[FFmpeg-devel] forcing ints to be 64 bits, possible new FATE client idea

Ganesh Ajjanagadde gajjanag at mit.edu
Wed Oct 21 04:08:59 CEST 2015

Hi all,

It is known that there exist at least certain parts of the codebase
that do not work correctly if ints are 64 bits. One of them I noticed
was in avutil/intmath.h: ff_ctz_c does not compute the right thing if
int is 64 bits. This is true both before and after the De-Bruijn

A more interesting (and serious) question is whether FATE is broken if
int's are 64 bits. I did some digging, and found the following from
"The Definitive Guide to GCC" - On GCC prior to 4.x, there was a flag
-mint64, documented as follows (see e.g
"Force int and long types to be 64 bits wide. See -mlong32 for an
explanation of the default and the way that the pointer size is

This should be helpful in setting up a FATE client to test (and
possibly fix) bad code that assumed int = 32 bits. I myself can't
easily run such an outdated GCC, but I noticed a bunch of clients
running GCC < 4.0 where this may be set up.


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