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4502948cd8
inverse_channel_transform() ran its general N-channel matrix loop for every sample of a stereo stream, where the matrix is exactly +-1.0. That loop was a quarter to a third of the whole decode, and GCC 9.5.0 compiles it worse than 4.9.4 did, which made the codec 6-9% slower on ARM7TDMI after the toolchain update. Handle a group of two channels separately: add and subtract when the matrix is +-1.0, and a plain four multiply loop otherwise. More than two channels still use the general loop. This reverses the regression from the GCC 9.5.0 update and goes well past it. The loop the newer compiler handled badly is no longer used for stereo, so the two compilers now give the same speed to within 1%, about 25% faster than the codec was with GCC 4.9.4 (estimated with perfsim, e200v1, wmapro_141k: 25.81 MHz with 4.9.4 before this change, 19.5 MHz with either compiler after it). Output is bit-identical: whole-file PCM hashes match before and after for five stereo files at 55-271 kbps, built with GCC 9.5.0 and with 4.9.4, and also with the multiply path forced on. Measured with test_codec, wmapro_141k.wma, MHz for real time: Sansa e200v1 27.99 -> 19.70 Sansa Clip+ 21.78 -> 15.80 Estimated with perfsim for the other files (e200v1 / Clip+): wmapro_55k 25.21 -> 17.06 / 20.02 -> 13.71 wmapro_80k 26.17 -> 18.01 / 20.75 -> 14.44 wmapro_173k 28.52 -> 20.29 / 22.55 -> 16.25 wmapro_271k 30.85 -> 22.52 / 24.34 -> 18.04 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> |
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| android | ||
| apps | ||
| backdrops | ||
| bootloader | ||
| docs | ||
| firmware | ||
| fonts | ||
| icons | ||
| lib | ||
| manual | ||
| packaging | ||
| tools | ||
| uisimulator | ||
| utils | ||
| wps | ||
| .gitattributes | ||
| .gitignore | ||
| .gitreview | ||
__________ __ ___.
Open \______ \ ____ ____ | | _\_ |__ _______ ___
Source | _// _ \_/ ___\| |/ /| __ \ / _ \ \/ /
Jukebox | | ( <_> ) \___| < | \_\ ( <_> > < <
Firmware |____|_ /\____/ \___ >__|_ \|___ /\____/__/\_ \
\/ \/ \/ \/ \/
Build Your Own Rockbox
1. Clone 'rockbox' from git (or extract a downloaded archive).
$ git clone git://git.rockbox.org/rockbox
or
$ tar xJf rockbox.tar.xz
2. Create a build directory, preferably in the same directory as the firmware/
and apps/ directories. This is where all generated files will be written.
$ cd rockbox
$ mkdir build
$ cd build
3. Make sure you have mips/m68k/arm-elf-gcc and siblings in the PATH. Make sure
that you have 'perl' in your PATH too. Your gcc cross compiler needs to be
a particular version depending on what player you are compiling for. These
can be generated using the rockboxdev.sh script in the /tools/ folder of the
source.
$ which arm-elf-eabi-gcc
$ which perl
4. In your build directory, run the 'tools/configure' script and enter what
target you want to build for and if you want a debug version or not (and a
few more questions). It'll prompt you. The debug version is for making a
gdb version out of it. It is only useful if you run gdb towards your target
Archos.
$ ../tools/configure
5. *ploink*. Now you have got a Makefile generated for you.
6. Run 'make' and soon the necessary pieces from the firmware and the apps
directories have been compiled, linked and scrambled for you.
$ make
$ make zip
7. unzip the rockbox.zip on your music player, reboot it and
*smile*.
If you want to build for more than one target, just create several build
directories and create a setup for each target:
$ mkdir build-fuzeplus
$ cd build-fuzeplus
$ ../tools/configure
$ mkdir build-xduoox3
$ cd build-xduoox3
$ ../tools/configure
Questions anyone? Ask on the mailing list or on IRC. We'll be happy to help you!