Up until now, initializing the dca VLC tables uses ff_init_vlc_sparse()
with length tables of type uint8_t and code tables of type uint16_t
(except for the LBR tables, which uses length and symbols of type
uint8_t; these tables are interleaved). In case of the quant index
codebooks these arrays were accessed via tables of pointers to the
individual tables.
This commit changes this: First, we switch to ff_init_vlc_from_lengths()
to replace the uint16_t code tables by uint8_t symbol tables
(this necessitates ordering the tables from left-to-right in the tree
first). These symbol tables are interleaved with the length tables.
Furthermore, these tables are combined in order to remove the table of
pointers to individual tables, thereby avoiding relocations (for x64
elf systems this amounts to 96*24B = 2304B saved in .rela.dyn) and
saving 1280B from .data.rel.ro (for 64bit systems). Meanwhile the
savings in .rodata amount to 2709 + 2 * 334 = 3377B. Due to padding
the actual savings are higher: The ELF x64 ABI requires objects >= 16B
to be padded to 16B and lots of the tables have 2^n + 1 elements
of these were from replacing uint16_t codes with uint8_t symbols;
the rest was due to the fact that combining the tables eliminated
padding (the ELF x64 ABI requires objects >= 16B to be padded to 16B
and lots of the tables have 2^n + 1 elements)). Taking this into
account gives savings of 4548B. (GCC by default uses an even higher
alignment (controlled by -malign-data); for it the savings are 5748B.)
These changes also necessitated to modify the init code for
the encoder tables.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Up until now, the encoder used the same tables that the decoder
uses to create its VLCs. These have the downside of requiring
the encoder to offset the tables at runtime as well as having
to read from separate tables for the length as well as the code
of the symbol to encode. The former are uint8_t, the latter uint16_t,
so using a joint table would require padding, but this doesn't
matter when these tables are generated at runtime, because they
live in the .bss segment.
Also move these init functions as well as the functions that
actually use them to dcaenc.c, because they are encoder-specific.
This also allows to remove an inclusion of PutBitContext from
dcahuff.h (and indirectly from all dca-decoder files).
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
It increases the size of one VLC from two to three bits, thereby
requiring four more VLCEntries (16 bytes .bss), but it allows to
inline the number of bits used when reading them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
The ff_dca_vlc_transition_mode VLCs don't use an offset at all,
so just use ordinary VLCs for them.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
In C, qualifiers for arrays are broken:
const VLC_TYPE (*foo)[2] is a pointer to an array of two const VLC_TYPE
elements and unfortunately this is not compatible with a pointer
to a const array of two VLC_TYPE, because the latter does not exist
as array types are never qualified (the qualifier applies to the base
type instead). This is the reason why get_vlc2() doesn't accept
a const VLC table despite not modifying the table at all, as
there is no automatic conversion from VLC_TYPE (*)[2] to
const VLC_TYPE (*)[2].
Fix this by using a structure VLCElem for the VLC table.
This also has the advantage of making it clear which
element is which.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Some of these were made possible by moving several common macros to
libavutil/macros.h.
While just at it, also improve the other headers a bit.
Reviewed-by: Martin Storsjö <martin@martin.st>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
