forked from KolibriOS/kolibrios
158 lines
5.4 KiB
C
158 lines
5.4 KiB
C
/****************************************************************************
|
|
*
|
|
* 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 "widechar.h"
|
|
#include <ctype.h>
|
|
#include <string.h>
|
|
|
|
#if defined(__WIDECHAR__)
|
|
extern size_t wcslen( const CHAR_TYPE * );
|
|
#endif
|
|
|
|
#if defined(M_I86) && !defined(__WIDECHAR__)
|
|
|
|
/*
|
|
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 *, char _WCFAR * );
|
|
|
|
#if defined(__SMALL_DATA__)
|
|
#pragma aux fast_rev = \
|
|
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 */\
|
|
parm caller [si] [es di] \
|
|
value [ax] \
|
|
modify [si cx ax di];
|
|
#else
|
|
#pragma aux fast_rev = \
|
|
0x1e /* push ds */ \
|
|
0x8e 0xda /* mov ds,dx */ \
|
|
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 [dx si] [es di] \
|
|
value [ax] \
|
|
modify [si cx ax di];
|
|
#endif
|
|
|
|
#endif
|
|
|
|
|
|
_WCRTLINK CHAR_TYPE *__F_NAME(strrev,_wcsrev) ( CHAR_TYPE *str ) { /* reverse characters in string */
|
|
#if defined(M_I86) && !defined(__WIDECHAR__)
|
|
fast_rev( str, (char _WCFAR *) str );
|
|
return( str );
|
|
#else
|
|
CHAR_TYPE *p1;
|
|
CHAR_TYPE *p2;
|
|
CHAR_TYPE c1;
|
|
CHAR_TYPE c2;
|
|
|
|
p1 = str;
|
|
p2 = p1 + __F_NAME(strlen,wcslen)( p1 ) - 1;
|
|
while( p1 < p2 ) {
|
|
c1 = *p1;
|
|
c2 = *p2;
|
|
*p1 = c2;
|
|
*p2 = c1;
|
|
++p1;
|
|
--p2;
|
|
}
|
|
return( str );
|
|
#endif
|
|
}
|