Last change
on this file was 389, checked in by coas-nagasima, 5 years ago |
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[388] | 1 | #include <limits.h>
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| 2 | #include <fenv.h>
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| 3 | #include "libm.h"
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| 4 |
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| 5 | /*
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| 6 | If the result cannot be represented (overflow, nan), then
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| 7 | lrint raises the invalid exception.
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| 8 |
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| 9 | Otherwise if the input was not an integer then the inexact
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| 10 | exception is raised.
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| 11 |
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| 12 | C99 is a bit vague about whether inexact exception is
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| 13 | allowed to be raised when invalid is raised.
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| 14 | (F.9 explicitly allows spurious inexact exceptions, F.9.6.5
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| 15 | does not make it clear if that rule applies to lrint, but
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| 16 | IEEE 754r 7.8 seems to forbid spurious inexact exception in
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| 17 | the ineger conversion functions)
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| 18 |
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| 19 | So we try to make sure that no spurious inexact exception is
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| 20 | raised in case of an overflow.
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| 21 |
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| 22 | If the bit size of long > precision of double, then there
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| 23 | cannot be inexact rounding in case the result overflows,
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| 24 | otherwise LONG_MAX and LONG_MIN can be represented exactly
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| 25 | as a double.
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| 26 | */
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| 27 |
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| 28 | #if LONG_MAX < 1U<<53 && defined(FE_INEXACT)
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| 29 | long lrint(double x)
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| 30 | {
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| 31 | #pragma STDC FENV_ACCESS ON
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| 32 | int e;
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| 33 |
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| 34 | e = fetestexcept(FE_INEXACT);
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| 35 | x = rint(x);
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| 36 | if (!e && (x > LONG_MAX || x < LONG_MIN))
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| 37 | feclearexcept(FE_INEXACT);
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| 38 | /* conversion */
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| 39 | return x;
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| 40 | }
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| 41 | #else
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| 42 | long lrint(double x)
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| 43 | {
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| 44 | return rint(x);
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| 45 | }
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| 46 | #endif
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