fix #314: Nasal not working on i386/32bit systems with gcc>=4.5.x

Change magic Nasal reftag to encode a quiet NaN (qNaN) instead of a
signaling NaN (sNaN), since sNaNs cannot pass cleanly through an FPU
(an sNaN is always converted to a qNaN, even by simple FPU load/store
instructions). gcc 4.5.x uses float load/store operations more
aggressively to move our 64bit Nasal variables (naRef) around.

Signed-off-by: Andy Ross

diff --git a/simgear/nasal/data.h b/simgear/nasal/data.h
index 8f1715a332a9ce020103ba48aaf483fabcb67d55..deb4fbdc194abd2618edb510d3cbbb8b0aef750c 100644 (file)
--- a/simgear/nasal/data.h
+++ b/simgear/nasal/data.h
@@ -49,10 +49,11 @@
 
 // On 32 bit systems where the pointer is half the width of the
 // double, we store a special magic number in the structure to make
-// the double a NaN.  This must appear in the top bits of the double,
+// the double a qNaN.  This must appear in the top bits of the double,
 // which is why the structure layout is endianness-dependent.
+// qNaN (quiet NaNs) use range 0x7ff80000-0x7fffffff
 
-#define NASAL_REFTAG 0x7ff56789 // == 2,146,789,257 decimal
+#define NASAL_REFTAG 0x7fff6789 // == 2,147,444,617 decimal
 #define IS_REF(r) ((r).ref.reftag == NASAL_REFTAG)
 #define PTR(r) ((r).ref.ptr)