elf.h: add ELFCOMPRESS_ZSTD

[musl] / src / math / lgamma_r.c

diff --git a/src/math/lgamma_r.c b/src/math/lgamma_r.c
index e3ed173..f9984cd 100644 (file)
--- a/src/math/lgamma_r.c
+++ b/src/math/lgamma_r.c
@@ -81,7 +81,6 @@
 #include "libm.h"
 
 static const double
-two52= 4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
 pi  =  3.14159265358979311600e+00, /* 0x400921FB, 0x54442D18 */
 a0  =  7.72156649015328655494e-02, /* 0x3FB3C467, 0xE37DB0C8 */
 a1  =  3.22467033424113591611e-01, /* 0x3FD4A34C, 0xC4A60FAD */
@@ -146,91 +145,62 @@ w4  = -5.95187557450339963135e-04, /* 0xBF4380CB, 0x8C0FE741 */
 w5  =  8.36339918996282139126e-04, /* 0x3F4B67BA, 0x4CDAD5D1 */
 w6  = -1.63092934096575273989e-03; /* 0xBF5AB89D, 0x0B9E43E4 */
 
+/* sin(pi*x) assuming x > 2^-100, if sin(pi*x)==0 the sign is arbitrary */
 static double sin_pi(double x)
 {
-       double y,z;
-       int n,ix;
+       int n;
 
-       GET_HIGH_WORD(ix, x);
-       ix &= 0x7fffffff;
+       /* spurious inexact if odd int */
+       x = 2.0*(x*0.5 - floor(x*0.5));  /* x mod 2.0 */
 
-       if (ix < 0x3fd00000)
-               return __sin(pi*x, 0.0, 0);
+       n = (int)(x*4.0);
+       n = (n+1)/2;
+       x -= n*0.5f;
+       x *= pi;
 
-       y = -x;  /* negative x is assumed */
-
-       /*
-        * argument reduction, make sure inexact flag not raised if input
-        * is an integer
-        */
-       z = floor(y);
-       if (z != y) {    /* inexact anyway */
-               y *= 0.5;
-               y  = 2.0*(y - floor(y));   /* y = |x| mod 2.0 */
-               n  = (int)(y*4.0);
-       } else {
-               if (ix >= 0x43400000) {
-                       y = 0.0;    /* y must be even */
-                       n = 0;
-               } else {
-                       if (ix < 0x43300000)
-                               z = y + two52;  /* exact */
-                       GET_LOW_WORD(n, z);
-                       n &= 1;
-                       y = n;
-                       n <<= 2;
-               }
-       }
        switch (n) {
-       case 0:  y =  __sin(pi*y, 0.0, 0); break;
-       case 1:
-       case 2:  y =  __cos(pi*(0.5-y), 0.0); break;
-       case 3:
-       case 4:  y =  __sin(pi*(1.0-y), 0.0, 0); break;
-       case 5:
-       case 6:  y = -__cos(pi*(y-1.5), 0.0); break;
-       default: y =  __sin(pi*(y-2.0), 0.0, 0); break;
+       default: /* case 4: */
+       case 0: return __sin(x, 0.0, 0);
+       case 1: return __cos(x, 0.0);
+       case 2: return __sin(-x, 0.0, 0);
+       case 3: return -__cos(x, 0.0);
        }
-       return -y;
 }
 
-
 double __lgamma_r(double x, int *signgamp)
 {
-       double t,y,z,nadj,p,p1,p2,p3,q,r,w;
-       int32_t hx;
-       int i,lx,ix;
-
-       EXTRACT_WORDS(hx, lx, x);
+       union {double f; uint64_t i;} u = {x};
+       double_t t,y,z,nadj,p,p1,p2,p3,q,r,w;
+       uint32_t ix;
+       int sign,i;
 
        /* purge off +-inf, NaN, +-0, tiny and negative arguments */
        *signgamp = 1;
-       ix = hx & 0x7fffffff;
+       sign = u.i>>63;
+       ix = u.i>>32 & 0x7fffffff;
        if (ix >= 0x7ff00000)
                return x*x;
-       if ((ix|lx) == 0)
-               return 1.0/0.0;
-       if (ix < 0x3b900000) {  /* |x|<2**-70, return -log(|x|) */
-               if(hx < 0) {
+       if (ix < (0x3ff-70)<<20) {  /* |x|<2**-70, return -log(|x|) */
+               if(sign) {
+                       x = -x;
                        *signgamp = -1;
-                       return -log(-x);
                }
                return -log(x);
        }
-       if (hx < 0) {
-               if (ix >= 0x43300000)  /* |x|>=2**52, must be -integer */
-                       return 1.0/0.0;
+       if (sign) {
+               x = -x;
                t = sin_pi(x);
                if (t == 0.0) /* -integer */
-                       return 1.0/0.0;
-               nadj = log(pi/fabs(t*x));
-               if (t < 0.0)
+                       return 1.0/(x-x);
+               if (t > 0.0)
                        *signgamp = -1;
-               x = -x;
+               else
+                       t = -t;
+               nadj = log(pi/(t*x));
        }
 
        /* purge off 1 and 2 */
-       if (((ix - 0x3ff00000)|lx) == 0 || ((ix - 0x40000000)|lx) == 0)
+       if ((ix == 0x3ff00000 || ix == 0x40000000) && (uint32_t)u.i == 0)
                r = 0;
        /* for x < 2.0 */
        else if (ix < 0x40000000) {
@@ -305,7 +275,7 @@ double __lgamma_r(double x, int *signgamp)
                r = (x-0.5)*(t-1.0)+w;
        } else                         /* 2**58 <= x <= inf */
                r =  x*(log(x)-1.0);
-       if (hx < 0)
+       if (sign)
                r = nadj - r;
        return r;
 }