[gdal-dev] GDALDatasetRasterIO - different results between i386 and amd64

[Johan Van de Wauw]

Hello,

While investigating why one of the unit tests of rasterio fails on i386
[1], I think that the actual cause is a different result from gdal when
using GDALDatasetRasterIO.

When opening the test file [2] I get different results when using i386.
I could reproduce this behaviour when using only C code (attached).
i386:
0 8 5 7 0 0 0 0
0 6 61 15 27 15 24 128
0 20 152 23 15 19 28 0
0 18 255 21 129 24 32 0
9 7 14 16 19 18 36 0
6 27 43 207 38 31 73 0
0 0 0 0 74 23 0 0

AMD64 and other architectures:
0 8 5 7 0 0 0 0
0 6 61 15 27 15 24 128
0 20 152 23 15 19 28 0
**0 17 255 25 255 22 32 0 **
9 7 14 16 19 18 36 0
6 27 43 207 38 31 73 0
0 0 0 0 74 23 0 0


Note that the difference only occurs on i386: on other debian
architectures[3,] (including 32 bit like mips, arm) the same result was
found.

Kind Regards,
Johan

[1] https://github.com/mapbox/rasterio/issues/229
[2] https://github.com/mapbox/rasterio/blob/master/tests/data/RGB.byte.tif
[3] https://buildd.debian.org/status/package.php?p=rasterio&suite=unstable
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