remove LFS64 symbol aliases; replace with dynamic linker remapping

[musl] / src / math / __rem_pio2.c

diff --git a/src/math/__rem_pio2.c b/src/math/__rem_pio2.c
index a40db9f..dcf672f 100644 (file)
--- a/src/math/__rem_pio2.c
+++ b/src/math/__rem_pio2.c
@@ -36,6 +36,7 @@
  */
 static const double
 toint   = 1.5/EPS,
+pio4    = 0x1.921fb54442d18p-1,
 invpio2 = 6.36619772367581382433e-01, /* 0x3FE45F30, 0x6DC9C883 */
 pio2_1  = 1.57079632673412561417e+00, /* 0x3FF921FB, 0x54400000 */
 pio2_1t = 6.07710050650619224932e-11, /* 0x3DD0B461, 0x1A626331 */
@@ -117,11 +118,23 @@ int __rem_pio2(double x, double *y)
        }
        if (ix < 0x413921fb) {  /* |x| ~< 2^20*(pi/2), medium size */
 medium:
-               /* rint(x/(pi/2)), Assume round-to-nearest. */
-               fn = x*invpio2 + toint - toint;
+               /* rint(x/(pi/2)) */
+               fn = (double_t)x*invpio2 + toint - toint;
                n = (int32_t)fn;
                r = x - fn*pio2_1;
                w = fn*pio2_1t;  /* 1st round, good to 85 bits */
+               /* Matters with directed rounding. */
+               if (predict_false(r - w < -pio4)) {
+                       n--;
+                       fn--;
+                       r = x - fn*pio2_1;
+                       w = fn*pio2_1t;
+               } else if (predict_false(r - w > pio4)) {
+                       n++;
+                       fn++;
+                       r = x - fn*pio2_1;
+                       w = fn*pio2_1t;
+               }
                y[0] = r - w;
                u.f = y[0];
                ey = u.i>>52 & 0x7ff;