Rietveld Code Review Tool
Help | Bug tracker | Discussion group | Source code | Sign in
(13)

Unified Diff: Modules/_randommodule.c

Issue 13704: Random number generator in Python core
Patch Set: Created 8 years ago
Use n/p to move between diff chunks; N/P to move between comments. Please Sign in to add in-line comments.
Jump to:
View side-by-side diff with in-line comments
Download patch
--- a/Modules/_randommodule.c Fri Dec 30 21:26:08 2011 +0100
+++ b/Modules/_randommodule.c Tue Jan 03 21:48:43 2012 +0100
@@ -1,85 +1,13 @@
/* Random objects */
-
-/* ------------------------------------------------------------------
- The code in this module was based on a download from:
- http://www.math.keio.ac.jp/~matumoto/MT2002/emt19937ar.html
-
- It was modified in 2002 by Raymond Hettinger as follows:
-
- * the principal computational lines untouched.
-
- * renamed genrand_res53() to random_random() and wrapped
- in python calling/return code.
-
- * genrand_int32() and the helper functions, init_genrand()
- and init_by_array(), were declared static, wrapped in
- Python calling/return code. also, their global data
- references were replaced with structure references.
-
- * unused functions from the original were deleted.
- new, original C python code was added to implement the
- Random() interface.
-
- The following are the verbatim comments from the original code:
-
- 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.keio.ac.jp/matumoto/emt.html
- email: matumoto@math.keio.ac.jp
-*/
-
-/* ---------------------------------------------------------------*/
-
#include "Python.h"
+#include "pyrandom.h"
#include <time.h> /* for seeding to current time */
-/* Period parameters -- These are all magic. Don't change. */
-#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 */
+#define N _Py_MT_N
typedef struct {
PyObject_HEAD
- unsigned long state[N];
- int index;
+ _Py_MT_RandomState rs;
} RandomObject;
static PyTypeObject Random_Type;
@@ -87,123 +15,19 @@
#define RandomObject_Check(v) (Py_TYPE(v) == &Random_Type)
-/* Random methods */
-
-
-/* generates a random number on [0,0xffffffff]-interval */
-static unsigned long
-genrand_int32(RandomObject *self)
-{
- unsigned long y;
- static unsigned long mag01[2]={0x0UL, MATRIX_A};
- /* mag01[x] = x * MATRIX_A for x=0,1 */
- unsigned long *mt;
-
- mt = self->state;
- if (self->index >= 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];
-
- self->index = 0;
- }
-
- y = mt[self->index++];
- y ^= (y >> 11);
- y ^= (y << 7) & 0x9d2c5680UL;
- y ^= (y << 15) & 0xefc60000UL;
- y ^= (y >> 18);
- return y;
-}
-
-/* random_random is the function named genrand_res53 in the original code;
- * generates a random number on [0,1) with 53-bit resolution; note that
- * 9007199254740992 == 2**53; I assume they're spelling "/2**53" as
- * multiply-by-reciprocal in the (likely vain) hope that the compiler will
- * optimize the division away at compile-time. 67108864 is 2**26. In
- * effect, a contains 27 random bits shifted left 26, and b fills in the
- * lower 26 bits of the 53-bit numerator.
- * The orginal code credited Isaku Wada for this algorithm, 2002/01/09.
- */
-static PyObject *
-random_random(RandomObject *self)
-{
- unsigned long a=genrand_int32(self)>>5, b=genrand_int32(self)>>6;
- return PyFloat_FromDouble((a*67108864.0+b)*(1.0/9007199254740992.0));
-}
-
-/* initializes mt[N] with a seed */
-static void
-init_genrand(RandomObject *self, unsigned long s)
-{
- int mti;
- unsigned long *mt;
-
- mt = self->state;
- 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 */
- }
- self->index = mti;
- return;
-}
-
-/* initialize by an array with array-length */
-/* init_key is the array for initializing keys */
-/* key_length is its length */
-static PyObject *
-init_by_array(RandomObject *self, unsigned long init_key[], unsigned long key_length)
-{
- unsigned int i, j, k; /* was signed in the original code. RDH 12/16/2002 */
- unsigned long *mt;
-
- mt = self->state;
- init_genrand(self, 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 */
- Py_INCREF(Py_None);
- return Py_None;
-}
-
/*
* The rest is Python-specific code, neither part of, nor derived from, the
* Twister download.
*/
static PyObject *
+random_random(RandomObject *self)
+{
+ return PyFloat_FromDouble(_Py_MT_GenRand_Res53(&self->rs));
+}
+
+
+static PyObject *
random_seed(RandomObject *self, PyObject *args)
{
PyObject *result = NULL; /* guilty until proved innocent */
@@ -224,7 +48,7 @@
time_t now;
time(&now);
- init_genrand(self, (unsigned long)now);
+ _Py_MT_GenRand_Init(&self->rs, (unsigned long)now);
Py_INCREF(Py_None);
return Py_None;
}
@@ -299,7 +123,9 @@
if (keyused == 0)
key[keyused++] = 0UL;
- result = init_by_array(self, key, keyused);
+ _Py_MT_GenRand_InitArray(&self->rs, key, keyused);
+ Py_INCREF(Py_None);
+ result = Py_None;
Done:
Py_XDECREF(masklower);
Py_XDECREF(thirtytwo);
@@ -319,12 +145,12 @@
if (state == NULL)
return NULL;
for (i=0; i<N ; i++) {
- element = PyLong_FromUnsignedLong(self->state[i]);
+ element = PyLong_FromUnsignedLong(self->rs.state[i]);
if (element == NULL)
goto Fail;
PyTuple_SET_ITEM(state, i, element);
}
- element = PyLong_FromLong((long)(self->index));
+ element = PyLong_FromLong((long)(self->rs.index));
if (element == NULL)
goto Fail;
PyTuple_SET_ITEM(state, i, element);
@@ -357,13 +183,13 @@
element = PyLong_AsUnsignedLong(PyTuple_GET_ITEM(state, i));
if (element == (unsigned long)-1 && PyErr_Occurred())
return NULL;
- self->state[i] = element & 0xffffffffUL; /* Make sure we get sane state */
+ self->rs.state[i] = element & 0xffffffffUL; /* Make sure we get sane state */
}
index = PyLong_AsLong(PyTuple_GET_ITEM(state, i));
if (index == -1 && PyErr_Occurred())
return NULL;
- self->index = (int)index;
+ self->rs.index = (int)index;
Py_INCREF(Py_None);
return Py_None;
@@ -395,7 +221,7 @@
/* Fill-out whole words, byte-by-byte to avoid endianness issues */
for (i=0 ; i<bytes ; i+=4, k-=32) {
- r = genrand_int32(self);
+ r = _Py_MT_GenRand_Int32(&self->rs);
if (k < 32)
r >>= (32 - k);
bytearray[i+0] = (unsigned char)r;

RSS Feeds Recent Issues | This issue
This is Rietveld 894c83f36cb7+