Add a "fork" of musl as //fusl.

fusl/src/math/coshf.c

+#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;
+}