From 9bf37cc9712506b2483650c82d3c41152337ef7e Mon Sep 17 00:00:00 2001
From: Dave Burke <daveburke@google.com>
Date: Tue, 17 Apr 2012 09:51:45 -0700
Subject: Fraunhofer AAC codec.

License boilerplate update to follow.

Change-Id: I2810460c11a58b6d148d84673cc031f3685e79b5
---
 libSBRdec/src/sbr_crc.cpp | 125 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 libSBRdec/src/sbr_crc.cpp

(limited to 'libSBRdec/src/sbr_crc.cpp')

diff --git a/libSBRdec/src/sbr_crc.cpp b/libSBRdec/src/sbr_crc.cpp
new file mode 100644
index 0000000..3463710
--- /dev/null
+++ b/libSBRdec/src/sbr_crc.cpp
@@ -0,0 +1,125 @@
+/****************************************************************************
+
+                     (C) Copyright Fraunhofer IIS (2004)
+                               All Rights Reserved
+
+    Please be advised that this software and/or program delivery is
+    Confidential Information of Fraunhofer and subject to and covered by the
+
+    Fraunhofer IIS Software Evaluation Agreement
+    between Google Inc. and  Fraunhofer
+    effective and in full force since March 1, 2012.
+
+    You may use this software and/or program only under the terms and
+    conditions described in the above mentioned Fraunhofer IIS Software
+    Evaluation Agreement. Any other and/or further use requires a separate agreement.
+
+
+   This software and/or program is protected by copyright law and international
+   treaties. Any reproduction or distribution of this software and/or program,
+   or any portion of it, may result in severe civil and criminal penalties, and
+   will be prosecuted to the maximum extent possible under law.
+
+ $Id$
+
+*******************************************************************************/
+/*!
+  \file
+  \brief  CRC check coutines $Revision: 36841 $
+*/
+
+#include "sbr_crc.h"
+
+#include "FDK_bitstream.h"
+#include "transcendent.h"
+
+#define MAXCRCSTEP    16
+#define MAXCRCSTEP_LD  4
+
+/*!
+  \brief     crc calculation
+*/
+static ULONG
+calcCRC (HANDLE_CRC hCrcBuf, ULONG bValue, int nBits)
+{
+  int i;
+  ULONG bMask = (1UL << (nBits - 1));
+
+  for (i = 0; i < nBits; i++, bMask >>= 1) {
+    USHORT flag = (hCrcBuf->crcState & hCrcBuf->crcMask) ? 1 : 0;
+    USHORT flag1 = (bMask & bValue) ? 1 : 0;
+
+    flag ^= flag1;
+    hCrcBuf->crcState <<= 1;
+    if (flag)
+      hCrcBuf->crcState ^= hCrcBuf->crcPoly;
+  }
+
+  return (hCrcBuf->crcState);
+}
+
+
+/*!
+  \brief     crc
+*/
+static int
+getCrc (HANDLE_FDK_BITSTREAM hBs, ULONG NrBits)
+{
+  int i;
+  CRC_BUFFER CrcBuf;
+
+  CrcBuf.crcState = SBR_CRC_START;
+  CrcBuf.crcPoly  = SBR_CRC_POLY;
+  CrcBuf.crcMask  = SBR_CRC_MASK;
+
+  int CrcStep = NrBits>>MAXCRCSTEP_LD;
+
+  int CrcNrBitsRest = (NrBits - CrcStep * MAXCRCSTEP);
+  ULONG bValue;
+
+  for (i = 0; i < CrcStep; i++) {
+    bValue = FDKreadBits (hBs, MAXCRCSTEP);
+    calcCRC (&CrcBuf, bValue, MAXCRCSTEP);
+  }
+
+  bValue = FDKreadBits (hBs, CrcNrBitsRest);
+  calcCRC (&CrcBuf, bValue, CrcNrBitsRest);
+
+  return (CrcBuf.crcState & SBR_CRC_RANGE);
+
+}
+
+
+/*!
+  \brief   crc interface
+  \return  1: CRC OK, 0: CRC check failure
+*/
+int
+SbrCrcCheck (HANDLE_FDK_BITSTREAM hBs, /*!< handle to bit-buffer  */
+             LONG NrBits)              /*!< max. CRC length       */
+{
+  int crcResult = 1;
+  ULONG NrCrcBits;
+  ULONG crcCheckResult;
+  LONG NrBitsAvailable;
+  ULONG crcCheckSum;
+
+  crcCheckSum = FDKreadBits (hBs, 10);
+
+  NrBitsAvailable = FDKgetValidBits(hBs);
+  if (NrBitsAvailable <= 0){
+    return 0;
+  }
+
+  NrCrcBits = fixMin ((INT)NrBits, (INT)NrBitsAvailable);
+
+  crcCheckResult = getCrc (hBs, NrCrcBits);
+  FDKpushBack(hBs, (NrBitsAvailable - FDKgetValidBits(hBs)) );
+
+
+  if (crcCheckResult != crcCheckSum) {
+    crcResult = 0;
+  }
+
+  return (crcResult);
+}
-- 
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