usr: libc: Add math.h + musl math impl port

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 36 insertions, 0 deletions

diff --git a/lib/libc/src/musl-math/lrintl.c b/lib/libc/src/musl-math/lrintl.c
new file mode 100644
index 0000000..b2a8106
--- /dev/null
+++ b/lib/libc/src/musl-math/lrintl.c
@@ -0,0 +1,36 @@
+#include <limits.h>
+#include <fenv.h>
+#include "libm.h"
+
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long lrintl(long double x)
+{
+	return lrint(x);
+}
+#elif defined(FE_INEXACT)
+/*
+see comments in lrint.c
+
+Note that if LONG_MAX == 0x7fffffffffffffff && LDBL_MANT_DIG == 64
+then x == 2**63 - 0.5 is the only input that overflows and
+raises inexact (with tonearest or upward rounding mode)
+*/
+long lrintl(long double x)
+{
+	#pragma STDC FENV_ACCESS ON
+	int e;
+
+	e = fetestexcept(FE_INEXACT);
+	x = rintl(x);
+	if (!e && (x > LONG_MAX || x < LONG_MIN))
+		feclearexcept(FE_INEXACT);
+	/* conversion */
+	return x;
+}
+#else
+long lrintl(long double x)
+{
+	return rintl(x);
+}
+#endif