| 1 | /* |
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| 2 | * ==================================================== |
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| 3 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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| 4 | * |
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| 5 | * Developed at SunPro, a Sun Microsystems, Inc. business. |
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| 6 | * Permission to use, copy, modify, and distribute this |
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| 7 | * software is freely granted, provided that this notice |
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| 8 | * is preserved. |
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| 9 | * ==================================================== |
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| 10 | */ |
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| 11 | |
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| 12 | /* |
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| 13 | * rint(x) |
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| 14 | * Return x rounded to integral value according to the prevailing |
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| 15 | * rounding mode. |
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| 16 | * Method: |
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| 17 | * Using floating addition. |
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| 18 | * Exception: |
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| 19 | * Inexact flag raised if x not equal to rint(x). |
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| 20 | */ |
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| 21 | |
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| 22 | #define NO_MATH_REDIRECT |
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| 23 | #include <math.h> |
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| 24 | #include <math_private.h> |
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| 25 | #include <libm-alias-double.h> |
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| 26 | #include <math-use-builtins.h> |
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| 27 | |
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| 28 | double |
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| 29 | __rint (double x) |
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| 30 | { |
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| 31 | #if USE_RINT_BUILTIN |
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| 32 | return __builtin_rint (x); |
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| 33 | #else |
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| 34 | /* Use generic implementation. */ |
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| 35 | static const double |
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| 36 | TWO52[2] = { |
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| 37 | 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */ |
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| 38 | -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */ |
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| 39 | }; |
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| 40 | int64_t i0, sx; |
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| 41 | int32_t j0; |
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| 42 | EXTRACT_WORDS64 (i0, x); |
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| 43 | sx = (i0 >> 63) & 1; |
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| 44 | j0 = ((i0 >> 52) & 0x7ff) - 0x3ff; |
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| 45 | if (j0 < 52) |
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| 46 | { |
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| 47 | if (j0 < 0) |
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| 48 | { |
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| 49 | double w = TWO52[sx] + x; |
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| 50 | double t = w - TWO52[sx]; |
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| 51 | EXTRACT_WORDS64 (i0, t); |
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| 52 | INSERT_WORDS64 (t, (i0 & UINT64_C (0x7fffffffffffffff)) |
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| 53 | | (sx << 63)); |
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| 54 | return t; |
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| 55 | } |
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| 56 | } |
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| 57 | else |
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| 58 | { |
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| 59 | if (j0 == 0x400) |
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| 60 | return x + x; /* inf or NaN */ |
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| 61 | else |
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| 62 | return x; /* x is integral */ |
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| 63 | } |
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| 64 | double w = TWO52[sx] + x; |
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| 65 | return w - TWO52[sx]; |
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| 66 | #endif /* ! USE_RINT_BUILTIN */ |
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| 67 | } |
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| 68 | #ifndef __rint |
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| 69 | libm_alias_double (__rint, rint) |
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| 70 | #endif |
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| 71 | |
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