math: use double_t for temporaries to avoid stores on i386

[musl] / src / math / asinf.c

diff --git a/src/math/asinf.c b/src/math/asinf.c
index 729dd37..51fe6c6 100644 (file)
--- a/src/math/asinf.c
+++ b/src/math/asinf.c
@@ -12,53 +12,51 @@
  * is preserved.
  * ====================================================
  */
-
 #include "libm.h"
 
+static const double
+pio2 = 1.570796326794896558e+00;
+
 static const float
-one =  1.0000000000e+00, /* 0x3F800000 */
-huge = 1.000e+30,
 /* coefficients for R(x^2) */
 pS0 =  1.6666586697e-01,
 pS1 = -4.2743422091e-02,
 pS2 = -8.6563630030e-03,
 qS1 = -7.0662963390e-01;
 
-static const double
-pio2 = 1.570796326794896558e+00;
+static float R(float z)
+{
+       float_t p, q;
+       p = z*(pS0+z*(pS1+z*pS2));
+       q = 1.0f+z*qS1;
+       return p/q;
+}
 
 float asinf(float x)
 {
        double s;
-       float t,w,p,q;
-       int32_t hx,ix;
+       float z;
+       uint32_t hx,ix;
 
        GET_FLOAT_WORD(hx, x);
        ix = hx & 0x7fffffff;
        if (ix >= 0x3f800000) {  /* |x| >= 1 */
                if (ix == 0x3f800000)  /* |x| == 1 */
-                       return x*pio2;  /* asin(+-1) = +-pi/2 with inexact */
-               return (x-x)/(x-x);  /* asin(|x|>1) is NaN */
-       } else if (ix < 0x3f000000) {  /* |x|<0.5 */
+                       return x*pio2 + 0x1p-120f;  /* asin(+-1) = +-pi/2 with inexact */
+               return 0/(x-x);  /* asin(|x|>1) is NaN */
+       }
+       if (ix < 0x3f000000) {  /* |x| < 0.5 */
                if (ix < 0x39800000) {  /* |x| < 2**-12 */
-                       if (huge+x > one)
-                               return x; /* return x with inexact if x!=0 */
+                       FORCE_EVAL(x + 0x1p120f);
+                       return x; /* return x with inexact if x!=0 */
                }
-               t = x*x;
-               p = t*(pS0+t*(pS1+t*pS2));
-               q = one+t*qS1;
-               w = p/q;
-               return x + x*w;
+               return x + x*R(x*x);
        }
        /* 1 > |x| >= 0.5 */
-       w = one - fabsf(x);
-       t = w*(float)0.5;
-       p = t*(pS0+t*(pS1+t*pS2));
-       q = one+t*qS1;
-       s = sqrt(t);
-       w = p/q;
-       t = pio2-2.0*(s+s*w);
-       if (hx > 0)
-               return t;
-       return -t;
+       z = (1 - fabsf(x))*0.5f;
+       s = sqrt(z);
+       x = pio2 - 2*(s+s*R(z));
+       if (hx >> 31)
+               return -x;
+       return x;
 }