| /* mpfr_set_z -- set a floating-point number from a multiple-precision integer |
| |
| Copyright 1999, 2000, 2001, 2002, 2003, 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. */ |
| |
| #define MPFR_NEED_LONGLONG_H |
| #include "mpfr-impl.h" |
| |
| /* set f to the integer z */ |
| int |
| mpfr_set_z (mpfr_ptr f, mpz_srcptr z, mp_rnd_t rnd_mode) |
| { |
| mp_size_t fn, zn, dif; |
| int k, sign_z, inex; |
| mp_limb_t *fp, *zp; |
| mp_exp_t exp; |
| |
| sign_z = mpz_sgn (z); |
| if (MPFR_UNLIKELY (sign_z == 0)) |
| { |
| MPFR_SET_ZERO(f); |
| MPFR_SET_POS(f); |
| MPFR_RET(0); |
| } |
| MPFR_ASSERTD (sign_z == MPFR_SIGN_POS || sign_z == MPFR_SIGN_NEG); |
| |
| zn = ABS(SIZ(z)); |
| MPFR_ASSERTD (zn >= 1); |
| if (MPFR_UNLIKELY (zn > MPFR_EMAX_MAX / BITS_PER_MP_LIMB + 1)) |
| return mpfr_overflow (f, rnd_mode, sign_z); |
| |
| fp = MPFR_MANT (f); |
| fn = MPFR_LIMB_SIZE (f); |
| dif = zn - fn; |
| zp = PTR(z); |
| count_leading_zeros (k, zp[zn-1]); |
| /* because zn >= __gmpfr_emax / BITS_PER_MP_LIMB + 2 |
| and zn * BITS_PER_MP_LIMB >= __gmpfr_emax + BITS_PER_MP_LIMB + 1 |
| and exp = zn * BITS_PER_MP_LIMB - k > __gmpfr_emax */ |
| |
| /* now zn <= MPFR_EMAX_MAX / BITS_PER_MP_LIMB + 1 |
| thus zn * BITS_PER_MP_LIMB <= MPFR_EMAX_MAX + BITS_PER_MP_LIMB |
| and exp = zn * BITS_PER_MP_LIMB - k |
| <= MPFR_EMAX_MAX + BITS_PER_MP_LIMB */ |
| exp = (mp_prec_t) zn * BITS_PER_MP_LIMB - k; |
| /* The exponent will be exp or exp + 1 (due to rounding) */ |
| if (MPFR_UNLIKELY (exp > __gmpfr_emax)) |
| return mpfr_overflow (f, rnd_mode, sign_z); |
| if (MPFR_UNLIKELY (exp + 1 < __gmpfr_emin)) |
| return mpfr_underflow(f, rnd_mode == GMP_RNDN ? GMP_RNDZ : rnd_mode, |
| sign_z); |
| |
| if (MPFR_LIKELY (dif >= 0)) |
| { |
| mp_limb_t rb, sb, ulp; |
| int sh; |
| |
| /* number has to be truncated */ |
| if (MPFR_LIKELY (k != 0)) |
| { |
| mpn_lshift (fp, &zp[dif], fn, k); |
| if (MPFR_LIKELY (dif > 0)) |
| fp[0] |= zp[dif - 1] >> (BITS_PER_MP_LIMB - k); |
| } |
| else |
| MPN_COPY (fp, zp + dif, fn); |
| |
| /* Compute Rounding Bit and Sticky Bit */ |
| MPFR_UNSIGNED_MINUS_MODULO (sh, MPFR_PREC (f) ); |
| if (MPFR_LIKELY (sh != 0)) |
| { |
| mp_limb_t mask = MPFR_LIMB_ONE << (sh-1); |
| mp_limb_t limb = fp[0]; |
| rb = limb & mask; |
| sb = limb & (mask-1); |
| ulp = 2*mask; |
| fp[0] = limb & ~(ulp-1); |
| } |
| else /* sh == 0 */ |
| { |
| mp_limb_t mask = MPFR_LIMB_ONE << (BITS_PER_MP_LIMB - 1 - k); |
| if (MPFR_LIKELY (dif > 0)) |
| { |
| rb = zp[--dif] & mask; |
| sb = zp[dif] & (mask-1); |
| } |
| else |
| rb = sb = 0; |
| k = 0; |
| ulp = MPFR_LIMB_ONE; |
| } |
| if (MPFR_UNLIKELY (sb == 0) && MPFR_LIKELY (dif > 0)) |
| { |
| sb = zp[--dif]; |
| if (MPFR_LIKELY (k != 0)) |
| sb &= MPFR_LIMB_MASK (BITS_PER_MP_LIMB - k); |
| if (MPFR_UNLIKELY (sb == 0) && MPFR_LIKELY (dif > 0)) |
| do { |
| sb = zp[--dif]; |
| } while (dif > 0 && sb == 0); |
| } |
| |
| /* Rounding */ |
| if (MPFR_LIKELY (rnd_mode == GMP_RNDN)) |
| { |
| if (rb == 0 || MPFR_UNLIKELY (sb == 0 && (fp[0] & ulp) == 0)) |
| goto trunc; |
| else |
| goto addoneulp; |
| } |
| else /* Not Nearest */ |
| { |
| if (MPFR_LIKELY (MPFR_IS_LIKE_RNDZ (rnd_mode, sign_z < 0)) |
| || MPFR_UNLIKELY ( (sb|rb) == 0 )) |
| goto trunc; |
| else |
| goto addoneulp; |
| } |
| |
| trunc: |
| inex = MPFR_LIKELY ((sb | rb) != 0) ? -1 : 0; |
| goto end; |
| |
| addoneulp: |
| inex = 1; |
| if (MPFR_UNLIKELY (mpn_add_1 (fp, fp, fn, ulp))) |
| { |
| /* Pow 2 case */ |
| if (MPFR_UNLIKELY (exp == __gmpfr_emax)) |
| return mpfr_overflow (f, rnd_mode, sign_z); |
| exp ++; |
| fp[fn-1] = MPFR_LIMB_HIGHBIT; |
| } |
| end: |
| (void) 0; |
| } |
| else /* dif < 0: Mantissa F is strictly bigger than z's one */ |
| { |
| if (MPFR_LIKELY (k != 0)) |
| mpn_lshift (fp - dif, zp, zn, k); |
| else |
| MPN_COPY (fp - dif, zp, zn); |
| /* fill with zeroes */ |
| MPN_ZERO (fp, -dif); |
| inex = 0; /* result is exact */ |
| } |
| |
| if (MPFR_UNLIKELY (exp < __gmpfr_emin)) |
| { |
| if (rnd_mode == GMP_RNDN && inex == 0 && mpfr_powerof2_raw (f)) |
| rnd_mode = GMP_RNDZ; |
| return mpfr_underflow(f, rnd_mode, sign_z); |
| } |
| |
| MPFR_SET_EXP (f, exp); |
| MPFR_SET_SIGN (f, sign_z); |
| MPFR_RET (inex*sign_z); |
| } |
| |