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Additional comments ono the SQLITE_MIXED_ENDIAN_64BIT_FLOAT issue. (CVS 4029)

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FossilOrigin-Name: dd48a31e671de09f59661b2ba1a20e7b9f09099a
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drh
2007-05-23 07:20:08 +00:00
parent 50027d1c0c
commit 7a4f5023a4
3 changed files with 23 additions and 9 deletions
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18
src/vdbeaux.c
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@@ -1773,10 +1773,24 @@ int sqlite3VdbeSerialTypeLen(u32 serial_type){
/*
** If we are on an architecture with mixed-endian floating
*** points (ex: ARM7) then swap the lower 4 bytes with the
** points (ex: ARM7) then swap the lower 4 bytes with the
** upper 4 bytes. Return the result.
**
** For most (sane) architectures, this is a no-op.
** For most architectures, this is a no-op.
**
** (later): It is reported to me that the mixed-endian problem
** on ARM7 is an issue with GCC, not with the ARM7 chip. It seems
** that early versions of GCC stored the two words of a 64-bit
** float in the wrong order. And that error has been propagated
** ever since. The blame is not necessarily with GCC, though.
** GCC might have just copying the problem from a prior compiler.
** I am also told that newer versions of GCC that follow a different
** ABI get the byte order right.
**
** Developers using SQLite on an ARM7 should compile and run their
** application using -DSQLITE_DEBUG=1 at least once. With DEBUG
** enabled, some asserts below will ensure that the byte order of
** floating point values is correct.
*/
#ifdef SQLITE_MIXED_ENDIAN_64BIT_FLOAT
static double floatSwap(double in){