[opus] Cross-compiling Opus for Android arm64

[Kostya Vasilyev]

PS - I was able to compile the .S file converted to GNU syntax using

arm-linux-gnueabi-as

So I guess it's for arm v7 only?

But the celt_pitch_xcorr_neon symbol is undefined also when building for
arm64 v8a  (with fixed point math), how to resolve?

-- K

On Thu, May 25, 2023 at 7:22 PM Kostya Vasilyev <kvasilye at justin.tv> wrote:

> Hello,
>
> I'm trying to compile Opus for Android arm64 (and ultimately other arch's)
> using the CMakeLists.txt file available in the repository.
>
> My cmake commands are like this:
>
> https://gist.github.com/kvasilye/9004332a5f3f90f2a6e868090d004d7b
>
> This produces an error:
>
> ld: error: undefined symbol: celt_pitch_xcorr_neon
> >>> referenced by pitch.c:347 (/home/
> ANT.AMAZON.COM/kvasilye/opus/celt/pitch.c:347)
> >>>               CMakeFiles/opus.dir/celt/pitch.c.o:(pitch_search)
> >>> referenced by celt_lpc.c:314 (/home/
> ANT.AMAZON.COM/kvasilye/opus/celt/celt_lpc.c:314)
> >>>               CMakeFiles/opus.dir/celt/celt_lpc.c.o:(_celt_autocorr)
> >>> referenced by burg_modified_FIX.c:98 (/home/
> ANT.AMAZON.COM/kvasilye/opus/silk/fixed/burg_modified_FIX.c:98)
> >>>
> CMakeFiles/opus.dir/silk/fixed/burg_modified_FIX.c.o:(silk_burg_modified_c)
> >>> referenced 2 more times
>
> Next, I tried to write my own CMakeLists.txt and got stuck too - the
> undefined symbol above is defined in celt_pitch_xcorr_arm.s which as I
> understand uses ARM assembler syntax.
>
> I converted the file to GNU syntax using the provided Perl script.
>
> Trying to compile the output with aarch64-linux-gnu-as gives a whole bunch
> of errors like:
>
> third_party/cmake-build-opus-android-arm64-v8a-Debug/celt_pitch_xcorr_arm_gnu.S:
> Assembler messages:
> third_party/cmake-build-opus-android-arm64-v8a-Debug/celt_pitch_xcorr_arm_gnu.S:1:
> Error: unknown pseudo-op: `.syntax'
> third_party/cmake-build-opus-android-arm64-v8a-Debug/celt_pitch_xcorr_arm_gnu.S:2:
> Error: junk at end of line, first unrecognized character is `@'
> third_party/cmake-build-opus-android-arm64-v8a-Debug/celt_pitch_xcorr_arm_gnu.S:3:
> Error: junk at end of line, first unrecognized character is `@'
> third_party/cmake-build-opus-android-arm64-v8a-Debug/celt_pitch_xcorr_arm_gnu.S:4:
> Error: junk at end of line, first unrecognized character is `@'
> third_party/cmake-build-opus-android-arm64-v8a-Debug/celt_pitch_xcorr_arm_gnu.S:5:
> Error: junk at end of line, first unrecognized character is `@'
>
> So it looks unhappy with the syntax.
>
> Questions:
>
> 1 - What is the right way to compile Opus for Android on arm64-v8a?
>
> 2 - If I wanted to compile the asm file, how can I do that?
>
> 3 - Is this asm file for both armeabi-v7a and arm64-v8a or just
> for armeabi-v7a? The symbol is required for arm64-v8a, but there is a
> directive ".arch armv7-a" at the top of the file so I'm confused.
>
> I really don't know anything about arm assembly to figure these out on my
> own, any help would be appreciated!
>
> Thanks,
> -- K
>
>
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