/* seive.c */

/*
  Copyright (C) 2001-2009 Makoto Matsumoto and Takuji Nishimura.
  Copyright (C) 2009 Mutsuo Saito
  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.

  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.
*/

#include <stdio.h>
#include <stdlib.h>
#include "dci.h"

#define WORDLEN 32
#define LSB 0x1
#define MAX_SEARCH 10000


_org_state global_mt19937;
/*******************************************************************/
static uint32_t nextA(_org_state *org, int w);
static uint32_t nextA_id(_org_state *org, int w, int id, int idw);
static void make_masks(int r, int w, mt_struct *mts);
static int get_irred_param(check32_t *ck, prescr_t *pre, _org_state *org,
			   mt_struct *mts,int id, int idw);
static mt_struct *alloc_mt_struct(int n);
static mt_struct *init_mt_search(check32_t *ck, prescr_t *pre, int w, int p);
static void end_mt_search(prescr_t *pre);
static void copy_params_of_mt_struct(mt_struct *src, mt_struct *dst);
static int proper_mersenne_exponent(int p);
/*******************************************************************/

/* When idw==0, id is not embedded into "a" */
#define FOUND 1
#define NOT_FOUND 0
static int get_irred_param(check32_t *ck, prescr_t *pre, _org_state *org,
			   mt_struct *mts, int id, int idw)
{
    int i;
    uint32_t a;

    for (i=0; i<MAX_SEARCH; i++) {
	if (idw == 0)
	    a = nextA(org, mts->ww);
	else
	    a = nextA_id(org, mts->ww, id, idw);
	if (NOT_REJECTED == _prescreening_dc(pre, a) ) {
	    if (IRRED
		== _CheckPeriod_dc(ck, org, a,mts->mm,mts->nn,mts->rr,mts->ww)) {
		mts->aaa = a;
		break;
	    }
	}
    }

    if (MAX_SEARCH == i) return NOT_FOUND;
    return FOUND;
}


static uint32_t nextA(_org_state *org, int w)
{
    uint32_t x, word_mask;

    word_mask = 0xFFFFFFFF;
    word_mask <<= WORDLEN - w;
    word_mask >>= WORDLEN - w;

    x = _genrand_dc(org);
    x &= word_mask;
    x |= (LSB << (w-1));

    return x;
}

static uint32_t nextA_id(_org_state *org, int w, int id, int idw)
{
    uint32_t x, word_mask;

    word_mask = 0xFFFFFFFF;
    word_mask <<= WORDLEN - w;
    word_mask >>= WORDLEN - w;
    word_mask >>= idw;
    word_mask <<= idw;

    x = _genrand_dc(org);
    x &= word_mask;
    x |= (LSB << (w-1));
    x |= (uint32_t)id; /* embedding id */

    return x;
}

static void make_masks(int r, int w, mt_struct *mts)
{
    int i;
    uint32_t ut, wm, um, lm;

    wm = 0xFFFFFFFF;
    wm >>= (WORDLEN - w);

    ut = 0;
    for (i=0; i<r; i++) {
	ut <<= 1;
	ut |= LSB;
    }

    lm = ut;
    um = (~ut) & wm;

    mts->wmask = wm;
    mts->umask = um;
    mts->lmask = lm;
}

static mt_struct *init_mt_search(check32_t *ck, prescr_t *pre, int w, int p)
{
    int n, m, r;
    mt_struct *mts;

    if (w > 32 || w < 31) {
	printf("Sorry, currently only w = 32 or 31 is allowed.\n");
	return NULL;
    }

    if (!proper_mersenne_exponent(p)) {
	if (p < 521) {
	    printf ("\"p\" is too small.\n");
	    return NULL;
	} else if (p > 44497) {
	    printf("\"p\" is too large.\n");
	    return NULL;
	} else {
	    printf("\"p\" is not a Mersenne exponent.\n");
	    return NULL;
	}
    }

    n = p/w + 1; /* since p is Mersenne Exponent, w never divids p */
    mts = alloc_mt_struct(n);
    if (NULL == mts) return NULL;

    m = n/2;
    if (m < 2) m = n-1;
    r = n * w - p;

    make_masks(r, w, mts);
    _InitPrescreening_dc(pre, m, n, r, w);
    _InitCheck32_dc(ck, r, w);

    mts->mm = m;
    mts->nn = n;
    mts->rr = r;
    mts->ww = w;

    return mts;
}

static void end_mt_search(prescr_t *pre)
{
    _EndPrescreening_dc(pre);
}

/*
   w -- word size
   p -- Mersenne Exponent
   seed -- seed for original mt19937 to generate parameter.
*/
mt_struct *get_mt_parameter_st(int w, int p, uint32_t seed)
{
    mt_struct *mts;
    prescr_t pre;
    _org_state org;
    check32_t ck;

    _sgenrand_dc(&org, seed);
    mts = init_mt_search(&ck, &pre, w, p);
    if (mts == NULL) return NULL;

    if ( NOT_FOUND == get_irred_param(&ck, &pre, &org, mts,0,0) ) {
	free_mt_struct(mts);
	return NULL;
    }
    _get_tempering_parameter_hard_dc(mts);
    end_mt_search(&pre);

    return mts;
}

/*
   w -- word size
   p -- Mersenne Exponent
*/
#if 0
mt_struct *get_mt_parameter_opt_temper(int w, int p, uint32_t seed)
{
    mt_struct *mts;
    prescr_t pre;
    _org_state org;
    check32_t ck;

    _sgenrand_dc(&org, seed);
    mts = init_mt_search(&ck, &pre, w, p);
    if (mts == NULL) return NULL;

    if ( NOT_FOUND == get_irred_param(&ck, &pre, &org, mts,0,0) ) {
	free_mt_struct(mts);
	return NULL;
    }
    _get_tempering_parameter_hard_dc(mts);
    end_mt_search(&pre);

    return mts;
}
#endif
/*
   w -- word size
   p -- Mersenne Exponent
*/
#define DEFAULT_ID_SIZE 16
/* id <= 0xffff */
mt_struct *get_mt_parameter_id_st(int w, int p, int id, uint32_t seed)
{
    mt_struct *mts;
    prescr_t pre;
    _org_state org;
    check32_t ck;

    _sgenrand_dc(&org, seed);
    if (id > 0xffff) {
	printf("\"id\" must be less than 65536\n");
	return NULL;
    }
    if (id < 0) {
	printf("\"id\" must be positive\n");
	return NULL;
    }

    mts = init_mt_search(&ck, &pre, w, p);
    if (mts == NULL) return NULL;

    if ( NOT_FOUND == get_irred_param(&ck, &pre, &org,
				      mts, id, DEFAULT_ID_SIZE) ) {
	free_mt_struct(mts);
	return NULL;
    }
    _get_tempering_parameter_hard_dc(mts);
    end_mt_search(&pre);

    return mts;
}

mt_struct **get_mt_parameters_st (int w, int p, int start_id,
				  int max_id, uint32_t seed,
				  int *count)
{
    mt_struct **mtss, *template_mts;
    int i;
    prescr_t pre;
    _org_state org;
    check32_t ck;

    if (start_id > max_id || max_id > 0xffff || start_id < 0) {
	printf("\"id\" error\n");
	return NULL;
    }

    _sgenrand_dc(&org, seed);
    mtss = malloc(sizeof *mtss * (max_id-start_id+1));
    if (NULL == mtss) {
	return NULL;
    }

    template_mts = init_mt_search(&ck, &pre, w, p);
    if (template_mts == NULL) {
	free(mtss);
	return NULL;
    }
    
    *count = 0;
    
    for (i=0; i<=max_id-start_id; i++) {
	mtss[i] = alloc_mt_struct(template_mts->nn);
	if (NULL == mtss[i]) {
	    break;
	}

	copy_params_of_mt_struct(template_mts, mtss[i]);

	if (NOT_FOUND == get_irred_param(&ck, &pre, &org, mtss[i],
					  i+start_id,DEFAULT_ID_SIZE)) {
	    free_mt_struct(mtss[i]);
	    break;
	}
	_get_tempering_parameter_hard_dc(mtss[i]);
	++(*count);
    }
    
    free_mt_struct(template_mts);
    end_mt_search(&pre);
    
    if (*count > 0) {
	return mtss;
    } else {
	free(mtss);
	return NULL;
    }
}

/* n : sizeof state vector */
static mt_struct *alloc_mt_struct (int n)
{
    mt_struct *mts;

    mts = (mt_struct*)malloc(sizeof(mt_struct));
    if (NULL == mts) return NULL;
    mts->state = (uint32_t*)malloc(n*sizeof(uint32_t));
    if (NULL == mts->state) {
	free(mts);
	return NULL;
    }

    return mts;
}

void free_mt_struct (mt_struct *mts)
{
    free(mts->state);
    free(mts);
}

void free_mt_struct_array(mt_struct **mtss, int count)
{
    int i;

    if (mtss == NULL) {
	return;
    }
    for (i=0; i < count; i++) {
	free_mt_struct(mtss[i]);
    }
    free(mtss);
}

static void copy_params_of_mt_struct(mt_struct *src, mt_struct *dst)
{
    dst->nn = src->nn;
    dst->mm = src->mm;
    dst->rr = src->rr;
    dst->ww = src->ww;
    dst->wmask = src->wmask;
    dst->umask = src->umask;
    dst->lmask = src->lmask;
}

static int proper_mersenne_exponent(int p)
{
    switch(p) {
    case 521:
    case 607:
    case 1279:
    case 2203:
    case 2281:
    case 3217:
    case 4253:
    case 4423:
    case 9689:
    case 9941:
    case 11213:
    case 19937:
    case 21701:
    case 23209:
    case 44497:
	return 1;
    default:
	return 0;
    }
}
