[Ffmpeg-devel] [PATCH] qcelp codec supporrt
Thu Dec 14 02:46:07 CET 2006
On Wed, Dec 13, 2006 at 11:18:02PM +0000, M?ns Rullg?rd wrote:
> >> > + *p++ = (pkt.data[i] >> 8) & 0xff;
> >> > + *p++ = pkt.data[i] & 0xff;
> >> the & 0xff isnt needed
> > I appended it because I thought signed to unsigned conversion
> > between two values of the different storage size is not
> > defined in the C spefication.
> Conversion to unsigned is well-defined. Conversion to signed is only
> defined when the value is within the range of the target type. This
> is mostly because the C standard doesn't specify how negative numbers
> are represented. Apparently there were some machines in the distant
> past that used one's complement to represent negative numbers.
Because their creators failed MATH 101... For all practical purposes,
all arithmetic is twos complement and signed truncation is well-defined.
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