1 /* Round double to integer away from zero. 2 Copyright (C) 1997-2022 Free Software Foundation, Inc. 3 This file is part of the GNU C Library. 4 5 The GNU C Library is free software; you can redistribute it and/or 6 modify it under the terms of the GNU Lesser General Public 7 License as published by the Free Software Foundation; either 8 version 2.1 of the License, or (at your option) any later version. 9 10 The GNU C Library is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 13 Lesser General Public License for more details. 14 15 You should have received a copy of the GNU Lesser General Public 16 License along with the GNU C Library; if not, see 17 <https://www.gnu.org/licenses/>. */ 18 19 #define NO_MATH_REDIRECT 20 #include <math.h> 21 22 #include <math_private.h> 23 #include <libm-alias-double.h> 24 #include <stdint.h> 25 #include <math-use-builtins.h> 26 27 28 double __round(double x)29__round (double x) 30 { 31 #if USE_ROUND_BUILTIN 32 return __builtin_round (x); 33 #else 34 /* Use generic implementation. */ 35 int64_t i0, j0; 36 37 EXTRACT_WORDS64 (i0, x); 38 j0 = ((i0 >> 52) & 0x7ff) - 0x3ff; 39 if (__glibc_likely (j0 < 52)) 40 { 41 if (j0 < 0) 42 { 43 i0 &= UINT64_C (0x8000000000000000); 44 if (j0 == -1) 45 i0 |= UINT64_C (0x3ff0000000000000); 46 } 47 else 48 { 49 uint64_t i = UINT64_C (0x000fffffffffffff) >> j0; 50 if ((i0 & i) == 0) 51 /* X is integral. */ 52 return x; 53 54 i0 += UINT64_C (0x0008000000000000) >> j0; 55 i0 &= ~i; 56 } 57 } 58 else 59 { 60 if (j0 == 0x400) 61 /* Inf or NaN. */ 62 return x + x; 63 else 64 return x; 65 } 66 67 INSERT_WORDS64 (x, i0); 68 return x; 69 #endif /* ! USE_ROUND_BUILTIN */ 70 } 71 libm_alias_double (__round, round) 72