1 /* Truncate argument to nearest integral value not larger than the argument. 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 <math-use-builtins.h> 25 26 27 double __trunc(double x)28__trunc (double x) 29 { 30 #if USE_TRUNC_BUILTIN 31 return __builtin_trunc (x); 32 #else 33 /* Use generic implementation. */ 34 int64_t i0, j0; 35 int64_t sx; 36 37 EXTRACT_WORDS64 (i0, x); 38 sx = i0 & UINT64_C (0x8000000000000000); 39 j0 = ((i0 >> 52) & 0x7ff) - 0x3ff; 40 if (j0 < 52) 41 { 42 if (j0 < 0) 43 /* The magnitude of the number is < 1 so the result is +-0. */ 44 INSERT_WORDS64 (x, sx); 45 else 46 INSERT_WORDS64 (x, sx | (i0 & ~(UINT64_C (0x000fffffffffffff) >> j0))); 47 } 48 else 49 { 50 if (j0 == 0x400) 51 /* x is inf or NaN. */ 52 return x + x; 53 } 54 55 return x; 56 #endif /* ! USE_TRUNC_BUILTIN */ 57 } 58 #ifndef __trunc 59 libm_alias_double (__trunc, trunc) 60 #endif 61