Re: [ros-dev] [ros-diffs] [greatlrd] 23826: Wrote RtlUshotByteSwap RtlUlongByteSwap and RtlUlonglongByteSwap to asm code. but we need a C api for header to linking it right. Put the asm version to i386

[Magnus Olsen]

Hi
Royce3
alex solv it
and he also wrote some other rtl* to asm
with some commit.

----- Original Message ----- 
From: "Reuel ben Yisrael" <reuel(a)ev1.net>
To: <ros-dev(a)reactos.org>
Sent: Wednesday, August 30, 2006 11:29 PM
Subject: Re: [ros-dev] [ros-diffs] [greatlrd] 23826: Wrote RtlUshotByteSwap
RtlUlongByteSwap and RtlUlonglongByteSwap to asm code. but we need a C api
for header to linking it right. Put the asm version to i386


>   greatlrd(a)svn.reactos.org wrote:
>
>  >Author: greatlrd
>  >Date: Thu Aug 31 01:17:53 2006
>  >New Revision: 23826
>  >
>  >URL: http://svn.reactos.org/svn/reactos?rev=23826&view=rev
>  >Log:
>  >Wrote  RtlUshotByteSwap RtlUlongByteSwap and  RtlUlonglongByteSwap to asm
code.
>   >   but we need a C api for header to linking it
> right. Put the asm 
version to i386
> >  
> >  
>  sure there must be away to avoid this double-function-call overhead?
>
>  >+.globl _UlongByteSwap
>  >+
>  >+.intel_syntax noprefix
>  >+
>  >+/* FUNCTIONS 
***************************************************************/
> >  +
> > +_UlongByteSwap:
> > +                       push  ebp          // save base
> > +                       mov   ebp,esp      // move stack to base
> > +                       mov   eax,[ebp+8]  // load the ULONG
> > +                       bswap eax          // swap the ULONG
> > +                       pop   ebp          // restore the base
> > +                       ret
> >
> >  
>  this should work:
>
>  _UlongByteSwap:
>                         mov   eax,[esp+8]  // load the ULONG
>                         bswap eax          // swap the ULONG
>                         ret
>
>
>  >+.globl _UlonglongByteSwap
>  >+
>  >+.intel_syntax noprefix
>  >+
>  >+/* FUNCTIONS 
***************************************************************/
>   >+
>  >+_UlonglongByteSwap:
>  >+                       push  ebp          // save base
>  >+                       mov   ebp,esp      // move stack to base
>  >+                       mov   edx,[ebp+8]  // load the higher part of
ULONGLONG
>   >+                       mov   eax,[ebp+12] // load
> the lower part of 
ULONGLONG
> >  +              
> >         bswap edx          // swap the higher part
> > +                       bswap eax          // swap the lower part
> > +                       pop   ebp          // restore the base
> > +                       ret
> >
> >  
>  _UlonglongByteSwap:
>                         mov   edx,[esp+8]  // load the higher part of 
ULONGLONG
>                          mov   eax,[esp+12] // load the
> lower part of 
ULONGLONG
>                          bswap edx          // swap the
> higher part
>                         bswap eax          // swap the lower part
>                         ret
>
>  >+_UshortByteSwap:
>  >+                       push  ebp          // save base
>  >+                       mov   ebp,esp      // move stack to base
>  >+                       mov   eax,[ebp+8]  // load the USHORT
>  >+                       bswap eax          // swap the USHORT, xchg is 
slow so
we use bswap with rol
> >  +              
> >         rol   eax,16       // make it USHORT
> > +                       pop   ebp          // restore the base
> > +                       ret
> >
> >  
>  _UshortByteSwap:
>                         mov   eax,[esp+8]  // load the USHORT
>                         bswap eax          // swap the USHORT, xchg is slow 
so we
use bswap with rol
>                          rol   eax,16       // make it
> USHORT
>                         ret
>
>
>  or to save a byte...
>
>  _UshortByteSwap:
>                         mov   ebx,[esp+8]  // load the USHORT
>                         mov   al, bh
>                         mov   ah, bl
>                         ret
>
>
>
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