[PATCH] Fix FileSetReader/Writer

[Richard Guenther]

On Wed, 1 Sep 2004, Richard Guenther wrote:

> On Wed, 1 Sep 2004 address@hidden wrote:
>
> >   regressions.io.filesetreadertest1             : FAIL
> >     Unexpected exit_code, standard error.
> >
> >   regressions.io.filesetreadertest2             : FAIL
> >     Unexpected exit_code, standard error.
>
> I finally figured out why these fail on ia32 (but not on amd64 and ia64).
> The test data was appearantly generated on a 64bit big-endian host and the
> reader just reads bytes and expects a C++ long to be 64bit everywhere
> (which is not true obviously).
>
> There is also the POOMA_HAS_LONG_LONG define which is set nowhere
> and used only in the FileSetReader/Writer and ElementProperties.
>
> We could check for an appropriate 64bit type during configure and
> use that or just ignore the issue.

Yay, and of course this is not enough, as required alignment for 64bit
datatypes is of course different.  We should shoot the one that came up
with

  template <class T>
  struct OffsetData
  {
    void reverseBytes();

    int nodedata[6*Dim];  // domain data (same format as .layout)
    bool isCompressed;    // Is the data compressed
    Offset_t offset;      // offset in sizeof(T) units
    T compressedValue;    // Data value, if compressed
  };

as possibly "portable" structure to write byte-for-byte to a file.
Placing bool between int and long long is surely not a good idea.

Changing the above to

    int nodedata[6*Dim];  // domain data (same format as .layout)
    union {
      bool isCompressed;  // Is the data compressed
      char pad[8];
    } u;
    Offset_t offset;      // offset in sizeof(T) units

_seems_ to "fix" the problem.

So, is the following patch ok?  Tested on ia32, amd64 and ia64 linux.


2004Sep01  Richard Guenther <address@hidden>

        * configure: add POOMA_HAS_LONG_LONG and POOMA_INT64
        defines.
        scripts/configure.ac: check for long long and sizes of
        long and long long.  Set POOMA_HAS_LONG_LONG and
        POOMA_INT64 appropriately.
        scripts/configure: regenerate.
        src/IO/FileSetReader.h: use POOMA_INT64 for Offset_t,
        pad bool inside OffsetData to 64bit using a union.
        src/IO/FileSetWriter.h: likewise.
        src/IO/FileSetReader.cpp: honour union.

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