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authorUlrich Drepper <drepper@redhat.com>2009-08-25 22:44:34 -0700
committerUlrich Drepper <drepper@redhat.com>2009-08-25 22:44:34 -0700
commite6fd9b2490295b3c6901e06b94ea077ac1f9fc79 (patch)
tree02575330e17d8bf8c8dfc7154c5eba83fa7be8c7 /sysdeps/ieee754
parent84057895201ee244894e8847c933df6db5aa25a3 (diff)
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Optimized rint implementation for x86-64.
Diffstat (limited to 'sysdeps/ieee754')
-rw-r--r--sysdeps/ieee754/dbl-64/wordsize-64/s_rint.c79
1 files changed, 79 insertions, 0 deletions
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
index 0000000000..4a60aa3278
--- /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