We currently only have exported data symbols within libavcodec, but
the concept is easy to extend to other libraries if necessary.
The attribute declaration needs to be in a private header though,
since we can't use CONFIG_SHARED in public installed headers.
Signed-off-by: Martin Storsjö <martin@martin.st>
Previously, the former form always produced a manually aligned,
padded buffer, while the latter can use DECLARE_ALIGNED, if that
amount of stack alignment is supported.
libavutil/internal.h needs to include mem.h, since it uses
the DECLARE_ALIGNED macro.
Signed-off-by: Martin Storsjö <martin@martin.st>
Include macros.h explicitly in common.h so that external code using
FFALIGN does not break. It was already implicitly included through
version.h. Include macros.h in lls.h and internal.h for FFALIGN.
lls.h was including common.h only for FFALIGN and internal.h was
missing the include for FFALIGN. `make checkheaders` did not catch it
because it's an internal header.
The C runtime C99 compatibility had been improved a lot and it now
rejects some of the compatibility defines provided for the older
versions.
Many thanks to Ray for the time spent testing.
Bug-Id: 864
CC: libav-stable@libav.org
Prior to this on msvc/icl there was no handling of deprecated functions
and the deprecated warning was disabled.
After enabling there are a number of warnings relating to the CRT and
the use of the non-secure versions of several functions. Defining
_CRT_SECURE_NO_WARNINGS silences these warnings.
Signed-off-by: Martin Storsjö <martin@martin.st>
Add one copy of the function into each of the libraries, similarly
to what we do for log2_tab. When using static libs, only one
copy of the file_open.o object file gets included, while when
using shared libraries, each of them get a copy of its own.
This fixes DLL builds with a statically linked C runtime, where
each DLL effectively has got its own instance of the C runtime,
where file descriptors can't be shared across runtimes.
On systems not using msvcrt, the function is not duplicated.
Signed-off-by: Martin Storsjö <martin@martin.st>
This used to only be necessary in static builds (when using the
dynamically linked C runtime), since the _imp prefixed symbols do
exist when linking to the actual DLL. When building testprogs,
however, the current library (e.g. libavutil for some of the testprogs)
is linked statically.
This fixes make fate on DLL builds when using the dynamically
linked C runtime.
Signed-off-by: Martin Storsjö <martin@martin.st>
This provides a fallback when building with Yasm enabled, but neither
inline assembly, nor the _mm_empty intrinsic are available or enabled.
Signed-off-by: Diego Biurrun <diego@biurrun.de>
Preventing the use of discouraged or 'insecure' external functions
through defines in an internal header is not a good solution. The
header is not guaranteed to be included universally which makes
overlooking bad use of said functions during review more likely.
There are cases were those functions either are the most straight
forward solution or even have to be used. Using malloc or free is
required if the allocation or release is done by other libraries.
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>
There are cases where strncpy() does exactly what is required.
A blanket ban forces more convoluted solutions to be used in those
cases and has been a cause of bugs.
Signed-off-by: Mans Rullgard <mans@mansr.com>
The only compiler I have that does not define the standard
offsetof() macro is "Bruce's C Compiler", a simple compiler
for producing 8/16-bit 8086 code, usually for use in early
stages of PC booting.
Signed-off-by: Mans Rullgard <mans@mansr.com>
This list is incomplete (we also use UINT16_MAX), so there does
not appear to be any system we care about that needs these.
Signed-off-by: Mans Rullgard <mans@mansr.com>
This macro is only used in two places, both in libavcodec, so this
is a more sensible place for it.
Two small tweaks to the macro are made:
- removing the trailing semicolon
- dropping unnecessary 'volatile' from the x86 asm
Signed-off-by: Mans Rullgard <mans@mansr.com>
With unknown attribute warnings disabled, these checks are no
longer needed. Removing them improves readability while having
no effect on generated code.
Signed-off-by: Mans Rullgard <mans@mansr.com>
