All modern assemblers have this capability. Older NASM versions
that lack the capability produce code that crashes at runtime,
so it's better to error out during the build process instead.
CC: libav-stable@libav.org
Some awk versions do not treat the result of unary + on a (numeric)
string as numeric, giving wrong results when used in a boolean context
Using unary - instead is logically equivalent works as expected.
Signed-off-by: Mans Rullgard <mans@mansr.com>
This isn't too useful as a normal codec, but can be used in
voip style applications. The decoder updates the noise
generator parameters when a packet is given to it for decoding,
but if called with an empty packet, it generates more noise
according to the last parameters.
Signed-off-by: Martin Storsjö <martin@martin.st>
This adds support for building on Plan 9 x86-32. The compat/plan9
directory contains these items:
- replacements for the 'head' and 'printf' shell commands
- wrapper for main() to disable FPU exceptions
Larger required changes to the system are described in the
documentation.
Signed-off-by: Mans Rullgard <mans@mansr.com>
This allows targets to include special objects when linking
executables without including them in (shared) libraries.
Signed-off-by: Mans Rullgard <mans@mansr.com>
The absence of this function will only give a less informative
string back from our fallback implementation of getnameinfo().
Signed-off-by: Mans Rullgard <mans@mansr.com>
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>
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>
Add a configure function to pull in a compat object and set up
redirects in one operation. This avoids duplicating conditions
across configure and makefiles.
Signed-off-by: Mans Rullgard <mans@mansr.com>
The glibc definitions of INFINITY and NAN do not work with the
tms470 compiler, nor do our usual fallbacks.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Apply flags to work around glibc quirks only if glibc is detected,
and add a few more such flags.
Do not mess with as/ld settings in probe_cc. This is not the
proper place.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Solaris defaults to non-standard utilities (grep, sed, ...) with
proper ones being in /usr/xpg4/bin. Prefixing PATH with this
directory when it exists ensures we get correct variants.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Enable dead store elimination. The last few releases work no worse
with this flag than without. Older versions failed to build some
source files when using this flag.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Now that there is CPU detection in YASM, there will always be one of
inline or external assembly enabled, which obviates the need to fall
back on CPU detection through compiler intrinsics.
Mans Rullgard
Diego Biurrun
Anton Khirnov
James Zern
Martin Storsjö
Michael Kostylev
Derek Buitenhuis
Luca Barbato