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

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

1 files changed, 16 insertions, 0 deletions

diff --git a/lib/libc/src/musl-math/logbl.c b/lib/libc/src/musl-math/logbl.c
new file mode 100644
index 0000000..962973a
--- /dev/null
+++ b/lib/libc/src/musl-math/logbl.c
@@ -0,0 +1,16 @@
+#include <math.h>
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double logbl(long double x)
+{
+	return logb(x);
+}
+#else
+long double logbl(long double x)
+{
+	if (!isfinite(x))
+		return x * x;
+	if (x == 0)
+		return -1/(x*x);
+	return ilogbl(x);
+}
+#endif