source: svn/trunk/newcon3bcm2_21bu/magnum/portinginterface/ads/7552/bads_mth.c

/***************************************************************************
 *     (c)2003-2010 Broadcom Corporation
 *  
 *  This program is the proprietary software of Broadcom Corporation and/or its licensors,
 *  and may only be used, duplicated, modified or distributed pursuant to the terms and
 *  conditions of a separate, written license agreement executed between you and Broadcom
 *  (an "Authorized License").  Except as set forth in an Authorized License, Broadcom grants
 *  no license (express or implied), right to use, or waiver of any kind with respect to the
 *  Software, and Broadcom expressly reserves all rights in and to the Software and all
 *  intellectual property rights therein.  IF YOU HAVE NO AUTHORIZED LICENSE, THEN YOU
 *  HAVE NO RIGHT TO USE THIS SOFTWARE IN ANY WAY, AND SHOULD IMMEDIATELY
 *  NOTIFY BROADCOM AND DISCONTINUE ALL USE OF THE SOFTWARE.  
 *   
 *  Except as expressly set forth in the Authorized License,
 *   
 *  1.     This program, including its structure, sequence and organization, constitutes the valuable trade
 *  secrets of Broadcom, and you shall use all reasonable efforts to protect the confidentiality thereof,
 *  and to use this information only in connection with your use of Broadcom integrated circuit products.
 *   
 *  2.     TO THE MAXIMUM EXTENT PERMITTED BY LAW, THE SOFTWARE IS PROVIDED "AS IS" 
 *  AND WITH ALL FAULTS AND BROADCOM MAKES NO PROMISES, REPRESENTATIONS OR 
 *  WARRANTIES, EITHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, WITH RESPECT TO 
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 * 
 * $brcm_Workfile: bads_mth.c $
 * $brcm_Revision: Hydra_Software_Devel/2 $
 * $brcm_Date: 12/20/11 6:06p $
 *
 * Module Description:
 *
 * Revision History:
 *
 ***************************************************************************/
#include "bstd.h"
#include "bmth.h"
#include "bmth_fix.h"


/***************************************************************************
* BADS_2560log10() This function calculated 256*10log10(x)
***************************************************************************/
uint32_t BMTH_2560log10(uint32_t x)
{
  int32_t  x1;
  int32_t  x2;
  int32_t  x3;
  int32_t  x4;

  if (x == 0)
    return 0;

  x1 = 31;
  while (!((x >> x1) & 1))
    x1 = x1-1;
  x1 = x1+1;

  if (x1 > 20)
    x2 = (int32_t)(x >> (x1 - 8));
  else
  x2 = (int32_t)((x << 8) >> x1);
   
  x3 = -24381739 + x2*(62348 + (x2 << 7));
  x4 = 5907991 + (x2 << 16);

  return (unsigned)((770*(x3/(x4 >> 8) + (x1 << 8))) >> 8);
}