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

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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
This commit is contained in:
ThorstenB
2011-06-02 10:05:10 +02:00
parent f8a337fb9f
commit 3d109f9c4c
1 changed files with 3 additions and 2 deletions
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5
simgear/nasal/data.h
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@@ -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)