1/* Compute remainder and a congruent to the quotient. 2 Copyright (C) 1997-2018 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997 and 5 Jakub Jelinek <jj@ultra.linux.cz>, 1999. 6 7 The GNU C Library is free software; you can redistribute it and/or 8 modify it under the terms of the GNU Lesser General Public 9 License as published by the Free Software Foundation; either 10 version 2.1 of the License, or (at your option) any later version. 11 12 The GNU C Library is distributed in the hope that it will be useful, 13 but WITHOUT ANY WARRANTY; without even the implied warranty of 14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 15 Lesser General Public License for more details. 16 17 You should have received a copy of the GNU Lesser General Public 18 License along with the GNU C Library; if not, see 19 <http://www.gnu.org/licenses/>. */ 20 21#include "quadmath-imp.h" 22 23static const __float128 zero = 0.0; 24 25 26__float128 27remquoq (__float128 x, __float128 y, int *quo) 28{ 29 int64_t hx,hy; 30 uint64_t sx,lx,ly,qs; 31 int cquo; 32 33 GET_FLT128_WORDS64 (hx, lx, x); 34 GET_FLT128_WORDS64 (hy, ly, y); 35 sx = hx & 0x8000000000000000ULL; 36 qs = sx ^ (hy & 0x8000000000000000ULL); 37 hy &= 0x7fffffffffffffffLL; 38 hx &= 0x7fffffffffffffffLL; 39 40 /* Purge off exception values. */ 41 if ((hy | ly) == 0) 42 return (x * y) / (x * y); /* y = 0 */ 43 if ((hx >= 0x7fff000000000000LL) /* x not finite */ 44 || ((hy >= 0x7fff000000000000LL) /* y is NaN */ 45 && (((hy - 0x7fff000000000000LL) | ly) != 0))) 46 return (x * y) / (x * y); 47 48 if (hy <= 0x7ffbffffffffffffLL) 49 x = fmodq (x, 8 * y); /* now x < 8y */ 50 51 if (((hx - hy) | (lx - ly)) == 0) 52 { 53 *quo = qs ? -1 : 1; 54 return zero * x; 55 } 56 57 x = fabsq (x); 58 y = fabsq (y); 59 cquo = 0; 60 61 if (hy <= 0x7ffcffffffffffffLL && x >= 4 * y) 62 { 63 x -= 4 * y; 64 cquo += 4; 65 } 66 if (hy <= 0x7ffdffffffffffffLL && x >= 2 * y) 67 { 68 x -= 2 * y; 69 cquo += 2; 70 } 71 72 if (hy < 0x0002000000000000LL) 73 { 74 if (x + x > y) 75 { 76 x -= y; 77 ++cquo; 78 if (x + x >= y) 79 { 80 x -= y; 81 ++cquo; 82 } 83 } 84 } 85 else 86 { 87 __float128 y_half = 0.5Q * y; 88 if (x > y_half) 89 { 90 x -= y; 91 ++cquo; 92 if (x >= y_half) 93 { 94 x -= y; 95 ++cquo; 96 } 97 } 98 } 99 100 *quo = qs ? -cquo : cquo; 101 102 /* Ensure correct sign of zero result in round-downward mode. */ 103 if (x == 0) 104 x = 0; 105 if (sx) 106 x = -x; 107 return x; 108} 109