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