On 17.09.2010 09:32, Slawomir Testowy wrote:
Hi all!
For some time I have been using tremor with fastermdct patch found on
http://www.rockbox.org/wiki/FasterMDCT. This patch gives huge speedup on
i686/x86_64 machines and smaller, but still significant, speedup on ARM.
Everything works great until I compile tremor on ARM with -fPIC flag (I link
tremor into a shared object). In such case it segfaults in macro TRANSFORM_EQUAL
in file fft-ffmpeg_arm.h at line 158:
asm volatile( "ldmia %[my_z], {%[t5],%[t6]}\n\t":[t5] "=r" (t5), [t6] "=r"
(t6):[my_z] "r" (z));\
When I compile tremor without -fPIC or with -U_ARM_ASSEM_, there is no segfault.
Tremor without fastermdct.patch also doesn't have this problem.
I tried debugging the code for a moment, but this code (MDCT +
#defines + lots of
assmebly) is completely incomprehensible to me.
Unfortunately, I don't have gdb built for this platform (I managed to find the
problematic line with `fprintf(stderr, ...)`, which itself could change the way
it segfaults). At first sight all variables are initialized to proper values.
The ARM processor I'm using is (according to /proc/cpuinfo):
Processor : ARMv6-compatible processor rev 4 (v6l)
CPU implementer : 0x41
CPU architecture: 6TEJ
CPU variant : 0x0
CPU part : 0xb36
CPU revision : 4
Hardware : Freescale MX31/MX32 3-Stack Board
Can you help me handle this issue?
--
regards,
Slawomir Testowy
The android has the same problem (after enabling ASM optimzations),
crash/segfault immediately when trying to play a song. There's a number
of codecs that do not work and most (or all, I don't know exactly) of
them use the mdct: wma, vorbis, aac, a52, cook. I strongly suspect it's
the very same problem, since IIUC the NDKs gcc has -fPIC on by default
(as does the android gcc target in gcc 4.6).
I hope this can be resolved.
Best regards.
