Switch random generator from Mersenne Twister to Xorshit128.

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

1 files changed, 108 insertions, 118 deletions

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));