[x264-devel] Fwd: rbit and HAVE_ARMV6T2

[Andrei Gherzan]

Hello,

I encountered an issue while compiling x264 for armv6 based
RaspberryPi boards . The thumb instruction rbit is not available for
all armv6 but only from armv6t2 which is not the case for the
RapsberryPi boards based on armv6. These boards come with armv6z.

x264 configure script checks, using HAVE_ARMV6T2, if armv6t2 specific
instructions are available but then, when compiling, quant-a.S is
picked and compiled with rbit instruction unconditionally.

One way to fix it would be to use --disable-asm but this disables all
the optimisations even though this is the only instruction failing (if
I remove this specific instruction the build completes successfully).

The better way to do it would be, in my opinion , to emulate this
instruction when unavailable. What do you guys think?

Thanks,

--
Andrei Gherzan