Also retroactively add a changelog entry to the 9beta1 list
for general MSVC support, which was present there already.
Signed-off-by: Martin Storsjö <martin@martin.st>
This requires the makedef perl script by Derek, from the
c89-to-c99 repo. That scripts produces a .def file, listing
the symbols to be exported, based on the gcc version scripts
and the built object files.
To properly load non-function symbols from DLL files, the
data symbol declarations need to have the attribute
__declspec(dllimport) when building the calling code. (On mingw,
the linker can fix this up automatically, which is why it has not
been an issue so far. If this attribute is omitted, linking
actually succeeds, but reads from the table will not produce the
desired results at runtime.)
MSVC seems to manage to link DLLs (and run properly) even if
this attribute is present while building the library itself
(which normally isn't recommended) - other object files in the
same library manage to link to the symbol (with a small warning
at link time, like "warning LNK4049: locally defined symbol
_avpriv_mpa_bitrate_tab imported" - it doesn't seem to be possible
to squelch this warning), and the definition of the tables
themselves produce a warning that can be squelched ("warning C4273:
'avpriv_mpa_bitrate_tab' : inconsistent dll linkage, see previous
definition of 'avpriv_mpa_bitrate_tab').
In this setup, mingw isn't able to link object files that refer to
data symbols with __declspec(dllimport) without those symbols
actually being linked via a DLL (linking avcodec.dll ends up with
errors like "undefined reference to `__imp__avpriv_mpa_freq_tab'").
The dllimport declspec isn't needed at all in mingw, so we simply
choose not to declare it for other compilers than MSVC that requires
it. (If ICL support later requires it, the condition can be extended
later to include both of them.)
This also implies that code that is built to link to a certain
library as a DLL can't link to the same library as a static library.
Therefore, we only allow building either static or shared but not
both at the same time. (That is, static libraries as such can be,
and actually are, built - this is used for linking the test tools to
internal symbols in the libraries - but e.g. libavformat built to
link to libavcodec as a DLL cannot link statically to libavcodec.)
Also, linking to DLLs is slightly different from linking to shared
libraries on other platforms. DLLs use a thing called import
libraries, which is basically a stub library allowing the linker
to know which symbols exist in the DLL and what name the DLL will
have at runtime.
In mingw/gcc, the import library is usually named libfoo.dll.a,
which goes next to a static library named libfoo.a. This allows
gcc to pick the dynamic one, if available, from the normal -lfoo
switches, just as it does for libfoo.a vs libfoo.so on Unix. On
MSVC however, you need to literally specify the name of the import
library instead of the static library.
Signed-off-by: Martin Storsjö <martin@martin.st>
This table doesn't need to be shared with libavformat any longer.
Add mpeg12 to the name to make it less ambiguous, while renaming it.
Signed-off-by: Martin Storsjö <martin@martin.st>
This avoids having to share this table across the library
boundaries.
This shared table used to be problematic, if always declaring
all exported data symbols with the dllimport attribute (even
while building that same library), since it needs to be a
link-time constant when it is used in AVCodec declarations
(in mpeg12enc.c).
Signed-off-by: Martin Storsjö <martin@martin.st>
The name mingw32 as target OS is both misleading, and very little
of the target OS specific settings actually match.
Since the target OS default is set based on uname, the default
(which on MSYS is set to mingw) is overridden by --toolchain=msvc.
Signed-off-by: Martin Storsjö <martin@martin.st>
* qatar/master:
mips64: mark hi/lo registers clobbered in MAC64/MLS64 macros
fate: list lavfi tests in a makefile
Conflicts:
configure
tests/Makefile
Merged-by: Michael Niedermayer <michaelni@gmx.at>
* commit '36ac9a16a19a365ce58cc871484c20cffe9b6401':
fate: dependencies for seek tests
fate: handle lavf test dependencies entirely in make
Conflicts:
configure
tests/Makefile
Merged-by: Michael Niedermayer <michaelni@gmx.at>
* commit '292d1e78743855404c7d07e3e7cb3f9c9ae6275b':
fate: dependencies for acodec tests
fate: dependencies for vsynth tests
fate: add macros useful for conditionally enabling things
libmp3lame: resize the output buffer if needed
Conflicts:
tests/fate/acodec.mak
tests/fate/vcodec.mak
Merged-by: Michael Niedermayer <michaelni@gmx.at>
This seemed to assume that one never used writing avio unless
muxers or networking was enabled.
This ifdef is a remnant since 8fa641f8.
Signed-off-by: Martin Storsjö <martin@martin.st>
This fixes the following error:
./configure: eval: line 417: syntax error near unexpected token `-lcdio_cdda'
[...]
Broken by 66a1ccd74 when doing, e.g., ./configure --enable-gpl --enable-libcdio.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
