[vorbis-dev] optimization patches

[Segher Boessenkool]

Well, here you are. 24k; sorry if I'm not supposed to put this size
things in your mailbox, didn't know where else to put it. And you
all are subscribed to vorbis-dev, after all.

I'm not that good at breaking patches apart, so it's one big patch.
Sorry.

Overview:

configure.in
        make profiling easier & more useful

decoder-example.c
        (#if 0'ed) dither output; sounds a lot more "open", but
        should be coloured dither. Someone else please step in. (The
        dither could be applied before the mdct, but we have to know
        the amplification. No problem with decoder_example, but it is
        in the general case).

codebook.[ch]
bitwise.[ch]
bookinternal.h
sharedbook.c
        decode the first N bits of a huffman word in one step via table
        look up.
        The huffman decoding could be much more efficient (i.e., no
        decode tree necessary -> saves a lot of cache, and decoding
        time O(log log N) instead of O(log N), where N is alphabet
        size), if the huffman tree would be left (or right; I prefer
        left) aligned. Ask me for pointers if you need convincing.
        The code I submit now could be more clean, I know. Seems to
        work though. Weird.

        unrolled && rerolled the decodevs loops.

envelope.c
        if (fabs(...) < min) creates horrible assembler (gcc 2.95, x86),
        so changed to  if (... < min && ... > -min). muchos faster.

lsp.c
        put the fromdB() before linearmap

cales.h
        todB_nn() for non-negative values. fabs() is horror.

Added some prefixes to pack(), inverse(), et. al. (i.e., time0_pack() etc.)
Think I still forgot some.

I don't think you'll want to apply all of this, oh, especially not the
debug output :-).

Have some fun,

Segher


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