| /* mpfr_cache -- cache interface for multi-precision const in MPFR. |
| |
| Copyright 2004, 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc. |
| Contributed by the Arenaire and Cacao projects, INRIA. |
| |
| This file is part of the GNU MPFR Library. |
| |
| The GNU 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 GNU MPFR 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 GNU MPFR Library; see the file COPYING.LIB. If not, write to |
| the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, |
| MA 02110-1301, USA. */ |
| |
| #include "mpfr-impl.h" |
| |
| void |
| mpfr_init_cache (mpfr_cache_t cache, int (*func)(mpfr_ptr, mp_rnd_t)) |
| { |
| MPFR_PREC (cache->x) = 0; /* Invalid prec to detect that the cache is not |
| valid. Maybe add a flag? */ |
| cache->func = func; |
| } |
| |
| void |
| mpfr_clear_cache (mpfr_cache_t cache) |
| { |
| if (MPFR_PREC (cache->x) != 0) |
| mpfr_clear (cache->x); |
| MPFR_PREC (cache->x) = 0; |
| } |
| |
| int |
| mpfr_cache (mpfr_ptr dest, mpfr_cache_t cache, mp_rnd_t rnd) |
| { |
| mp_prec_t prec = MPFR_PREC (dest); |
| mp_prec_t pold = MPFR_PREC (cache->x); |
| int inexact, sign; |
| MPFR_SAVE_EXPO_DECL (expo); |
| |
| MPFR_SAVE_EXPO_MARK (expo); |
| |
| if (MPFR_UNLIKELY (prec > pold)) |
| { |
| /* No previous result in the cache or the precision of the |
| previous result is not sufficient. */ |
| |
| if (MPFR_UNLIKELY (pold == 0)) /* No previous result. */ |
| mpfr_init2 (cache->x, prec); |
| |
| /* Update the cache. */ |
| pold = prec; |
| mpfr_prec_round (cache->x, pold, GMP_RNDN); |
| cache->inexact = (*cache->func) (cache->x, GMP_RNDN); |
| } |
| |
| /* First, check if the cache has the exact value (unlikely). |
| Else the exact value is between (assuming x=cache->x > 0): |
| x and x+ulp(x) if cache->inexact < 0, |
| x-ulp(x) and x if cache->inexact > 0, |
| and abs(x-exact) <= ulp(x)/2. */ |
| MPFR_ASSERTN (MPFR_IS_POS (cache->x)); /* TODO... */ |
| sign = MPFR_SIGN (cache->x); |
| MPFR_SET_EXP (dest, MPFR_GET_EXP (cache->x)); |
| MPFR_SET_SIGN (dest, sign); |
| MPFR_RNDRAW_GEN (inexact, dest, |
| MPFR_MANT (cache->x), MPFR_PREC (cache->x), rnd, sign, |
| if (MPFR_UNLIKELY (cache->inexact == 0)) |
| { |
| if ((_sp[0] & _ulp) == 0) |
| { |
| inexact = -sign; |
| goto trunc_doit; |
| } |
| else |
| goto addoneulp; |
| } |
| else if (cache->inexact < 0) |
| goto addoneulp; |
| else |
| { |
| inexact = -sign; |
| goto trunc_doit; |
| }, |
| if (MPFR_UNLIKELY (++MPFR_EXP (dest) > __gmpfr_emax)) |
| mpfr_overflow (dest, rnd, sign); |
| ); |
| if (MPFR_LIKELY (cache->inexact != 0)) |
| { |
| switch (rnd) |
| { |
| case GMP_RNDZ: |
| case GMP_RNDD: |
| if (MPFR_UNLIKELY (inexact == 0)) |
| { |
| inexact = cache->inexact; |
| if (inexact > 0) |
| mpfr_nextbelow (dest); |
| } |
| break; |
| case GMP_RNDU: |
| if (MPFR_UNLIKELY (inexact == 0)) |
| { |
| inexact = cache->inexact; |
| if (inexact < 0) |
| mpfr_nextabove (dest); |
| } |
| break; |
| default: /* GMP_RNDN */ |
| if (MPFR_UNLIKELY(inexact == 0)) |
| inexact = cache->inexact; |
| break; |
| } |
| } |
| |
| MPFR_SAVE_EXPO_FREE (expo); |
| return mpfr_check_range (dest, inexact, rnd); |
| } |