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

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

1 files changed, 34 insertions, 0 deletions

diff --git a/lib/libc/src/musl-math/floorl.c b/lib/libc/src/musl-math/floorl.c
new file mode 100644
index 0000000..16aaec4
--- /dev/null
+++ b/lib/libc/src/musl-math/floorl.c
@@ -0,0 +1,34 @@
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double floorl(long double x)
+{
+	return floor(x);
+}
+#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
+
+static const long double toint = 1/LDBL_EPSILON;
+
+long double floorl(long double x)
+{
+	union ldshape u = {x};
+	int e = u.i.se & 0x7fff;
+	long double y;
+
+	if (e >= 0x3fff+LDBL_MANT_DIG-1 || x == 0)
+		return x;
+	/* y = int(x) - x, where int(x) is an integer neighbor of x */
+	if (u.i.se >> 15)
+		y = x - toint + toint - x;
+	else
+		y = x + toint - toint - x;
+	/* special case because of non-nearest rounding modes */
+	if (e <= 0x3fff-1) {
+		FORCE_EVAL(y);
+		return u.i.se >> 15 ? -1 : 0;
+	}
+	if (y > 0)
+		return x + y - 1;
+	return x + y;
+}
+#endif