/* generic file for evaluation of hypergeometric series using binary splitting

Copyright (C) 1999-2001 Free Software Foundation.

This file is part of the MPFR Library.

The MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.

The MPdFR Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the MPFR Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */

#ifndef GENERIC
 # error You should specify a name 
#endif

#ifdef B
#  ifndef A
 #   error B cannot be used without A
#  endif
#endif

/* Compute the first 2^m terms from the hypergeometric series
   with x = p / 2^r */
static int
GENERIC (mpfr_ptr y, mpz_srcptr p, int r, int m)
{
  int n,i,k,j,l;
  int is_p_one = 0;
  mpz_t* P,*S;
#ifdef A
  mpz_t *T;
#endif
  mpz_t* ptoj;
#ifdef R_IS_RATIONAL
  mpz_t* qtoj;
  mpfr_t tmp;
#endif
  int diff, expo;
  int precy = MPFR_PREC(y);
  TMP_DECL(marker);

  TMP_MARK(marker);
  MPFR_CLEAR_FLAGS(y); 
  n = 1 << m;
  P = (mpz_t*) TMP_ALLOC ((m+1) * sizeof(mpz_t));
  S = (mpz_t*) TMP_ALLOC ((m+1) * sizeof(mpz_t));
  ptoj = (mpz_t*) TMP_ALLOC ((m+1) * sizeof(mpz_t)); /* ptoj[i] = mantissa^(2^i) */
#ifdef A
  T = (mpz_t*) TMP_ALLOC ((m+1) * sizeof(mpz_t));
#endif
#ifdef R_IS_RATIONAL
  qtoj = (mpz_t*) TMP_ALLOC ((m+1) * sizeof(mpz_t));
#endif
  for (i=0;i<=m;i++)
    {
      mpz_init (P[i]);
      mpz_init (S[i]);
      mpz_init (ptoj[i]);
#ifdef R_IS_RATIONAL
      mpz_init (qtoj[i]);
#endif
#ifdef A
      mpz_init (T[i]);
#endif
    }
  mpz_set (ptoj[0], p);
#ifdef C
#  if C2 != 1
  mpz_mul_ui(ptoj[0], ptoj[0], C2);
#  endif
#endif
  is_p_one = !mpz_cmp_si(ptoj[0], 1);
#ifdef A
#  ifdef B
  mpz_set_ui(T[0], A1 * B1);
#  else
  mpz_set_ui(T[0], A1);
#  endif
#endif
  if (!is_p_one) 
  for (i=1;i<m;i++) mpz_mul(ptoj[i], ptoj[i-1], ptoj[i-1]);
#ifdef R_IS_RATIONAL
  mpz_set_si(qtoj[0], r);
  for (i=1;i<=m;i++) 
    {
      mpz_mul(qtoj[i], qtoj[i-1], qtoj[i-1]);
    }
#endif

  mpz_set_ui(P[0], 1);
  mpz_set_ui(S[0], 1);
  k = 0;
  for (i=1;(i < n) ;i++) {
    k++;
    
#ifdef A
#  ifdef B 
    mpz_set_ui(T[k], (A1 + A2*i)*(B1+B2*i));
#  else
    mpz_set_ui(T[k], A1 + A2*i);
#  endif
#endif
    
#ifdef C
#  ifdef NO_FACTORIAL
    mpz_set_ui(P[k], (C1 + C2 * (i-1)));
    mpz_set_ui(S[k], 1);
#  else
    mpz_set_ui(P[k], (i+1) * (C1 + C2 * (i-1)));
    mpz_set_ui(S[k], i+1);
#  endif
#else
#  ifdef NO_FACTORIAL
    mpz_set_ui(P[k], 1);
#  else
    mpz_set_ui(P[k], i+1);
#  endif
    mpz_set(S[k], P[k]);
#endif
    j=i+1; l=0; while ((j & 1) == 0) {      
      if (!is_p_one) 
	mpz_mul(S[k], S[k], ptoj[l]);
#ifdef A
#  ifdef B
#    if (A2*B2) != 1
      mpz_mul_ui(P[k], P[k], A2*B2);
#    endif
#  else
#    if A2 != 1 
      mpz_mul_ui(P[k], P[k], A2);
#  endif
#endif
      mpz_mul(S[k], S[k], T[k-1]);
#endif
      mpz_mul(S[k-1], S[k-1], P[k]);
#ifdef R_IS_RATIONAL
      mpz_mul(S[k-1], S[k-1], qtoj[l]);
#else
      mpz_mul_2exp(S[k-1], S[k-1], r*(1<<l));
#endif
      mpz_add(S[k-1], S[k-1], S[k]);
      mpz_mul(P[k-1], P[k-1], P[k]);
#ifdef A
      mpz_mul(T[k-1], T[k-1], T[k]);
#endif
      l++; j>>=1; k--;
    }
  }

  diff = mpz_sizeinbase(S[0],2) - 2*precy;
  expo = diff;
  if (diff >=0)
    {
      mpz_div_2exp(S[0],S[0],diff);
    } else 
      {
	mpz_mul_2exp(S[0],S[0],-diff);
      }
  diff = mpz_sizeinbase(P[0],2) - precy;
  expo -= diff;
  if (diff >=0)
    {
      mpz_div_2exp(P[0],P[0],diff);
    } else
      {
	mpz_mul_2exp(P[0],P[0],-diff);
	}

  mpz_tdiv_q(S[0], S[0], P[0]);
  mpfr_set_z(y, S[0], GMP_RNDD);
  MPFR_EXP(y) += expo; 

#ifdef R_IS_RATIONAL
  /* exact division */
  mpz_div_ui (qtoj[m], qtoj[m], r);
  mpfr_init2 (tmp, MPFR_PREC(y));
  mpfr_set_z (tmp, qtoj[m] , GMP_RNDD);
  mpfr_div (y, y, tmp, GMP_RNDD);
  mpfr_clear (tmp);
#else
  mpfr_div_2exp(y, y, r*(i-1), GMP_RNDN);
#endif
  for (i=0;i<=m;i++)
    {
      mpz_clear (P[i]);
      mpz_clear (S[i]);
      mpz_clear (ptoj[i]); 
#ifdef R_IS_RATIONAL
      mpz_clear (qtoj[i]);
#endif
#ifdef A
      mpz_clear (T[i]);
#endif
    }
  TMP_FREE(marker);
  return 0;
}