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