5182befa49
This makes sure that labels for data symbols directly after functions get properly 4-byte-aligned (when the source is assembled in thumb mode). Previously, if declaring a data symbol directly after a function, the symbol could end up pointing to the unaligned address (if the total size of the thumb function didn't end up being a multiple of 4). The data in the symbol itself ended up aligned, but the symbol pointed to the preceding unaligned position. That is, a source file looking like this: --- ... ENDP symbol DCD 0x12345678 --- could end up being assembled into symbol: xxxxx2: 0000 xxxxx4: 5678 xxxxx6: 1234 (This doesn't happen if the symbol label is on the same line as the DCD directive.) By adding an ALIGN 4 directly after the ENDP we make sure the symbol itself gets aligned properly. This isn't an issue with the original, untranslated arm source, since it only is built in arm mode where all instructions are 4 byte, and since the gnu assembler automatically adds the padding before the symbol even in thumb mode. Change-Id: Iadbeebd656b0197e423e79a12a7d3ef8859cf445
vpx Multi-Format Codec SDK
README - 1 August 2013
Welcome to the WebM VP8/VP9 Codec SDK!
COMPILING THE APPLICATIONS/LIBRARIES:
The build system used is similar to autotools. Building generally consists of
"configuring" with your desired build options, then using GNU make to build
the application.
1. Prerequisites
* All x86 targets require the Yasm[1] assembler be installed.
* All Windows builds require that Cygwin[2] be installed.
* Building the documentation requires PHP[3] and Doxygen[4]. If you do not
have these packages, you must pass --disable-install-docs to the
configure script.
* Downloading the data for the unit tests requires curl[5] and sha1sum.
sha1sum is provided via the GNU coreutils, installed by default on
many *nix platforms, as well as MinGW and Cygwin. If coreutils is not
available, a compatible version of sha1sum can be built from
source[6]. These requirements are optional if not running the unit
tests.
[1]: http://www.tortall.net/projects/yasm
[2]: http://www.cygwin.com
[3]: http://php.net
[4]: http://www.doxygen.org
[5]: http://curl.haxx.se
[6]: http://www.microbrew.org/tools/md5sha1sum/
2. Out-of-tree builds
Out of tree builds are a supported method of building the application. For
an out of tree build, the source tree is kept separate from the object
files produced during compilation. For instance:
$ mkdir build
$ cd build
$ ../libvpx/configure <options>
$ make
3. Configuration options
The 'configure' script supports a number of options. The --help option can be
used to get a list of supported options:
$ ../libvpx/configure --help
4. Cross development
For cross development, the most notable option is the --target option. The
most up-to-date list of supported targets can be found at the bottom of the
--help output of the configure script. As of this writing, the list of
available targets is:
armv5te-android-gcc
armv5te-linux-rvct
armv5te-linux-gcc
armv5te-none-rvct
armv6-darwin-gcc
armv6-linux-rvct
armv6-linux-gcc
armv6-none-rvct
armv7-android-gcc
armv7-darwin-gcc
armv7-linux-rvct
armv7-linux-gcc
armv7-none-rvct
armv7-win32-vs11
armv7-win32-vs12
mips32-linux-gcc
ppc32-darwin8-gcc
ppc32-darwin9-gcc
ppc32-linux-gcc
ppc64-darwin8-gcc
ppc64-darwin9-gcc
ppc64-linux-gcc
sparc-solaris-gcc
x86-android-gcc
x86-darwin8-gcc
x86-darwin8-icc
x86-darwin9-gcc
x86-darwin9-icc
x86-darwin10-gcc
x86-darwin11-gcc
x86-darwin12-gcc
x86-darwin13-gcc
x86-linux-gcc
x86-linux-icc
x86-os2-gcc
x86-solaris-gcc
x86-win32-gcc
x86-win32-vs7
x86-win32-vs8
x86-win32-vs9
x86-win32-vs10
x86-win32-vs11
x86-win32-vs12
x86_64-darwin9-gcc
x86_64-darwin10-gcc
x86_64-darwin11-gcc
x86_64-darwin12-gcc
x86_64-darwin13-gcc
x86_64-linux-gcc
x86_64-linux-icc
x86_64-solaris-gcc
x86_64-win64-gcc
x86_64-win64-vs8
x86_64-win64-vs9
x86_64-win64-vs10
x86_64-win64-vs11
x86_64-win64-vs12
universal-darwin8-gcc
universal-darwin9-gcc
universal-darwin10-gcc
universal-darwin11-gcc
universal-darwin12-gcc
universal-darwin13-gcc
generic-gnu
The generic-gnu target, in conjunction with the CROSS environment variable,
can be used to cross compile architectures that aren't explicitly listed, if
the toolchain is a cross GNU (gcc/binutils) toolchain. Other POSIX toolchains
will likely work as well. For instance, to build using the mipsel-linux-uclibc
toolchain, the following command could be used (note, POSIX SH syntax, adapt
to your shell as necessary):
$ CROSS=mipsel-linux-uclibc- ../libvpx/configure
In addition, the executables to be invoked can be overridden by specifying the
environment variables: CC, AR, LD, AS, STRIP, NM. Additional flags can be
passed to these executables with CFLAGS, LDFLAGS, and ASFLAGS.
5. Configuration errors
If the configuration step fails, the first step is to look in the error log.
This defaults to config.log. This should give a good indication of what went
wrong. If not, contact us for support.
SUPPORT
This library is an open source project supported by its community. Please
please email webm-discuss@webmproject.org for help.