isnan: port to VAX

[gnulib.git] / lib / isnan.c

diff --git a/lib/isnan.c b/lib/isnan.c
index ddad7fb..10596a9 100644 (file)
--- a/lib/isnan.c
+++ b/lib/isnan.c
@@ -1,5 +1,5 @@
 /* Test for NaN that does not need libm.
-   Copyright (C) 2007-2010 Free Software Foundation, Inc.
+   Copyright (C) 2007-2013 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
@@ -21,7 +21,7 @@
 /* Specification.  */
 #ifdef USE_LONG_DOUBLE
 /* Specification found in math.h or isnanl-nolibm.h.  */
-extern int rpl_isnanl (long double x);
+extern int rpl_isnanl (long double x) _GL_ATTRIBUTE_CONST;
 #elif ! defined USE_FLOAT
 /* Specification found in math.h or isnand-nolibm.h.  */
 extern int rpl_isnand (double x);
@@ -79,11 +79,22 @@ extern int rpl_isnanf (float x);
   ((sizeof (DOUBLE) + sizeof (unsigned int) - 1) / sizeof (unsigned int))
 typedef union { DOUBLE value; unsigned int word[NWORDS]; } memory_double;
 
+/* Most hosts nowadays use IEEE floating point, so they use IEC 60559
+   representations, have infinities and NaNs, and do not trap on
+   exceptions.  Define IEEE_FLOATING_POINT if this host is one of the
+   typical ones.  The C11 macro __STDC_IEC_559__ is close to what is
+   wanted here, but is not quite right because this file does not require
+   all the features of C11 Annex F (and does not require C11 at all,
+   for that matter).  */
+
+#define IEEE_FLOATING_POINT (FLT_RADIX == 2 && FLT_MANT_DIG == 24 \
+                             && FLT_MIN_EXP == -125 && FLT_MAX_EXP == 128)
+
 int
 FUNC (DOUBLE x)
 {
-#ifdef KNOWN_EXPBIT0_LOCATION
-# if defined USE_LONG_DOUBLE && ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_))
+#if defined KNOWN_EXPBIT0_LOCATION && IEEE_FLOATING_POINT
+# if defined USE_LONG_DOUBLE && ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
   /* Special CPU dependent code is needed to treat bit patterns outside the
      IEEE 754 specification (such as Pseudo-NaNs, Pseudo-Infinities,
      Pseudo-Zeroes, Unnormalized Numbers, and Pseudo-Denormals) as NaNs.
@@ -117,17 +128,20 @@ FUNC (DOUBLE x)
 # else
   /* Be careful to not do any floating-point operation on x, such as x == x,
      because x may be a signaling NaN.  */
-#  if defined __TINYC__ || defined __SUNPRO_C || defined __DECC \
+#  if defined __SUNPRO_C || defined __ICC || defined _MSC_VER \
+      || defined __DECC || defined __TINYC__ \
       || (defined __sgi && !defined __GNUC__)
-  /* The Sun C 5.0 compilers and the Compaq (ex-DEC) 6.4 compilers don't
-     recognize the initializers as constant expressions.  The latter compiler
-     also fails when constant-folding 0.0 / 0.0 even when constant-folding is
-     not required.  The SGI MIPSpro C compiler complains about "floating-point
-     operation result is out of range".  */
+  /* The Sun C 5.0, Intel ICC 10.0, Microsoft Visual C/C++ 9.0, Compaq (ex-DEC)
+     6.4, and TinyCC compilers don't recognize the initializers as constant
+     expressions.  The Compaq compiler also fails when constant-folding
+     0.0 / 0.0 even when constant-folding is not required.  The Microsoft
+     Visual C/C++ compiler also fails when constant-folding 1.0 / 0.0 even
+     when constant-folding is not required. The SGI MIPSpro C compiler
+     complains about "floating-point operation result is out of range".  */
   static DOUBLE zero = L_(0.0);
   memory_double nan;
-  DOUBLE plus_inf = L_(1.0) / L_(0.0);
-  DOUBLE minus_inf = -L_(1.0) / L_(0.0);
+  DOUBLE plus_inf = L_(1.0) / zero;
+  DOUBLE minus_inf = -L_(1.0) / zero;
   nan.value = zero / zero;
 #  else
   static memory_double nan = { L_(0.0) / L_(0.0) };
@@ -150,11 +164,12 @@ FUNC (DOUBLE x)
   }
 # endif
 #else
-  /* The configuration did not find sufficient information.  Give up about
-     the signaling NaNs, handle only the quiet NaNs.  */
+  /* The configuration did not find sufficient information, or does
+     not use IEEE floating point.  Give up about the signaling NaNs;
+     handle only the quiet NaNs.  */
   if (x == x)
     {
-# if defined USE_LONG_DOUBLE && ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_))
+# if defined USE_LONG_DOUBLE && ((defined __ia64 && LDBL_MANT_DIG == 64) || (defined __x86_64__ || defined __amd64__) || (defined __i386 || defined __i386__ || defined _I386 || defined _M_IX86 || defined _X86_)) && !HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
       /* Detect any special bit patterns that pass ==; see comment above.  */
       memory_double m1;
       memory_double m2;