avcodec/dcadec: remove fishy FFMAX()

These where intended to maintain the previous behavior before dca_dmix_code()
but it is unclear (to me) which way is correct and no sample seem to trigger
the case, also they are incomplete for the purprose of error checking

Found-by: Niels Möller <nisse@lysator.liu.se>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avcodec/dcadec: Check dca_dmixtable index

Found-by: Niels Möller <nisse@lysator.liu.se>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
huffyuvdec: clean up macro

It's no longer used inside another specific macro, so rename it.
Also remove duplicated definition and realign code.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
huffyuvdec: trick for plane decoding, 8bits

10496 -> 9105 cycles.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
huffyuvdec: remove superfluous check

An invalid entry already has the property of having a negative number
of bits, so remove the check on the reserved value, and rearrange the
code as a consequence.

346800 decicycles in 422, 262079 runs, 65 skips
168197 decicycles in gray, 262077 runs, 67 skips
Overall time: 7.878s

319076 decicycles in 422, 262096 runs, 48 skips
159875 decicycles in gray, 262057 runs, 87 skips
Overall time: 7.394s

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
huffyuvdec: remove superfluous check in BGR code

Before: 154861 decicycles
After:  152912 decicycles

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
avutil/ppc/intreadwrite: try to fix intreadwrite for ppc64le

Untested due to lack of hardware

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>