diff options
author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 13:54:38 +0000 |
---|---|---|
committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 13:54:38 +0000 |
commit | 8c1ab65c0f548d20b7f177bdb736daaf603340e1 (patch) | |
tree | df55b7e75bf43f2bf500845b105afe3ac3a5157e /libc-top-half/musl/src/math/lrint.c | |
parent | Initial commit. (diff) | |
download | wasi-libc-upstream/0.0_git20221206.8b7148f.tar.xz wasi-libc-upstream/0.0_git20221206.8b7148f.zip |
Adding upstream version 0.0~git20221206.8b7148f.upstream/0.0_git20221206.8b7148f
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'libc-top-half/musl/src/math/lrint.c')
-rw-r--r-- | libc-top-half/musl/src/math/lrint.c | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/libc-top-half/musl/src/math/lrint.c b/libc-top-half/musl/src/math/lrint.c new file mode 100644 index 0000000..ddee7a0 --- /dev/null +++ b/libc-top-half/musl/src/math/lrint.c @@ -0,0 +1,72 @@ +#include <limits.h> +#include <fenv.h> +#include <math.h> +#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) +#include <float.h> +#include <stdint.h> +#if FLT_EVAL_METHOD==0 || FLT_EVAL_METHOD==1 +#define EPS DBL_EPSILON +#elif FLT_EVAL_METHOD==2 +#define EPS LDBL_EPSILON +#endif +#ifdef __GNUC__ +/* avoid stack frame in lrint */ +__attribute__((noinline)) +#endif +static long lrint_slow(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; +} + +long lrint(double x) +{ + uint32_t abstop = asuint64(x)>>32 & 0x7fffffff; + uint64_t sign = asuint64(x) & (1ULL << 63); + + if (abstop < 0x41dfffff) { + /* |x| < 0x7ffffc00, no overflow */ + double_t toint = asdouble(asuint64(1/EPS) | sign); + double_t y = x + toint - toint; + return (long)y; + } + return lrint_slow(x); +} +#else +long lrint(double x) +{ + return rint(x); +} +#endif |