[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 at ev1.net>
To: <ros-dev at 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 at 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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