fstrrchr.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 79 行

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*                            Open Watcom Project
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*    This file contains Original Code and/or Modifications of Original
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#include "variety.h"
#include <string.h>

#ifdef  M_I86

extern  char _WCFAR *_fast_strrchr( const char _WCFAR *, char );

#pragma aux    _fast_strrchr = \
        0xb9 0xff 0xff  /* mov cx,ffffh */ \
        0x30 0xc0       /* xor al,al */ \
        0xf2 0xae       /* repne scasb */ \
        0xf7 0xd1       /* not cx */ \
        0x4f            /* dec di */ \
        0x88 0xd8       /* mov al,bl */ \
        0xfd            /* std */ \
        0xf2 0xae       /* repne scasb */ \
        0xfc            /* cld */ \
        0x75 0x04       /* jne L1 */ \
        0x89 0xf9       /* mov cx,di */ \
        0x41            /* inc cx */ \
        0xa9            /* hide 2 bytes */ \
        0x8e 0xc1       /* L1: mov es,cx */ \
        parm caller [es di] [bl] \
        value [es cx] \
        modify exact [es cx ax di];
#endif

/* Locate the last occurrence of c in the string pointed to by s.
   The terminating null character is considered to be part of the string.
   If the character c is not found, NULL is returned.
*/

_WCRTLINK char _WCFAR *_fstrrchr( const char _WCFAR *s, int c )
    {
#if defined(M_I86)
        return( _fast_strrchr( s, c ) );
#else
        char _WCFAR *p;

        p = NULL;       /* assume c will not be found */
        do {
            if( *s == c ) p = (char _WCFAR *)s;
        } while( *s++ != '\0' );
        return( p );
#endif
    }