1 files changed, 103 insertions, 0 deletions
diff --git a/libAACdec/src/aacdec_hcr_bit.cpp b/libAACdec/src/aacdec_hcr_bit.cpp
new file mode 100644
index 0000000..92695d9
--- /dev/null
+++ b/libAACdec/src/aacdec_hcr_bit.cpp
@@ -0,0 +1,103 @@
+/*****************************  MPEG-4 AAC Decoder  ***************************
+
+                      (C) Copyright Fraunhofer IIS 2000-2008
+                               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.
+
+
+   $Id$
+   Author(s):   Robert Weidner (DSP Solutions)
+   Description: HCR Decoder: Bitstream reading
+
+   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.
+
+*******************************************************************************/
+
+#include "aacdec_hcr_bit.h"
+
+
+/*---------------------------------------------------------------------------------------------
+        description:  This function toggles the read direction.
+-----------------------------------------------------------------------------------------------
+        input:        current read direction
+-----------------------------------------------------------------------------------------------
+        return:       new read direction
+-------------------------------------------------------------------------------------------- */
+UCHAR ToggleReadDirection(UCHAR readDirection)
+{
+  if ( readDirection == FROM_LEFT_TO_RIGHT ) {
+    return FROM_RIGHT_TO_LEFT;
+  }
+  else {
+    return FROM_LEFT_TO_RIGHT;
+  }
+}
+
+
+/*---------------------------------------------------------------------------------------------
+     description:   This function returns a bit from the bitstream according to read direction.
+                    It is called very often, therefore it makes sense to inline it (runtime).
+-----------------------------------------------------------------------------------------------
+        input:    - handle to FDK bitstream
+                  - reference value marking start of bitfield
+                  - pLeftStartOfSegment
+                  - pRightStartOfSegment
+                  - readDirection
+-----------------------------------------------------------------------------------------------
+        return:   - bit from bitstream
+-------------------------------------------------------------------------------------------- */
+UINT HcrGetABitFromBitstream(HANDLE_FDK_BITSTREAM  bs,
+                             USHORT               *pLeftStartOfSegment,
+                             USHORT               *pRightStartOfSegment,
+                             UCHAR                 readDirection)
+{
+  UINT   bit;
+  INT    readBitOffset;
+
+  if (readDirection == FROM_LEFT_TO_RIGHT) {
+    readBitOffset = *pLeftStartOfSegment-FDKgetBitCnt(bs);
+    if( readBitOffset ) {
+      FDKpushBiDirectional(bs, readBitOffset);
+    }
+
+    bit = FDKreadBits(bs, 1);
+
+    *pLeftStartOfSegment += 1;
+  }
+  else {
+    readBitOffset = *pRightStartOfSegment-FDKgetBitCnt(bs);
+    if( readBitOffset ) {
+      FDKpushBiDirectional(bs, readBitOffset);
+    }
+
+    /* to be replaced with a brother function of FDKreadBits() */
+    bit = FDKreadBits(bs, 1);
+    FDKpushBack(bs, 2);
+
+    *pRightStartOfSegment -= 1;
+  }
+
+
+#if ERROR_GENERATOR_BIT_STREAM_HCR
+  static int a;
+  if ((++a % MODULO_DIVISOR_HCR) == 0) {
+    bit = (bit == 0) ? 1 : 0;
+  }
+#endif
+
+  return (bit);
+}
+