Optimized rint implementation for x86-64.

diff --git a/ChangeLog b/ChangeLog
index 910e188..af3d057 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,7 @@
 2009-08-25  Ulrich Drepper  <drepper@redhat.com>
 
+       * sysdeps/ieee754/dbl-64/wordsize-64/s_rint.c: New file.
+
        * sysdeps/ieee754/dbl-64/wordsize-64/s_round.c: New file.
 
 2009-08-25  Joseph Myers  <joseph@codesourcery.com>

diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_rint.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_rint.c
new file mode 100644 (file)
index 0000000..4a60aa3
--- /dev/null
+++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_rint.c
@@ -0,0 +1,79 @@
+/* @(#)s_rint.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/*
+ * rint(x)
+ * Return x rounded to integral value according to the prevailing
+ * rounding mode.
+ * Method:
+ *     Using floating addition.
+ * Exception:
+ *     Inexact flag raised if x not equal to rint(x).
+ */
+
+#include "math.h"
+#include "math_private.h"
+
+#ifdef __STDC__
+static const double
+#else
+static double
+#endif
+TWO52[2]={
+  4.50359962737049600000e+15, /* 0x43300000, 0x00000000 */
+ -4.50359962737049600000e+15, /* 0xC3300000, 0x00000000 */
+};
+
+#ifdef __STDC__
+       double __rint(double x)
+#else
+       double __rint(x)
+       double x;
+#endif
+{
+       int64_t i0,sx;
+       int32_t j0;
+       EXTRACT_WORDS64(i0,x);
+       sx = (i0>>63)&1;
+       j0 = ((i0>>52)&0x7ff)-0x3ff;
+       if(j0<52) {
+           if(j0<0) {
+               if((i0 & UINT64_C(0x7fffffffffffffff))==0) return x;
+               uint64_t i = i0 & UINT64_C(0xfffffffffffff);
+               i0 &= UINT64_C(0xfffe000000000000);
+               i0 |= (((i|-i) >> 12) & UINT64_C(0x8000000000000));
+               INSERT_WORDS64(x,i0);
+               double w = TWO52[sx]+x;
+               double t =  w-TWO52[sx];
+               EXTRACT_WORDS64(i0,t);
+               INSERT_WORDS64(t,(i0&UINT64_C(0x7fffffffffffffff))|(sx<<63));
+               return t;
+           } else {
+               uint64_t i = UINT64_C(0x000fffffffffffff)>>j0;
+               if((i0&i)==0) return x; /* x is integral */
+               i>>=1;
+               if((i0&i)!=0)
+                   i0 = (i0&(~i))|(UINT64_C(0x4000000000000)>>j0);
+           }
+       } else {
+           if(j0==0x400) return x+x;   /* inf or NaN */
+           else return x;              /* x is integral */
+       }
+       INSERT_WORDS64(x,i0);
+       double w = TWO52[sx]+x;
+       return w-TWO52[sx];
+}
+weak_alias (__rint, rint)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__rint, __rintl)
+weak_alias (__rint, rintl)
+#endif