[Speex-dev] New function for manipulating SpeexBits

[Miles, Stewart]

speex_bits_init_buffer(), clears the buffer. 

-----Original Message-----
From: Jean-Marc Valin [mailto:jean-marc.valin at usherbrooke.ca] 
Sent: Saturday, December 09, 2006 11:20 AM
To: Miles, Stewart
Cc: speex-dev at xiph.org
Subject: Re: [Speex-dev] New function for manipulating SpeexBits

How's that different from the current speex_bits_init_buffer()?

	Jean-Marc

Miles, Stewart a écrit :
> It would be nice to have the following function added to the speex 
> bits...
> 
> void speex_bits_read_from_buffer(
>     SpeexBits * const bits, 
>     void      * const buff, 
>     const int         buf_size)
> {
>     bits->bytes    = (char*)buff;
>     bits->buf_size = buf_size;
>     bits->nbBits   = buf_size << 3;
>     bits->bytePtr  = 0;
>     bits->bitPtr   = 0;
>     bits->owner    = 0;
>     bits->overflow = 0;
> }
> 
> ... so a bitstream can be assigned to a SpeexBits structure for 
> processing by a decoder rather than unnecessarily copying the data.
> 
> 
> As an aside, I'm working on a certain high profile embedded game's 
> console at the moment and one of the performance problems is due to 
> all of the copying speex performs without calling memcpy.  Although 
> memcpy() is generally a pretty nasty function when copying very small 
> blocks of data (< 128 bits) from a performance point of view it does 
> have significant advantages when copying longer runs as some 
> architectures are optimized for 128bit memory access others 64bit 
> access etc, 8 bit stores can actually result in code that's up to 16 
> times slower (in the case of the 128bit architecture).
> 
> Thanks, keep up the good work
> 
> Stewart Miles
> http://www.mobygames.com/developer/sheet/view/developerId,62864/
> _______________________________________________
> Speex-dev mailing list
> Speex-dev at xiph.org
> http://lists.xiph.org/mailman/listinfo/speex-dev
> 
> 
>