math: finished cosh.c cleanup

[musl] / src / math / coshf.c

diff --git a/src/math/coshf.c b/src/math/coshf.c
index 97318f1..b09f2ee 100644 (file)
--- a/src/math/coshf.c
+++ b/src/math/coshf.c
@@ -1,57 +1,33 @@
-/* origin: FreeBSD /usr/src/lib/msun/src/e_coshf.c */
-/*
- * Conversion to float by Ian Lance Taylor, Cygnus Support, ian@cygnus.com.
- */
-/*
- * ====================================================
- * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
- *
- * Developed at SunPro, a Sun Microsystems, Inc. business.
- * Permission to use, copy, modify, and distribute this
- * software is freely granted, provided that this notice
- * is preserved.
- * ====================================================
- */
-
 #include "libm.h"
 
-static const float huge = 1.0e30;
-
 float coshf(float x)
 {
-       float t, w;
-       int32_t ix;
-
-       GET_FLOAT_WORD(ix, x);
-       ix &= 0x7fffffff;
-
-       /* x is INF or NaN */
-       if (ix >= 0x7f800000)
-               return x*x;
-
-       /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
-       if (ix < 0x3eb17218) {
-               t = expm1f(fabsf(x));
-               w = 1.0f+t;
-               if (ix<0x39800000)
-                       return 1.0f;  /* cosh(tiny) = 1 */
-               return 1.0f + (t*t)/(w+w);
+       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| in [0.5*ln2,9], return (exp(|x|)+1/exp(|x|))/2; */
-       if (ix < 0x41100000) {
-               t = expf(fabsf(x));
-               return 0.5f*t + 0.5f/t;
+       /* |x| < log(FLT_MAX) */
+       if (w < 0x42b17217) {
+               t = expf(x);
+               return 0.5f*(t + 1/t);
        }
 
-       /* |x| in [9, log(maxfloat)] return 0.5f*exp(|x|) */
-       if (ix < 0x42b17217)
-               return 0.5f*expf(fabsf(x));
-
-       /* |x| in [log(maxfloat), overflowthresold] */
-       if (ix <= 0x42b2d4fc)
-               return __expo2f(fabsf(x));
-
-       /* |x| > overflowthresold, cosh(x) overflow */
-       return huge*huge;
+       /* |x| > log(FLT_MAX) or nan */
+       t = __expo2f(x);
+       return t;
 }