math: tan cleanups

[musl] / src / math / tanl.c

diff --git a/src/math/tanl.c b/src/math/tanl.c
index 0194eaf..3b51e01 100644 (file)
--- a/src/math/tanl.c
+++ b/src/math/tanl.c
@@ -41,42 +41,27 @@ long double tanl(long double x)
 long double tanl(long double x)
 {
        union IEEEl2bits z;
 long double tanl(long double x)
 {
        union IEEEl2bits z;

-       int e0, s;

        long double y[2];
        long double y[2];

-       long double hi, lo;
+       unsigned n;

 
        z.e = x;
 
        z.e = x;

-       s = z.bits.sign;

        z.bits.sign = 0;
 
        z.bits.sign = 0;
 

-       /* If x = +-0 or x is subnormal, then tan(x) = x. */
-       if (z.bits.exp == 0)
-               return x;
-

        /* If x = NaN or Inf, then tan(x) = NaN. */
        /* If x = NaN or Inf, then tan(x) = NaN. */

-       if (z.bits.exp == 32767)
+       if (z.bits.exp == 0x7fff)

                return (x - x) / (x - x);
 
                return (x - x) / (x - x);
 

-       /* Optimize the case where x is already within range. */
+       /* |x| < (double)pi/4 */

        if (z.e < M_PI_4) {
        if (z.e < M_PI_4) {

-               hi = __tanl(z.e, 0, 0);
-               return s ? -hi : hi;
+               /* x = +-0 or x is subnormal */
+               if (z.bits.exp == 0)
+                       /* inexact and underflow if x!=0 */
+                       return x + x*0x1p-120f;
+               /* can raise spurious underflow */
+               return __tanl(x, 0, 0);

        }
 
        }
 

-       e0 = __rem_pio2l(x, y);
-       hi = y[0];
-       lo = y[1];
-
-       switch (e0 & 3) {
-       case 0:
-       case 2:
-               hi = __tanl(hi, lo, 0);
-               break;
-       case 1:
-       case 3:
-               hi = __tanl(hi, lo, 1);
-               break;
-       }
-       return hi;
+       n = __rem_pio2l(x, y);
+       return __tanl(y[0], y[1], n&1);

 }
 #endif
 }
 #endif