[FFmpeg-cvslog] r14897 - trunk/libavcodec/acelp_filters.c

[Michael Niedermayer]

On Fri, Aug 22, 2008 at 12:42:04AM +0100, M?ns Rullg?rd wrote:
> michael <subversion at mplayerhq.hu> writes:
> 
> > Author: michael
> > Date: Fri Aug 22 01:25:41 2008
> > New Revision: 14897
> >
> > Log:
> > Remove mathops.h dependancy.
> 
> The purpose of mathops.h is to allow CPU-specific instructions to be
> used for common operations.  Not using it when possible is similar to
> not using dsputil.  Is there a specific reason the optimised macros
> are unsuitable in this file?

Several points
  the first line can be simplified to 
  tmp = (hpf_f[0]* 3959LL)>>11;
  but the shift is fixed per file when mathops.h is used

  vladimirs comments indicated that the hpf variables need 26 bits
  in which case the code can be simplified to
  tmp  = ( 31*hpf_f[0] + ((hpf_f[0]*-9)>>7))>>4
  tmp += (-15*hpf_f[1] + ((hpf_f[1]*13)>>9))>>4;
  which avoids the 64bit ops ...
  additionally the >>4 can be done after the summing of the 2 though
  that would not be bit exact
  The main reason why i didnt commit it was that i just found out that
  the code contains a claim from vladimir that cliping to 16bit after
  a right shift of 12 bits is required thus completely contradicting
  the first comment of these fitting in 26bits.
  Thats also a good example why i flamed him, his code is a total mess
  and the comments are only costing the reader extra time as half are
  wrong.

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Its not that you shouldnt use gotos but rather that you should write
readable code and code with gotos often but not always is less readable
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