1 files changed, 36 insertions, 0 deletions
diff --git a/lib/libm/coshf.c b/lib/libm/coshf.c
new file mode 100644
index 00000000..451e6928
--- /dev/null
+++ b/lib/libm/coshf.c
@@ -0,0 +1,36 @@
+#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, 1.0f);
+	return t;
+}