From bd5969fc876a10b18613302db7087ef3c40f18e1 Mon Sep 17 00:00:00 2001 From: Ian Moffett Date: Thu, 7 Mar 2024 17:28:00 -0500 Subject: lib: Add mlibc Signed-off-by: Ian Moffett --- lib/mlibc/options/ansi/musl-generic-math/lrint.c | 46 ++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 lib/mlibc/options/ansi/musl-generic-math/lrint.c (limited to 'lib/mlibc/options/ansi/musl-generic-math/lrint.c') diff --git a/lib/mlibc/options/ansi/musl-generic-math/lrint.c b/lib/mlibc/options/ansi/musl-generic-math/lrint.c new file mode 100644 index 0000000..bdca8b7 --- /dev/null +++ b/lib/mlibc/options/ansi/musl-generic-math/lrint.c @@ -0,0 +1,46 @@ +#include +#include +#include "libm.h" + +/* +If the result cannot be represented (overflow, nan), then +lrint raises the invalid exception. + +Otherwise if the input was not an integer then the inexact +exception is raised. + +C99 is a bit vague about whether inexact exception is +allowed to be raised when invalid is raised. +(F.9 explicitly allows spurious inexact exceptions, F.9.6.5 +does not make it clear if that rule applies to lrint, but +IEEE 754r 7.8 seems to forbid spurious inexact exception in +the ineger conversion functions) + +So we try to make sure that no spurious inexact exception is +raised in case of an overflow. + +If the bit size of long > precision of double, then there +cannot be inexact rounding in case the result overflows, +otherwise LONG_MAX and LONG_MIN can be represented exactly +as a double. +*/ + +#if LONG_MAX < 1U<<53 && defined(FE_INEXACT) +long lrint(double x) +{ + #pragma STDC FENV_ACCESS ON + int e; + + e = fetestexcept(FE_INEXACT); + x = rint(x); + if (!e && (x > LONG_MAX || x < LONG_MIN)) + feclearexcept(FE_INEXACT); + /* conversion */ + return x; +} +#else +long lrint(double x) +{ + return rint(x); +} +#endif -- cgit v1.2.3