[Ffmpeg-devel] uint_fast64_t in vorbis.c

Dave Dodge dododge
Wed Jun 8 02:01:36 CEST 2005

On Tue, Jun 07, 2005 at 04:21:50PM +0200, Alexander Strasser wrote:
> Fran?ois Revol wrote:
> > What could that thing be useful for anyway ??
>   It's the only way you can assure the type has the minimum size
> you want and is optionally bigger so you won't end up using 8bit
> types all the way on a 32bit architecture for example.

The gist of it:

  uint_least64_t guarantees to be the smallest unsigned integer type
  of at least 64 bits.

  uint_fast64_t guarantees to be the fastest unsigned integer type of
  at least 64 bits.

You can optimize your type choice for size or speed, and make it clear
in your code what you're asking for.  There are also "int_"
variations, as well as sizes of 8, 16, and 32.  C99 requires all of
these typedefs as part of <stdint.h> for all implementations.

There's also the exact-width typedefs such as uint64_t, which are
required if the implementation can support a type of exactly that

                                                  -Dave Dodge

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