source: svn/trunk/newcon3bcm2_21bu/dta/src/bootloader/rsa/mpclshift.c

/***************************************************************************
 *     Copyright (c) 2002-2009, Broadcom Corporation
 *     All Rights Reserved
 *     Confidential Property of Broadcom Corporation
 *
 *  THIS SOFTWARE MAY ONLY BE USED SUBJECT TO AN EXECUTED SOFTWARE LICENSE
 *  AGREEMENT  BETWEEN THE USER AND BROADCOM.  YOU HAVE NO RIGHT TO USE OR
 *  EXPLOIT THIS MATERIAL EXCEPT SUBJECT TO THE TERMS OF SUCH AN AGREEMENT.
 *
 * Filename: mpclshift.c
 *
 ***************************************************************************/
/* 
 * Multiple-Precision Modular Arithmetic Routines
 *
 *
 * Change log:  07/17/02 -      Created.
 *              07/29/02 -      Split functions mpcopy(), mplong2mp(),
 *                              mpzero(), newabs() into separate files.
 *              07/30/02 - newabs & sign support removed definitely.
 */


#include "mp2.h"

/* global vars */

/* optimization: do not swap bytes in word, assume input is given
 * as little-endian 32-bit words. */ 
#undef INPUT_IS_NOT_LITTLE_ENDIAN_WORD32_ARRAY

/* Left shift by k 30-bit units (ie. by 30*k bits) */
void mpclshift (mp a, u32 k, mp b)
{
        register u32 *aa = a;
        register u32 *bb = b;
        register u32 kk = k;
        u32 sa = *a;
        register u32 sb = sa+kk;

        if (iszero(aa)) return;

        /* set new length */
        *bb = sb;

        /* shift the remaining chunks */
        for (aa+=sa, bb+=sb; sb>0; sb--, aa--, bb--)
                *bb = (sb>kk)? *aa : 0L;

        return;
}