math: tan cleanups

[musl] / src / math / __tanl.c

diff --git a/src/math/__tanl.c b/src/math/__tanl.c
index f842543..4b36e61 100644 (file)
--- a/src/math/__tanl.c
+++ b/src/math/__tanl.c
@@ -23,32 +23,12 @@
  * See __cosl.c for more details about the polynomial.
  */
 
-/* Long double constants are slow on these arches, and broken on i386. */
-static const volatile double
-T3hi =  0.33333333333333331,            /*  0x15555555555555.0p-54 */
-T3lo =  1.8350121769317163e-17,         /*  0x15280000000000.0p-108 */
-T5hi =  0.13333333333333336,            /*  0x11111111111112.0p-55 */
-T5lo =  1.3051083651294260e-17,         /*  0x1e180000000000.0p-109 */
-T7hi =  0.053968253968250494,           /*  0x1ba1ba1ba1b827.0p-57 */
-T7lo =  3.1509625637859973e-18,         /*  0x1d100000000000.0p-111 */
-pio4_hi   =  0.78539816339744828,       /*  0x1921fb54442d18.0p-53 */
-pio4_lo   =  3.0628711372715500e-17,    /*  0x11a80000000000.0p-107 */
-pio4lo_hi = -1.2541394031670831e-20,    /* -0x1d9cceba3f91f2.0p-119 */
-pio4lo_lo =  6.1493048227390915e-37;    /*  0x1a280000000000.0p-173 */
-#define T3      ((long double)T3hi + T3lo)
-#define T5      ((long double)T5hi + T5lo)
-#define T7      ((long double)T7hi + T7lo)
-#define pio4    ((long double)pio4_hi + pio4_lo)
-#define pio4lo  ((long double)pio4lo_hi + pio4lo_lo)
-
-#if 0
 static const long double
 T3 =  0.333333333333333333180L,         /*  0xaaaaaaaaaaaaaaa5.0p-65 */
 T5 =  0.133333333333333372290L,         /*  0x88888888888893c3.0p-66 */
 T7 =  0.0539682539682504975744L,        /*  0xdd0dd0dd0dc13ba2.0p-68 */
 pio4   =  0.785398163397448309628L,     /*  0xc90fdaa22168c235.0p-64 */
 pio4lo = -1.25413940316708300586e-20L;  /* -0xece675d1fc8f8cbb.0p-130 */
-#endif
 
 static const double
 T9  =  0.021869488536312216,            /*  0x1664f4882cc1c2.0p-58 */
@@ -65,26 +45,21 @@ T29 =  0.0000078293456938132840,        /*  0x106b59141a6cb3.0p-69 */
 T31 = -0.0000032609076735050182,        /* -0x1b5abef3ba4b59.0p-71 */
 T33 =  0.0000023261313142559411;        /*  0x13835436c0c87f.0p-71 */
 
-long double __tanl(long double x, long double y, int iy) {
+long double __tanl(long double x, long double y, int odd) {
        long double z, r, v, w, s, a, t;
-       long double osign;
-       int i;
+       int big, sign;
 
-       iy = iy == 1 ? -1 : 1;        /* XXX recover original interface */
-       // FIXME: this is wrong, use copysign, signbit or union bithack
-       osign = x >= 0 ? 1.0 : -1.0;  /* XXX slow, probably wrong for -0 */
-       if (fabsl(x) >= 0.67434) {
+       big = fabsl(x) >= 0.67434;
+       if (big) {
+               sign = 0;
                if (x < 0) {
+                       sign = 1;
                        x = -x;
                        y = -y;
                }
-               z = pio4 - x;
-               w = pio4lo - y;
-               x = z + w;
+               x = (pio4 - x) + (pio4lo - y);
                y = 0.0;
-               i = 1;
-       } else
-               i = 0;
+       }
        z = x * x;
        w = z * z;
        r = T5 + w * (T9 + w * (T13 + w * (T17 + w * (T21 +
@@ -92,14 +67,14 @@ long double __tanl(long double x, long double y, int iy) {
        v = z * (T7 + w * (T11 + w * (T15 + w * (T19 + w * (T23 +
             w * (T27 + w * T31))))));
        s = z * x;
-       r = y + z * (s * (r + v) + y);
-       r += T3 * s;
+       r = y + z * (s * (r + v) + y) + T3 * s;
        w = x + r;
-       if (i == 1) {
-               v = (long double)iy;
-               return osign * (v - 2.0 * (x - (w * w / (w + v) - r)));
+       if (big) {
+               s = 1 - 2*odd;
+               v = s - 2.0 * (x + (r - w * w / (w + s)));
+               return sign ? -v : v;
        }
-       if (iy == 1)
+       if (!odd)
                return w;
 
        /*