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

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

1 files changed, 11 insertions, 0 deletions

diff --git a/lib/libc/src/musl-math/__fpclassify.c b/lib/libc/src/musl-math/__fpclassify.c
new file mode 100644
index 0000000..f7c0e2d
--- /dev/null
+++ b/lib/libc/src/musl-math/__fpclassify.c
@@ -0,0 +1,11 @@
+#include <math.h>
+#include <stdint.h>
+
+int __fpclassify(double x)
+{
+	union {double f; uint64_t i;} u = {x};
+	int e = u.i>>52 & 0x7ff;
+	if (!e) return u.i<<1 ? FP_SUBNORMAL : FP_ZERO;
+	if (e==0x7ff) return u.i<<12 ? FP_NAN : FP_INFINITE;
+	return FP_NORMAL;
+}