Curtis L. Olson wrote:
> I believe that plib has some endiannes tests. Also simgear, have a
> look at simgear/io/lowlevel.hxx (towards the end)
Right. But those are runtime tests. What Nasal needs to modify is a
structure order, which can only be done at compile time. Simplified,
the naRef structure looks like this:
typedef union {
double num;
struct {
void* ptr;
int magic;
} ref;
} naRef;
On a little endian system, the "magic" ends up in the top 32 bits of
the double. So it can make the double look like a NaN by setting the
appropriate exponent bits. And on a 64 bit system, the double and
pointer are the same size, so the magic lives all by itself. But on a
big endian 32 bit architecture, we need to modify the inner "ref"
struct to have the magic number first.
Andy
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