chromium / native_client / nacl-gcc / f80d6b9ee7f94755c697ffb7194fb01dd0c537dd / . / mpfr-2.4.1 / sub.c

/* mpfr_sub -- subtract two floating-point numbers | |

Copyright 2001, 2002, 2003, 2004, 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" | |

int | |

mpfr_sub (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mp_rnd_t rnd_mode) | |

{ | |

MPFR_LOG_FUNC (("b[%#R]=%R c[%#R]=%R rnd=%d", b, b, c, c, rnd_mode), | |

("a[%#R]=%R", a, a)); | |

if (MPFR_ARE_SINGULAR (b,c)) | |

{ | |

if (MPFR_IS_NAN (b) || MPFR_IS_NAN (c)) | |

{ | |

MPFR_SET_NAN (a); | |

MPFR_RET_NAN; | |

} | |

else if (MPFR_IS_INF (b)) | |

{ | |

if (!MPFR_IS_INF (c) || MPFR_SIGN (b) != MPFR_SIGN(c)) | |

{ | |

MPFR_SET_INF (a); | |

MPFR_SET_SAME_SIGN (a, b); | |

MPFR_RET (0); /* exact */ | |

} | |

else | |

{ | |

MPFR_SET_NAN (a); /* Inf - Inf */ | |

MPFR_RET_NAN; | |

} | |

} | |

else if (MPFR_IS_INF (c)) | |

{ | |

MPFR_SET_INF (a); | |

MPFR_SET_OPPOSITE_SIGN (a, c); | |

MPFR_RET (0); /* exact */ | |

} | |

else if (MPFR_IS_ZERO (b)) | |

{ | |

if (MPFR_IS_ZERO (c)) | |

{ | |

int sign = rnd_mode != GMP_RNDD | |

? ((MPFR_IS_NEG(b) && MPFR_IS_POS(c)) ? -1 : 1) | |

: ((MPFR_IS_POS(b) && MPFR_IS_NEG(c)) ? 1 : -1); | |

MPFR_SET_SIGN (a, sign); | |

MPFR_SET_ZERO (a); | |

MPFR_RET(0); /* 0 - 0 is exact */ | |

} | |

else | |

return mpfr_neg (a, c, rnd_mode); | |

} | |

else | |

{ | |

MPFR_ASSERTD (MPFR_IS_ZERO (c)); | |

return mpfr_set (a, b, rnd_mode); | |

} | |

} | |

MPFR_CLEAR_FLAGS (a); | |

MPFR_ASSERTD (MPFR_IS_PURE_FP (b) && MPFR_IS_PURE_FP (c)); | |

if (MPFR_LIKELY (MPFR_SIGN (b) == MPFR_SIGN (c))) | |

{ /* signs are equal, it's a real subtraction */ | |

if (MPFR_LIKELY (MPFR_PREC (a) == MPFR_PREC (b) | |

&& MPFR_PREC (b) == MPFR_PREC (c))) | |

return mpfr_sub1sp (a, b, c, rnd_mode); | |

else | |

return mpfr_sub1 (a, b, c, rnd_mode); | |

} | |

else | |

{ /* signs differ, it's an addition */ | |

if (MPFR_GET_EXP (b) < MPFR_GET_EXP (c)) | |

{ /* exchange rounding modes towards +/- infinity */ | |

int inexact; | |

rnd_mode = MPFR_INVERT_RND (rnd_mode); | |

if (MPFR_LIKELY (MPFR_PREC (a) == MPFR_PREC (b) | |

&& MPFR_PREC (b) == MPFR_PREC (c))) | |

inexact = mpfr_add1sp (a, c, b, rnd_mode); | |

else | |

inexact = mpfr_add1 (a, c, b, rnd_mode); | |

MPFR_CHANGE_SIGN (a); | |

return -inexact; | |

} | |

else | |

{ | |

if (MPFR_LIKELY (MPFR_PREC (a) == MPFR_PREC (b) | |

&& MPFR_PREC (b) == MPFR_PREC (c))) | |

return mpfr_add1sp (a, b, c, rnd_mode); | |

else | |

return mpfr_add1 (a, b, c, rnd_mode); | |

} | |

} | |

} |