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Clib string & memory functions

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git-svn-id: svn://kolibrios.org@553 a494cfbc-eb01-0410-851d-a64ba20cac60
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Sergey Semyonov (Serge)
2007-06-26 00:54:22 +00:00
parent d5f66e011c
commit 836c97f0ac
162 changed files with 11855 additions and 0 deletions
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programs/develop/open watcom/trunk/clib/string/fstrrev.c Normal file
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/****************************************************************************
*
* Open Watcom Project
*
* Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
*
* ========================================================================
*
* This file contains Original Code and/or Modifications of Original
* Code as defined in and that are subject to the Sybase Open Watcom
* Public License version 1.0 (the 'License'). You may not use this file
* except in compliance with the License. BY USING THIS FILE YOU AGREE TO
* ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
* provided with the Original Code and Modifications, and is also
* available at www.sybase.com/developer/opensource.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
* ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
* NON-INFRINGEMENT. Please see the License for the specific language
* governing rights and limitations under the License.
*
* ========================================================================
*
* Description: WHEN YOU FIGURE OUT WHAT THIS FILE DOES, PLEASE
* DESCRIBE IT HERE!
*
****************************************************************************/
#include "variety.h"
#include <ctype.h>
#include <string.h>
#ifdef M_I86
/*
explanation of algorithm:
(1) reverse as much of the string as possible as words
(2) after main loop: reverse residual inner string (0-3 bytes)
the string falls into one of these forms:
{ prefix_word }* { suffix_word }*
{ prefix_word }* middle_byte { suffix_word }*
{ prefix_word }* pre_middle_byte post_middle_byte { suffix_word }*
{ prefix_word }* pre_middle_byte middle_byte post_middle_byte { suffix_word }*
we only have to swap two bytes when:
len & 2 != 0 is true (ie. the carry is set after second shr cx,1)
*****************************************************************************
WARNING: the code in the L1: ... reverse loop cannot modify the carry flag
*****************************************************************************
*/
extern void fast_rev( char _WCFAR * );
#pragma aux fast_rev = \
0x1e /* push ds */\
0x8e 0xc1 /* mov es,cx */\
0x8e 0xd9 /* mov ds,cx */\
0x89 0xfe /* mov si,di */\
0xb9 0xff 0xff /* mov cx,ffff */\
0x30 0xc0 /* xor al,al */\
0xf2 0xae /* repne scasb */\
0xf7 0xd1 /* not cx */\
0x49 /* dec cx */\
0xfd /* std */\
0x83 0xef 0x03 /* sub di,3 */\
0xd1 0xe9 /* shr cx,1 */\
0xd1 0xe9 /* shr cx,1 */\
0xe3 0x0d /* jcxz L2 */\
0x8b 0x05 /* L1:mov ax,[di] */\
0x86 0xe0 /* xchg ah,al */\
0x87 0x04 /* xchg ax,[si] */\
0x86 0xe0 /* xchg ah,al */\
0xab /* stosw */\
0x46 /* inc si */\
0x46 /* inc si */\
0xe2 0xf3 /* loop L1 */\
0x73 0x07 /* L2:jnc L3 */\
0x47 /* inc di */\
0x8a 0x05 /* mov al,[di] */\
0x86 0x04 /* xchg al,[si] */\
0x88 0x05 /* mov [di],al */\
0xfc /* L3:cld */\
0x1f /* pop ds */\
parm caller [cx di] \
modify [si cx ax di es];
#endif
_WCRTLINK char _WCFAR *_fstrrev( char _WCFAR *str ) /* reverse characters in string */
{
#if defined(M_I86)
fast_rev( str );
return( str );
#else
char _WCFAR *p1;
char _WCFAR *p2;
char c1;
char c2;
p1 = str;
p2 = p1 + _fstrlen( p1 ) - 1;
while( p1 < p2 ) {
c1 = *p1;
c2 = *p2;
*p1 = c2;
*p2 = c1;
++p1;
--p2;
}
return( str );
#endif
}