Messages in this thread | ![/](/images/icornerl.gif) | | Date | Sun, 03 Apr 2005 14:30:11 +0200 | From | Dag Arne Osvik <> | Subject | Re: Use of C99 int types |
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Stephen Rothwell wrote:
>On Sun, 03 Apr 2005 13:55:39 +0200 Dag Arne Osvik <da@osvik.no> wrote: > > >>I've been working on a new DES implementation for Linux, and ran into >>the problem of how to get access to C99 types like uint_fast32_t for >>internal (not interface) use. In my tests, key setup on Athlon 64 slows >>down by 40% when using u32 instead of uint_fast32_t. >> >> > >If you look in stdint.h you may find that uint_fast32_t is actually >64 bits on Athlon 64 ... so does it help if you use u64? > > >
Yes, but wouldn't it be much better to avoid code like the following, which may also be wrong (in terms of speed)?
#ifdef CONFIG_64BIT // or maybe CONFIG_X86_64? #define fast_u32 u64 #else #define fast_u32 u32 #endif
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