gsl_microrng.h

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/*
Copyright 2010-2011, D. E. Shaw Research.
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

* Redistributions of source code must retain the above copyright
  notice, this list of conditions, and the following disclaimer.

* 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.

* Neither the name of D. E. Shaw Research nor the names of its
  contributors may 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,
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LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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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.
*/
#ifndef __r123_gslmicrorng_dot_h__
#define __r123_gslmicrorng_dot_h__


#include <gsl/gsl_rng.h>
#include <string.h>

#define GSL_MICRORNG(NAME, CBRNGNAME)                                   \
const gsl_rng_type *gsl_rng_##NAME;                                     \
                                                                        \
typedef struct{                                                         \
    CBRNGNAME##_ctr_t ctr;                                              \
    CBRNGNAME##_ctr_t r;                                                \
    CBRNGNAME##_key_t key;                                              \
    R123_ULONG_LONG n;                                                  \
    int elem;                                                           \
} NAME##_state;                                                         \
                                                                        \
static unsigned long int NAME##_get(void *vstate){                      \
    NAME##_state *st = (NAME##_state *)vstate;                          \
    const int N=sizeof(st->ctr.v)/sizeof(st->ctr.v[0]);                 \
    if( st->elem == 0 ){                                                \
        CBRNGNAME##_ctr_t c = st->ctr;                                  \
        c.v[N-1] |= st->n<<(R123_W(CBRNGNAME##_ctr_t)-32);              \
        st->n++;                                                        \
        st->r = CBRNGNAME(c, st->key);                                  \
        st->elem = N;                                                   \
    }                                                                   \
    return 0xffffffff & st->r.v[--st->elem];                            \
}                                                                       \
                                                                        \
static double                                                           \
NAME##_get_double (void * vstate)                                       \
{                                                                       \
    return NAME##_get (vstate)/4294967296.;                             \
}                                                                       \
                                                                        \
static void NAME##_set(void *vstate, unsigned long int s){              \
    NAME##_state *st = (NAME##_state *)vstate;                          \
    (void)s; /* ignored */                                              \
    st->elem = 0;                                                       \
    st->n = ~0; /* will abort if _reset is not called */                \
}                                                                       \
                                                                        \
static const gsl_rng_type NAME##_type = {                               \
    #NAME,                                                              \
    0xffffffffUL,                                                       \
    0,                                                                  \
    sizeof(NAME##_state),                                               \
    &NAME##_set,                                                        \
    &NAME##_get,                                                        \
    &NAME##_get_double                                                  \
};                                                                      \
                                                                        \
R123_STATIC_INLINE void NAME##_reset(const gsl_rng* gr, CBRNGNAME##_ctr_t c, CBRNGNAME##_key_t k) { \
    NAME##_state* state = (NAME##_state *)gr->state;                    \
    state->ctr = c;                                                     \
    state->key = k;                                                     \
    state->n = 0;                                                       \
    state->elem = 0;                                                    \
}                                                                       \
                                                                        \
const gsl_rng_type *gsl_rng_##NAME = &NAME##_type

#endif