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***spacy51*** · 10-29-2008 08:12 PM

I noticed that when reading or writing to a save state, the core uses sizeof() to determine the number of bytes to read.

This will make save states incompatible when compiled on a system where integers are not 4 bytes.

Code:

int utilReadInt(gzFile gzFile)

{

  int i = 0;

  utilGzRead(gzFile, &i, sizeof(int));

  return i;

}

***Squall Leonhart*** · 10-29-2008 09:48 PM

hasn't been a problem so far.

**bgK** · 10-29-2008 09:56 PM

This indeed is a problem if you want to exchange save states between 32 bits and 64 bits machines.

***Squall Leonhart*** · 10-30-2008 01:31 AM

oh?

well as long as the fix is able to read the current format, so as to load and save them to the new.

**SCHUMI4EVER** · 10-30-2008 11:28 PM

(10-29-2008 09:56 PM)bgK Wrote: This indeed is a problem if you want to exchange save states between 32 bits and 64 bits machines.

Wait, so all my saves made in XP will stop working when I switch to Vista Home Premium 64bit?

**bgK** · 10-30-2008 11:30 PM

If you use a 64bits build of VBA-M and the bug is not fixed, yes.

**SCHUMI4EVER** · 10-30-2008 11:40 PM

If I continue to use a 32bit build then everything will be fine though?

There has not been a 64bit build in a while so I was planning on using the 32bit build anyways.

***spacy51*** · 10-31-2008 03:42 AM

As I said, it's only a problem when int is not 4 bytes. IIRC, on Windows 64 integers are still 4 bytes, only pointers are 8 bytes long automatically.

Tantric · 10-31-2008 04:29 AM

Actually you do make a good point (I think). This is something to avoid. This can be a problem for big endian vs little endian architecture. I actually don't use any of this code to avoid running into such problems =)
Here's a post I happened across just yesterday:
http://www.tehskeen.com/forums/showthread.php?p=43389

See shagkur's response.

**bgK** · 10-31-2008 06:47 PM

(10-31-2008 03:42 AM)spacy51 Wrote: As I said, it's only a problem when int is not 4 bytes. IIRC, on Windows 64 integers are still 4 bytes, only pointers are 8 bytes long automatically.

My mistake, then. However I know for sure it'll be a problem on Linux and MacOS 64bits where sizeof(int) is 8.

***Squall Leonhart*** · 11-01-2008 12:35 AM

so the int should be dynamic, rather then static?

***spacy51*** · 11-01-2008 07:44 AM

(11-01-2008 12:35 AM)Squall Leonhart Wrote: so the int should be dynamic, rather then static?

No, the other way round. Instead of sizeof(int), which may vary depending on the compiler/platform, we should use a static number of bytes per value, and declare the file as little-endian.

***Squall Leonhart*** · 11-04-2008 10:58 AM

oh, that makes complete sense now.

lanceaugust31 · 09-01-2009 02:34 AM

When reading or writing to a save state, the core uses sizeof() to determine the number of bytes to read. what should we do if in that case? Badger

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