| 1 | /* Round double to integer away from zero. |
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| 2 | Copyright (C) 2011-2022 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 | /* Based on a version which carries the following copyright: */ |
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| 20 | |
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| 21 | /* |
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| 22 | * ==================================================== |
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| 23 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 24 | * |
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| 25 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 26 | * Permission to use, copy, modify, and distribute this |
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| 27 | * software is freely granted, provided that this notice |
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| 28 | * is preserved. |
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| 29 | * ==================================================== |
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| 30 | */ |
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| 31 | |
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| 32 | #define NO_MATH_REDIRECT |
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| 33 | #include <math.h> |
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| 34 | #include <math_private.h> |
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| 35 | #include <stdint.h> |
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| 36 | #include <libm-alias-double.h> |
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| 37 | #include <math-use-builtins.h> |
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| 38 | |
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| 39 | /* |
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| 40 | * floor(x) |
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| 41 | * Return x rounded toward -inf to integral value |
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| 42 | * Method: |
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| 43 | * Bit twiddling. |
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| 44 | */ |
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| 45 | |
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| 46 | |
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| 47 | double |
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| 48 | __floor (double x) |
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| 49 | { |
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| 50 | #if USE_FLOOR_BUILTIN |
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| 51 | return __builtin_floor (x); |
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| 52 | #else |
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| 53 | /* Use generic implementation. */ |
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| 54 | int64_t i0; |
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| 55 | EXTRACT_WORDS64 (i0, x); |
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| 56 | int32_t j0 = ((i0 >> 52) & 0x7ff) - 0x3ff; |
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| 57 | if (__glibc_likely (j0 < 52)) |
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| 58 | { |
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| 59 | if (j0 < 0) |
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| 60 | { |
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| 61 | /* return 0 * sign (x) if |x| < 1 */ |
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| 62 | if (i0 >= 0) |
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| 63 | i0 = 0; |
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| 64 | else if ((i0 & 0x7fffffffffffffffl) != 0) |
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| 65 | i0 = 0xbff0000000000000l; |
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| 66 | } |
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| 67 | else |
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| 68 | { |
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| 69 | uint64_t i = 0x000fffffffffffffl >> j0; |
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| 70 | if ((i0 & i) == 0) |
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| 71 | return x; /* x is integral */ |
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| 72 | if (i0 < 0) |
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| 73 | i0 += 0x0010000000000000l >> j0; |
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| 74 | i0 &= ~i; |
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| 75 | } |
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| 76 | INSERT_WORDS64 (x, i0); |
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| 77 | } |
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| 78 | else if (j0 == 0x400) |
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| 79 | return x + x; /* inf or NaN */ |
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| 80 | return x; |
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| 81 | #endif /* ! USE_FLOOR_BUILTIN */ |
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| 82 | } |
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| 83 | #ifndef __floor |
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| 84 | libm_alias_double (__floor, floor) |
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| 85 | #endif |
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| 86 | |
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