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      1 
      2 /* -----------------------------------------------------------------------------------------------------------
      3 Software License for The Fraunhofer FDK AAC Codec Library for Android
      4 
      5  Copyright  1995 - 2012 Fraunhofer-Gesellschaft zur Frderung der angewandten Forschung e.V.
      6   All rights reserved.
      7 
      8  1.    INTRODUCTION
      9 The Fraunhofer FDK AAC Codec Library for Android ("FDK AAC Codec") is software that implements
     10 the MPEG Advanced Audio Coding ("AAC") encoding and decoding scheme for digital audio.
     11 This FDK AAC Codec software is intended to be used on a wide variety of Android devices.
     12 
     13 AAC's HE-AAC and HE-AAC v2 versions are regarded as today's most efficient general perceptual
     14 audio codecs. AAC-ELD is considered the best-performing full-bandwidth communications codec by
     15 independent studies and is widely deployed. AAC has been standardized by ISO and IEC as part
     16 of the MPEG specifications.
     17 
     18 Patent licenses for necessary patent claims for the FDK AAC Codec (including those of Fraunhofer)
     19 may be obtained through Via Licensing (www.vialicensing.com) or through the respective patent owners
     20 individually for the purpose of encoding or decoding bit streams in products that are compliant with
     21 the ISO/IEC MPEG audio standards. Please note that most manufacturers of Android devices already license
     22 these patent claims through Via Licensing or directly from the patent owners, and therefore FDK AAC Codec
     23 software may already be covered under those patent licenses when it is used for those licensed purposes only.
     24 
     25 Commercially-licensed AAC software libraries, including floating-point versions with enhanced sound quality,
     26 are also available from Fraunhofer. Users are encouraged to check the Fraunhofer website for additional
     27 applications information and documentation.
     28 
     29 2.    COPYRIGHT LICENSE
     30 
     31 Redistribution and use in source and binary forms, with or without modification, are permitted without
     32 payment of copyright license fees provided that you satisfy the following conditions:
     33 
     34 You must retain the complete text of this software license in redistributions of the FDK AAC Codec or
     35 your modifications thereto in source code form.
     36 
     37 You must retain the complete text of this software license in the documentation and/or other materials
     38 provided with redistributions of the FDK AAC Codec or your modifications thereto in binary form.
     39 You must make available free of charge copies of the complete source code of the FDK AAC Codec and your
     40 modifications thereto to recipients of copies in binary form.
     41 
     42 The name of Fraunhofer may not be used to endorse or promote products derived from this library without
     43 prior written permission.
     44 
     45 You may not charge copyright license fees for anyone to use, copy or distribute the FDK AAC Codec
     46 software or your modifications thereto.
     47 
     48 Your modified versions of the FDK AAC Codec must carry prominent notices stating that you changed the software
     49 and the date of any change. For modified versions of the FDK AAC Codec, the term
     50 "Fraunhofer FDK AAC Codec Library for Android" must be replaced by the term
     51 "Third-Party Modified Version of the Fraunhofer FDK AAC Codec Library for Android."
     52 
     53 3.    NO PATENT LICENSE
     54 
     55 NO EXPRESS OR IMPLIED LICENSES TO ANY PATENT CLAIMS, including without limitation the patents of Fraunhofer,
     56 ARE GRANTED BY THIS SOFTWARE LICENSE. Fraunhofer provides no warranty of patent non-infringement with
     57 respect to this software.
     58 
     59 You may use this FDK AAC Codec software or modifications thereto only for purposes that are authorized
     60 by appropriate patent licenses.
     61 
     62 4.    DISCLAIMER
     63 
     64 This FDK AAC Codec software is provided by Fraunhofer on behalf of the copyright holders and contributors
     65 "AS IS" and WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, including but not limited to the implied warranties
     66 of merchantability and fitness for a particular purpose. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
     67 CONTRIBUTORS BE LIABLE for any direct, indirect, incidental, special, exemplary, or consequential damages,
     68 including but not limited to procurement of substitute goods or services; loss of use, data, or profits,
     69 or business interruption, however caused and on any theory of liability, whether in contract, strict
     70 liability, or tort (including negligence), arising in any way out of the use of this software, even if
     71 advised of the possibility of such damage.
     72 
     73 5.    CONTACT INFORMATION
     74 
     75 Fraunhofer Institute for Integrated Circuits IIS
     76 Attention: Audio and Multimedia Departments - FDK AAC LL
     77 Am Wolfsmantel 33
     78 91058 Erlangen, Germany
     79 
     80 www.iis.fraunhofer.de/amm
     81 amm-info (at) iis.fraunhofer.de
     82 ----------------------------------------------------------------------------------------------------------- */
     83 
     84 /*!
     85   \file
     86   \brief  CRC check coutines
     87 */
     88 
     89 #include "sbr_crc.h"
     90 
     91 #include "FDK_bitstream.h"
     92 #include "transcendent.h"
     93 
     94 #define MAXCRCSTEP    16
     95 #define MAXCRCSTEP_LD  4
     96 
     97 /*!
     98   \brief     crc calculation
     99 */
    100 static ULONG
    101 calcCRC (HANDLE_CRC hCrcBuf, ULONG bValue, int nBits)
    102 {
    103   int i;
    104   ULONG bMask = (1UL << (nBits - 1));
    105 
    106   for (i = 0; i < nBits; i++, bMask >>= 1) {
    107     USHORT flag = (hCrcBuf->crcState & hCrcBuf->crcMask) ? 1 : 0;
    108     USHORT flag1 = (bMask & bValue) ? 1 : 0;
    109 
    110     flag ^= flag1;
    111     hCrcBuf->crcState <<= 1;
    112     if (flag)
    113       hCrcBuf->crcState ^= hCrcBuf->crcPoly;
    114   }
    115 
    116   return (hCrcBuf->crcState);
    117 }
    118 
    119 
    120 /*!
    121   \brief     crc
    122 */
    123 static int
    124 getCrc (HANDLE_FDK_BITSTREAM hBs, ULONG NrBits)
    125 {
    126   int i;
    127   CRC_BUFFER CrcBuf;
    128 
    129   CrcBuf.crcState = SBR_CRC_START;
    130   CrcBuf.crcPoly  = SBR_CRC_POLY;
    131   CrcBuf.crcMask  = SBR_CRC_MASK;
    132 
    133   int CrcStep = NrBits>>MAXCRCSTEP_LD;
    134 
    135   int CrcNrBitsRest = (NrBits - CrcStep * MAXCRCSTEP);
    136   ULONG bValue;
    137 
    138   for (i = 0; i < CrcStep; i++) {
    139     bValue = FDKreadBits (hBs, MAXCRCSTEP);
    140     calcCRC (&CrcBuf, bValue, MAXCRCSTEP);
    141   }
    142 
    143   bValue = FDKreadBits (hBs, CrcNrBitsRest);
    144   calcCRC (&CrcBuf, bValue, CrcNrBitsRest);
    145 
    146   return (CrcBuf.crcState & SBR_CRC_RANGE);
    147 
    148 }
    149 
    150 
    151 /*!
    152   \brief   crc interface
    153   \return  1: CRC OK, 0: CRC check failure
    154 */
    155 int
    156 SbrCrcCheck (HANDLE_FDK_BITSTREAM hBs, /*!< handle to bit-buffer  */
    157              LONG NrBits)              /*!< max. CRC length       */
    158 {
    159   int crcResult = 1;
    160   ULONG NrCrcBits;
    161   ULONG crcCheckResult;
    162   LONG NrBitsAvailable;
    163   ULONG crcCheckSum;
    164 
    165   crcCheckSum = FDKreadBits (hBs, 10);
    166 
    167   NrBitsAvailable = FDKgetValidBits(hBs);
    168   if (NrBitsAvailable <= 0){
    169     return 0;
    170   }
    171 
    172   NrCrcBits = fixMin ((INT)NrBits, (INT)NrBitsAvailable);
    173 
    174   crcCheckResult = getCrc (hBs, NrCrcBits);
    175   FDKpushBack(hBs, (NrBitsAvailable - FDKgetValidBits(hBs)) );
    176 
    177 
    178   if (crcCheckResult != crcCheckSum) {
    179     crcResult = 0;
    180   }
    181 
    182   return (crcResult);
    183 }
    184