lrotr.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 69 行

/****************************************************************************
*
*                            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
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*    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
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*  ========================================================================
*
* Description:  Implementation of _lrotr().
*
****************************************************************************/


#undef __INLINE_FUNCTIONS__
#include "variety.h"
#include <stdlib.h>
#include <limits.h>

extern  unsigned long __lrotr( unsigned long, unsigned );

#if defined(__386__)
#pragma aux __lrotr = "ror eax,cl" parm [eax] [ecx] value [eax] modify [ecx];
#elif defined(M_I86)
#pragma aux __lrotr =   "   and cx,31"\
                        "   jcxz L2"\
                        "L1:ror dx,1"\
                        "   rol dx,1"\
                        "   rcr ax,1"\
                        "   rcr dx,1"\
                        "   dec cx"\
                        "   jne L1"\
                        "L2:"\
                        parm [ax dx] [cx] value [ax dx];
#endif


_WCRTLINK unsigned long _lrotr( unsigned long value, unsigned int shift )
{
#if defined(__386__) || defined(M_I86)
    return( __lrotr( value, shift ) );
#else
    unsigned long   tmp;

    tmp = value;
    value = value >> shift;
    tmp = tmp << ((sizeof( tmp ) * CHAR_BIT) - shift);
    value = value | tmp;
    return( value );
#endif
}