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" [e-mail]
To: [e-mail]
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
> [e-mail] 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
>
> Ros-dev mailing list
> [e-mail]
> http://www.reactos.org/mailman/listinfo/ros-dev