The code was written in 2012, but seems to have been broken
for just as long. Compilation is broken on every MIPS/MIPS64
system with an FPU (which the code depends on).

The fixed decoder derives the values from floats anyway.

Unfortunately, although it's a purely decode function, it does
need to be templated.

All tables now initialized by aac/aacdec_fixed|float

Small cleanup to reduce number of arguments.

The function is called only internally in DSP, so we do not
need to expose it.

apply_ltp on MIPS uses this function, but due to the function
being just a glue function with no real optimizations,
duplicate it there.

Preparation to move all table init and support windowing functions.

Brings it in line with dequantization.

Eliminates using templated values in function definition.

Allows to template away dequantization.

To be used to abstract away DSP functions.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

This is possible now that both AAC decoders share the same
context.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

Up until now, there was one AACDecContext for the fixed
and one for the floating point decoder. These differed
mostly in certain arrays which were int for the fixed-point
and float for the floating point decoder; there were also
differences in corresponding function pointers.

Yet in order to deduplicate the enormous amount of currently
duplicated code between the float and the fixed-point decoder,
one needs common contexts. Given that int and float have the
same size on all common systems, this commit replaces these
arrays by unions of int arrays and of float arrays. The names
of these arrays have been chosen to be compatible with
AAC_RENAME().
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

sizeof(PredictorState) is different for the floating-point and
the fixed-point AAC decoders; this is an obstacle for deduplicating
code between these decoders. So don't include this array in
SingleChannelElement, instead add a union of pointers to the
fixed-point PredictorState and the floating-point PredictorState.
The actual arrays are part of the extended ChannelElement
to be allocated by ff_aac_sbr_ctx_alloc_init(); it also
sets the pointers.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

Up until now, AACDecContext included pointers to one of these
contexts depending upon USE_FIXED. Yet deduplicating
the common parts of the float and fixed-point AAC decoders
needs common structures, so we put both of these pointers
in a union.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

The AAC fixed-point and floating-point decoders have
a lot of duplicated code; the main obstacle to
deduplicating it is that several structures with the
same name are actually different types, because
they contain INTFLOATs (int or float) and AAC_FLOATs
(SoftFloat or float). SoftFloat and float typically
have different sizes, so dealing with it is the more
complicated of the two.

AAC_FLOAT is mainly used in the sbr code and structures,
so one can still deduplicate the code by only exposing
the common part of ChannelElement (without SBR context)
to the common decoder part. One prerequisite of this
is to move allocating the whole ChannelElement to
code that will stay unduplicated. It is most natural
to move said allocation to ff_aac_sbr_ctx_init().
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

Each ChannelElement contains exactly one SpectralBandReplication
structure; the latter structure contains lots of buffers
whose size depend upon USE_FIXED (i.e. AAC_FLOAT arrays).
This complicates deduplicating the parts of the AAC decoder
that are duplicated between the fixed-point and the floating
point decoder.

In order to fix this, the SpectralBandReplication structure
will be moved from the part of ChannelElement visible to
the common code. Therefore the ff_aac_sbr_* functions
are ported to accept a ChannelElement*; they will then have
to translate that to the corresponding SpectralBandReplication*
themselves (which is possible, because there are floating-point
and fixed-point versions of these functions).

While just at it, also ensure that these functions are properly
namespaced.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

Future AAC changes remove the need to include this header.

Start to clean up the decoder.
Also renames a confusingly named file.

has_b_frames used in decoder for size of the frame
reordering buffer, and we don't used the max_b_frames
in decoder.
Signed-off-by: Jun Zhao <barryjzhao@tencent.com>