64-bit optimized implementation of trunc.

1 files changed, 56 insertions, 0 deletions

diff --git a/sysdeps/ieee754/dbl-64/wordsize-64/s_trunc.c b/sysdeps/ieee754/dbl-64/wordsize-64/s_trunc.c
new file mode 100644
index 0000000000..9add5ade71
--- /dev/null
+++ b/sysdeps/ieee754/dbl-64/wordsize-64/s_trunc.c
@@ -0,0 +1,56 @@
+/* Truncate argument to nearest integral value not larger than the argument.
+   Copyright (C) 1997, 1998, 2009 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <math.h>
+
+#include "math_private.h"
+
+
+double
+__trunc (double x)
+{
+  int64_t i0, j0;
+  int64_t sx;
+
+  EXTRACT_WORDS64 (i0, x);
+  sx = i0 & UINT64_C(0x8000000000000000);
+  j0 = ((i0 >> 52) & 0x7ff) - 0x3ff;
+  if (j0 < 52)
+    {
+      if (j0 < 0)
+	/* The magnitude of the number is < 1 so the result is +-0.  */
+	INSERT_WORDS64 (x, sx);
+      else
+	INSERT_WORDS64 (x, sx | (i0 & ~(UINT64_C(0x000fffffffffffff) >> j0)));
+    }
+  else
+    {
+      if (j0 == 0x400)
+	/* x is inf or NaN.  */
+	return x + x;
+    }
+
+  return x;
+}
+weak_alias (__trunc, trunc)
+#ifdef NO_LONG_DOUBLE
+strong_alias (__trunc, __truncl)
+weak_alias (__trunc, truncl)
+#endif