t);
   }
   else {
-    mrb_assert(mrb_fixnum_p(seed));
-    t->has_seed = TRUE;
-    t->seed = mrb_fixnum(seed);
+    seed = (uint32_t)mrb_fixnum(sv);
   }
+  old_seed = rand_seed(t, seed);
 
-  return old_seed;
+  return mrb_fixnum_value((mrb_int)old_seed);
 }
 
 /*
@@ -207,25 +187,23 @@ static mrb_value
 mrb_ary_shuffle_bang(mrb_state *mrb, mrb_value ary)
 {
   mrb_int i;
-  mt_state *random = NULL;
+  mrb_value max;
+  rand_state *random = NULL;
 
   if (RARRAY_LEN(ary) > 1) {
-    mrb_get_args(mrb, "|d", &random, &mt_state_type);
+    mrb_get_args(mrb, "|d", &random, &rand_state_type);
 
     if (random == NULL) {
-      random = get_random_state(mrb);
+      random = random_state(mrb);
     }
-    mrb_random_rand_seed(mrb, random);
-
     mrb_ary_modify(mrb, mrb_ary_ptr(ary));
-
+    max = mrb_fixnum_value(RARRAY_LEN(ary));
     for (i = RARRAY_LEN(ary) - 1; i > 0; i--)  {
       mrb_int j;
       mrb_value *ptr = RARRAY_PTR(ary);
       mrb_value tmp;
 
-
-      j = mrb_fixnum(mrb_random_mt_rand(mrb, random, mrb_fixnum_value(RARRAY_LEN(ary))));
+      j = mrb_fixnum(random_rand(mrb, random, max));
 
       tmp = ptr[i];
       ptr[i] = ptr[j];
@@ -272,15 +250,13 @@ mrb_ary_sample(mrb_state *mrb, mrb_value ary)
 {
   mrb_int n = 0;
   mrb_bool given;
-  mt_state *random = NULL;
+  rand_state *random = NULL;
   mrb_int len;
 
-  mrb_get_args(mrb, "|i?d", &n, &given, &random, &mt_state_type);
+  mrb_get_args(mrb, "|i?d", &n, &given, &random, &rand_state_type);
   if (random == NULL) {
-    random = get_random_state(mrb);
+    random = random_state(mrb);
   }
-  mrb_random_rand_seed(mrb, random);
-  mt_rand(random);
   len = RARRAY_LEN(ary);
   if (!given) {                 /* pick one element */
     switch (len) {
@@ -289,7 +265,7 @@ mrb_ary_sample(mrb_state *mrb, mrb_value ary)
     case 1:
       return RARRAY_PTR(ary)[0];
     default:
-      return RARRAY_PTR(ary)[mt_rand(random) % len];
+      return RARRAY_PTR(ary)[rand_uint32(random) % len];
     }
   }
   else {
@@ -304,7 +280,7 @@ mrb_ary_sample(mrb_state *mrb, mrb_value ary)
 
       for (;;) {
       retry:
-        r = mt_rand(random) % len;
+        r = (mrb_int)rand_uint32(random) % len;
 
         for (j=0; j<i; j++) {
           if (mrb_fixnum(RARRAY_PTR(result)[j]) == r) {
@@ -322,23 +298,37 @@ mrb_ary_sample(mrb_state *mrb, mrb_value ary)
   }
 }
 
+static mrb_value
+random_f_rand(mrb_state *mrb, mrb_value self)
+{
+  rand_state *t = random_state(mrb);
+  return random_rand(mrb, t, get_opt(mrb));
+}
+
+static mrb_value
+random_f_srand(mrb_state *mrb, mrb_value self)
+{
+  mrb_value random = random_default(mrb);
+  return random_m_srand(mrb, random);
+}
+
 
 void mrb_mruby_random_gem_init(mrb_state *mrb)
 {
   struct RClass *random;
   struct RClass *array = mrb->array_class;
 
-  mrb_define_method(mrb, mrb->kernel_module, "rand", mrb_random_g_rand, MRB_ARGS_OPT(1));
-  mrb_define_method(mrb, mrb->kernel_module, "srand", mrb_random_g_srand, MRB_ARGS_OPT(1));
+  mrb_define_method(mrb, mrb->kernel_module, "rand", random_f_rand, MRB_ARGS_OPT(1));
+  mrb_define_method(mrb, mrb->kernel_module, "srand", random_f_srand, MRB_ARGS_OPT(1));
 
   random = mrb_define_class(mrb, "Random", mrb->object_class);
   MRB_SET_INSTANCE_TT(random, MRB_TT_DATA);
-  mrb_define_class_method(mrb, random, "rand", mrb_random_g_rand, MRB_ARGS_OPT(1));
-  mrb_define_class_method(mrb, random, "srand", mrb_random_g_srand, MRB_ARGS_OPT(1));
+  mrb_define_class_method(mrb, random, "rand", random_f_rand, MRB_ARGS_OPT(1));
+  mrb_define_class_method(mrb, random, "srand", random_f_srand, MRB_ARGS_OPT(1));
 
-  mrb_define_method(mrb, random, "initialize", mrb_random_init, MRB_ARGS_OPT(1));
-  mrb_define_method(mrb, random, "rand", mrb_random_rand, MRB_ARGS_OPT(1));
-  mrb_define_method(mrb, random, "srand", mrb_random_srand, MRB_ARGS_OPT(1));
+  mrb_define_method(mrb, random, "initialize", random_m_init, MRB_ARGS_OPT(1));
+  mrb_define_method(mrb, random, "rand", random_m_rand, MRB_ARGS_OPT(1));
+  mrb_define_method(mrb, random, "srand", random_m_srand, MRB_ARGS_OPT(1));
 
   mrb_define_method(mrb, array, "shuffle", mrb_ary_shuffle, MRB_ARGS_OPT(1));
   mrb_define_method(mrb, array, "shuffle!", mrb_ary_shuffle_bang, MRB_ARGS_OPT(1));