diff options
Diffstat (limited to 'gnu/lib/libgmp/mpq/get_d.c')
| -rw-r--r-- | gnu/lib/libgmp/mpq/get_d.c | 151 |
1 files changed, 0 insertions, 151 deletions
diff --git a/gnu/lib/libgmp/mpq/get_d.c b/gnu/lib/libgmp/mpq/get_d.c deleted file mode 100644 index cb4e800..0000000 --- a/gnu/lib/libgmp/mpq/get_d.c +++ /dev/null @@ -1,151 +0,0 @@ -/* double mpq_get_d (mpq_t src) -- Return the double approximation to SRC. - -Copyright (C) 1995, 1996 Free Software Foundation, Inc. - -This file is part of the GNU MP Library. - -The GNU MP Library is free software; you can redistribute it and/or modify -it under the terms of the GNU Library General Public License as published by -the Free Software Foundation; either version 2 of the License, or (at your -option) any later version. - -The GNU MP 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 Library General Public -License for more details. - -You should have received a copy of the GNU Library General Public License -along with the GNU MP 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. */ - -#include "gmp.h" -#include "gmp-impl.h" -#include "longlong.h" - -/* Algorithm: - 1. Develop >= n bits of src.num / src.den, where n is the number of bits - in a double. This (partial) division will use all bits from the - denominator. - 2. Use the remainder to determine how to round the result. - 3. Assign the integral result to a temporary double. - 4. Scale the temporary double, and return the result. - - An alternative algorithm, that would be faster: - 0. Let n be somewhat larger than the number of significant bits in a double. - 1. Extract the most significant n bits of the denominator, and an equal - number of bits from the numerator. - 2. Interpret the extracted numbers as integers, call them a and b - respectively, and develop n bits of the fractions ((a + 1) / b) and - (a / (b + 1)) using mpn_divrem. - 3. If the computed values are identical UP TO THE POSITION WE CARE ABOUT, - we are done. If they are different, repeat the algorithm from step 1, - but first let n = n * 2. - 4. If we end up using all bits from the numerator and denominator, fall - back to the first algorithm above. - 5. Just to make life harder, The computation of a + 1 and b + 1 above - might give carry-out... Needs special handling. It might work to - subtract 1 in both cases instead. -*/ - -double -#if __STDC__ -mpq_get_d (const MP_RAT *src) -#else -mpq_get_d (src) - const MP_RAT *src; -#endif -{ - mp_ptr np, dp; - mp_ptr rp; - mp_size_t nsize = src->_mp_num._mp_size; - mp_size_t dsize = src->_mp_den._mp_size; - mp_size_t qsize, rsize; - mp_size_t sign_quotient = nsize ^ dsize; - unsigned normalization_steps; - mp_limb_t qlimb; -#define N_QLIMBS (1 + (sizeof (double) + BYTES_PER_MP_LIMB-1) / BYTES_PER_MP_LIMB) - mp_limb_t qp[N_QLIMBS + 1]; - TMP_DECL (marker); - - if (nsize == 0) - return 0.0; - - TMP_MARK (marker); - nsize = ABS (nsize); - dsize = ABS (dsize); - np = src->_mp_num._mp_d; - dp = src->_mp_den._mp_d; - - rsize = dsize + N_QLIMBS; - rp = (mp_ptr) TMP_ALLOC ((rsize + 1) * BYTES_PER_MP_LIMB); - - count_leading_zeros (normalization_steps, dp[dsize - 1]); - - /* Normalize the denominator, i.e. make its most significant bit set by - shifting it NORMALIZATION_STEPS bits to the left. Also shift the - numerator the same number of steps (to keep the quotient the same!). */ - if (normalization_steps != 0) - { - mp_ptr tp; - mp_limb_t nlimb; - - /* Shift up the denominator setting the most significant bit of - the most significant limb. Use temporary storage not to clobber - the original contents of the denominator. */ - tp = (mp_ptr) TMP_ALLOC (dsize * BYTES_PER_MP_LIMB); - mpn_lshift (tp, dp, dsize, normalization_steps); - dp = tp; - - if (rsize > nsize) - { - MPN_ZERO (rp, rsize - nsize); - nlimb = mpn_lshift (rp + (rsize - nsize), - np, nsize, normalization_steps); - } - else - { - nlimb = mpn_lshift (rp, np + (nsize - rsize), - rsize, normalization_steps); - } - if (nlimb != 0) - { - rp[rsize] = nlimb; - rsize++; - } - } - else - { - if (rsize > nsize) - { - MPN_ZERO (rp, rsize - nsize); - MPN_COPY (rp + (rsize - nsize), np, nsize); - } - else - { - MPN_COPY (rp, np + (nsize - rsize), rsize); - } - } - - qlimb = mpn_divmod (qp, rp, rsize, dp, dsize); - qsize = rsize - dsize; - if (qlimb) - { - qp[qsize] = qlimb; - qsize++; - } - - { - double res; - mp_size_t i; - - res = qp[qsize - 1]; - for (i = qsize - 2; i >= 0; i--) - res = res * MP_BASE_AS_DOUBLE + qp[i]; - - res = __gmp_scale2 (res, BITS_PER_MP_LIMB * (nsize - dsize - N_QLIMBS)); - - TMP_FREE (marker); - return sign_quotient >= 0 ? res : -res; - } -} |
