[svn-r12425] Purpose: Bug fix

Description: Data conversion from long double to (unsigned) long long
returns some incorrect values on Mac OS 10.4 and SGI IRIX64 6.5.  The
conversions start to go wrong when the long double is
20041683600089727.779961 (0x4351ccf385ebc8a0bfcc2a...).  If adjusting
the values higher by assigning 0x...c8a0cf... or 0x...c8a0df..., the
converted values go wild.

Solution: Detect this error in configure.in and disable compiler
conversions from long double to (unsigned) long long for Mac OS 10.4
and IRIX64 6.5.

Platforms tested: h5committest, Mac OS 10.4, and IRIX64 6.5.

1 files changed, 100 insertions, 0 deletions

diff --git a/configure b/configure
index ec9fb85..78468ad 100755
--- a/configure
+++ b/configure
@@ -51683,6 +51683,106 @@ else
 echo "${ECHO_T}no" >&6
 fi
 
+echo "$as_me:$LINENO: checking if correctly converting long double to (unsigned) long long values" >&5
+echo $ECHO_N "checking if correctly converting long double to (unsigned) long long values... $ECHO_C" >&6
+
+if test ${ac_cv_sizeof_long_double} = 0; then
+   hdf5_ldouble_to_llong_accurate=${hdf5_ldouble_to_llong_accurate=no}
+else
+   if test "${hdf5_ldouble_to_llong_accurate+set}" = set; then
+  echo $ECHO_N "(cached) $ECHO_C" >&6
+else
+  if test "$cross_compiling" = yes; then
+  { { echo "$as_me:$LINENO: error: cannot run test program while cross compiling
+See \`config.log' for more details." >&5
+echo "$as_me: error: cannot run test program while cross compiling
+See \`config.log' for more details." >&2;}
+   { (exit 1); exit 1; }; }
+else
+  cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+        int main(void)
+        {
+            long double         ld = 20041683600089727.779961L;
+            long long           ll;
+            unsigned long long  ull;
+            unsigned char       s[16];
+            int                 ret = 0;
+
+            if(sizeof(long double) == 16) {
+                /*make sure the long double type is the same as the failing type
+                 *which has 16 bytes in size and 11 bits of exponent.  If it is,
+                 *the bit sequence should be like below.  It's not
+                 *a decent way to check but this info isn't available. */
+                memcpy(s, &ld, 16);
+                if(s[0]==0x43 && s[1]==0x51 && s[2]==0xcc && s[3]==0xf3 &&
+                    s[4]==0x85 && s[5]==0xeb && s[6]==0xc8 && s[7]==0xa0 &&
+                    s[8]==0xbf && s[9]==0xcc && s[10]==0x2a && s[11]==0x3c) {
+
+                    /*slightly adjust the bit sequence (s[8]=0xdf).  The converted
+                     *values will go wild on Mac OS 10.4 and IRIX64 6.5.*/
+                    s[0]=0x43; s[1]=0x51; s[2]=0xcc; s[3]=0xf3;
+                    s[4]=0x85; s[5]=0xeb; s[6]=0xc8; s[7]=0xa0;
+                    s[8]=0xdf; s[9]=0xcc; s[10]=0x2a; s[11]=0x3c;
+                    s[12]=0x3d; s[13]=0x85; s[14]=0x56; s[15]=0x20;
+
+                    memcpy(&ld, s, 16);
+                    ll = (long long)ld;
+                    ull = (unsigned long long)ld;
+
+                    if(ll != 20041683600089728 || ull != 20041683600089728)
+                        ret = 1;
+                }
+            }
+    done:
+            exit(ret);
+        }
+
+_ACEOF
+rm -f conftest$ac_exeext
+if { (eval echo "$as_me:$LINENO: \"$ac_link\"") >&5
+  (eval $ac_link) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && { ac_try='./conftest$ac_exeext'
+  { (eval echo "$as_me:$LINENO: \"$ac_try\"") >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  hdf5_ldouble_to_llong_accurate=yes
+else
+  echo "$as_me: program exited with status $ac_status" >&5
+echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+( exit $ac_status )
+hdf5_ldouble_to_llong_accurate=no
+fi
+rm -f core *.core gmon.out bb.out conftest$ac_exeext conftest.$ac_objext conftest.$ac_ext
+fi
+fi
+
+fi
+
+if test ${hdf5_ldouble_to_llong_accurate} = "yes"; then
+
+cat >>confdefs.h <<\_ACEOF
+#define LDOUBLE_TO_LLONG_ACCURATE 1
+_ACEOF
+
+  echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6
+else
+  echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6
+fi
+
 
 H5_VERSION="`cut -d' ' -f3 $srcdir/README.txt | head -1`"