X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fceil.c;h=fbcca33a4a4dfcbdae30e57ae4d759c0552d278d;hb=fa1db0dd22768f09a507674a30beb5b8a87bb35f;hp=2538bf64d412720275960a58995f09d5b3bdc0fb;hpb=57fdfd3f8ec62b105c53bcdf6f127c35c7fe7391;p=gnulib.git

diff --git a/lib/ceil.c b/lib/ceil.c
index 2538bf64d..fbcca33a4 100644
--- a/lib/ceil.c
+++ b/lib/ceil.c
@@ -1,5 +1,5 @@
 /* Round towards positive infinity.
-   Copyright (C) 2007 Free Software Foundation, Inc.
+   Copyright (C) 2007, 2010-2013 Free Software Foundation, Inc.
 
    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -16,32 +16,52 @@
 
 /* Written by Bruno Haible <bruno@clisp.org>, 2007.  */
 
-#include <config.h>
+#if ! defined USE_LONG_DOUBLE
+# include <config.h>
+#endif
 
 /* Specification.  */
 #include <math.h>
 
 #include <float.h>
 
+#undef MIN
+
 #ifdef USE_LONG_DOUBLE
 # define FUNC ceill
 # define DOUBLE long double
 # define MANT_DIG LDBL_MANT_DIG
+# define MIN LDBL_MIN
 # define L_(literal) literal##L
 #elif ! defined USE_FLOAT
 # define FUNC ceil
 # define DOUBLE double
 # define MANT_DIG DBL_MANT_DIG
+# define MIN DBL_MIN
 # define L_(literal) literal
 #else /* defined USE_FLOAT */
 # define FUNC ceilf
 # define DOUBLE float
 # define MANT_DIG FLT_MANT_DIG
+# define MIN FLT_MIN
 # define L_(literal) literal##f
 #endif
 
+/* -0.0.  See minus-zero.h.  */
+#if defined __hpux || defined __sgi || defined __ICC
+# define MINUS_ZERO (-MIN * MIN)
+#else
+# define MINUS_ZERO L_(-0.0)
+#endif
+
+/* MSVC with option -fp:strict refuses to compile constant initializers that
+   contain floating-point operations.  Pacify this compiler.  */
+#ifdef _MSC_VER
+# pragma fenv_access (off)
+#endif
+
 /* 2^(MANT_DIG-1).  */
-static const double TWO_MANT_DIG =
+static const DOUBLE TWO_MANT_DIG =
   /* Assume MANT_DIG <= 5 * 31.
      Use the identity
        n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5).  */
@@ -63,20 +83,35 @@ FUNC (DOUBLE x)
   volatile DOUBLE y = x;
   volatile DOUBLE z = y;
 
-  /* Round to the next integer (nearest or up or down, doesn't matter).  */
   if (z > L_(0.0))
     {
-      z += TWO_MANT_DIG;
-      z -= TWO_MANT_DIG;
+      /* Avoid rounding errors for values near 2^k, where k >= MANT_DIG-1.  */
+      if (z < TWO_MANT_DIG)
+        {
+          /* Round to the next integer (nearest or up or down, doesn't matter).  */
+          z += TWO_MANT_DIG;
+          z -= TWO_MANT_DIG;
+          /* Enforce rounding up.  */
+          if (z < y)
+            z += L_(1.0);
+        }
     }
   else if (z < L_(0.0))
     {
-      z -= TWO_MANT_DIG;
-      z += TWO_MANT_DIG;
+      /* For -1 < x < 0, return -0.0 regardless of the current rounding
+         mode.  */
+      if (z > L_(-1.0))
+        z = MINUS_ZERO;
+      /* Avoid rounding errors for values near -2^k, where k >= MANT_DIG-1.  */
+      else if (z > - TWO_MANT_DIG)
+        {
+          /* Round to the next integer (nearest or up or down, doesn't matter).  */
+          z -= TWO_MANT_DIG;
+          z += TWO_MANT_DIG;
+          /* Enforce rounding up.  */
+          if (z < y)
+            z += L_(1.0);
+        }
     }
-  /* Enforce rounding up.  */
-  if (z < y)
-    z += L_(1.0);
-
   return z;
 }