lrotl.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 68 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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*  ========================================================================
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* Description:  Implementation of _lrotl().
*
****************************************************************************/


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

extern  unsigned long __lrotl( unsigned long, unsigned );

#if defined(__386__)
#pragma aux __lrotl = "rol eax,cl" parm [eax] [ecx] value [eax] modify [ecx];
#elif defined(M_I86)
#pragma aux __lrotl =   "    and cx,31"\
                        "    je  short L2"\
                        "L1: adc ax,ax"\
                        "    adc dx,dx"\
                        "    adc ax,0"\
                        "    dec cx"\
                        "    jne L1"\
                        "L2:" \
                        parm [ax dx] [cx] value [ax dx];
#endif


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

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