diff options
Diffstat (limited to 'rts/gmp/mpn/pa64/udiv_qrnnd.c')
-rw-r--r-- | rts/gmp/mpn/pa64/udiv_qrnnd.c | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/rts/gmp/mpn/pa64/udiv_qrnnd.c b/rts/gmp/mpn/pa64/udiv_qrnnd.c new file mode 100644 index 0000000000..1c9fe084db --- /dev/null +++ b/rts/gmp/mpn/pa64/udiv_qrnnd.c @@ -0,0 +1,111 @@ +/* +Copyright (C) 1999, 2000 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 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 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 Lesser General Public +License for more details. + +You should have received a copy of the GNU Lesser 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" + +#define TWO64 18446744073709551616.0 + +mp_limb_t +#if __STDC__ +__MPN(udiv_qrnnd) (mp_limb_t n1, mp_limb_t n0, mp_limb_t d, mp_limb_t *r) +#else +__MPN(udiv_qrnnd) (n1, n0, d, r) + mp_limb_t n1; + mp_limb_t n0; + mp_limb_t d; + mp_limb_t *r; +#endif +{ + mp_limb_t q1, q2, q; + mp_limb_t p1, p0; + double di, dq; + + di = 1.0 / d; + + /* Generate upper 53 bits of quotient. Be careful here; the `double' + quotient may be rounded to 2^64 which we cannot safely convert back + to a 64-bit integer. */ + dq = (TWO64 * (double) n1 + (double) n0) * di; + if (dq >= TWO64) + q1 = 0xfffffffffffff800LL; + else + q1 = (mp_limb_t) dq; + + /* Multiply back in order to compare the product to the dividend. */ + umul_ppmm (p1, p0, q1, d); + + /* Was the 53-bit quotient greater that our sought quotient? Test the + sign of the partial remainder to find out. */ + if (n1 < p1 || (n1 == p1 && n0 < p0)) + { + /* 53-bit quotient too large. Partial remainder is negative. + Compute the absolute value of the remainder in n1,,n0. */ + n1 = p1 - (n1 + (p0 < n0)); + n0 = p0 - n0; + + /* Now use the partial remainder as new dividend to compute more bits of + quotient. This is an adjustment for the one we got previously. */ + q2 = (mp_limb_t) ((TWO64 * (double) n1 + (double) n0) * di); + umul_ppmm (p1, p0, q2, d); + + q = q1 - q2; + if (n1 < p1 || (n1 == p1 && n0 <= p0)) + { + n0 = p0 - n0; + } + else + { + n0 = p0 - n0; + n0 += d; + q--; + } + } + else + { + n1 = n1 - (p1 + (n0 < p0)); + n0 = n0 - p0; + + q2 = (mp_limb_t) ((TWO64 * (double) n1 + (double) n0) * di); + umul_ppmm (p1, p0, q2, d); + + q = q1 + q2; + if (n1 < p1 || (n1 == p1 && n0 < p0)) + { + n0 = n0 - p0; + n0 += d; + q--; + } + else + { + n0 = n0 - p0; + if (n0 >= d) + { + n0 -= d; + q++; + } + } + } + + *r = n0; + return q; +} |