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

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

1 files changed, 33 insertions, 0 deletions

diff --git a/lib/libc/src/musl-math/coshf.c b/lib/libc/src/musl-math/coshf.c
new file mode 100644
index 0000000..b09f2ee
--- /dev/null
+++ b/lib/libc/src/musl-math/coshf.c
@@ -0,0 +1,33 @@
+#include "libm.h"
+
+float coshf(float x)
+{
+	union {float f; uint32_t i;} u = {.f = x};
+	uint32_t w;
+	float t;
+
+	/* |x| */
+	u.i &= 0x7fffffff;
+	x = u.f;
+	w = u.i;
+
+	/* |x| < log(2) */
+	if (w < 0x3f317217) {
+		if (w < 0x3f800000 - (12<<23)) {
+			FORCE_EVAL(x + 0x1p120f);
+			return 1;
+		}
+		t = expm1f(x);
+		return 1 + t*t/(2*(1+t));
+	}
+
+	/* |x| < log(FLT_MAX) */
+	if (w < 0x42b17217) {
+		t = expf(x);
+		return 0.5f*(t + 1/t);
+	}
+
+	/* |x| > log(FLT_MAX) or nan */
+	t = __expo2f(x);
+	return t;
+}