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+/* ------------------------------------------------------------------
+ * Copyright (C) 1998-2009 PacketVideo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ * -------------------------------------------------------------------
+ */
+/*
+
+ Pathname: getmask.c
+
+------------------------------------------------------------------------------
+ REVISION HISTORY
+
+ Description: Modified from original shareware code
+
+ Description: Modified to pass variables by reference to eliminate use
+ of global variables.
+ Replaced for-loop style memory initialization with memset()
+
+ Description: (1) Modified to bring code in-line with PV standard
+ (2) Removed multiple returns, Replaced multiple 'if's with
+ switch
+
+ Description: (1) Modified per review comments
+ (2) increment pointer pMask after memset
+
+ Description: Make the maximum number of bits requested from getbits
+ become a constant.
+
+ Description: Typecast 1 to UInt32 for bitmask to avoid masking on a 16-bit
+ platform
+
+ Description: Replace some instances of getbits to get9_n_lessbits
+ when the number of bits read is 9 or less.
+
+ Who: Date: MM/DD/YYYY
+ Description:
+
+------------------------------------------------------------------------------
+ INPUT AND OUTPUT DEFINITIONS
+
+ Inputs:
+ pFrameInfo = pointer to structure that holds information for current
+ frame, Type FrameInfo
+
+ pInputStream= pointer to structure that holds input stream information
+ Type BITS
+
+ pGroup = pointer to array that holds the stop window index for
+ each group in current frame, Type Int
+
+ max_sfb = number of active sfbs for each window, Type Int
+
+ mask[] = array that holds the MS_mask information
+ Type Int
+
+ Local Stores/Buffers/Pointers Needed:
+ None
+
+ Global Stores/Buffers/Pointers Needed:
+ None
+
+ Outputs:
+ mask_present = 0 (no Mid/Side mixed)
+ 2 (Mid/Side mixed present for entire frame)
+ 1 (Mid/Side mixed information read from bitstream)
+ -1 (invalid mask_present read from bitstream)
+
+ Pointers and Buffers Modified:
+ pMask contents replaced by MS information of each scalefactor band
+
+ Local Stores Modified:
+ None
+
+ Global Stores Modified:
+ None
+
+------------------------------------------------------------------------------
+ FUNCTION DESCRIPTION
+
+ This function reads the Mid/Side(MS) mask information from the input
+ bitstream. If the mask_present field is equal to 2, the mask bits is set to
+ 1 for the entire frame. If mask_present has a value of 0, the function
+ returns 0, If mask_present is set to 1, the Mid/Side(MS) information is
+ read from the input stream. When mask_present is 3, an error code (-1) is
+ generated.
+ The Mid/Side(MS) information is later used for mixing the left and right
+ channel sounds. Each scalefactor band has its own MS information.
+
+ (ISO comments: read a synthesis mask, read a synthesis mask uses
+ EXTENDED_MS_MASK and grouped mask )
+
+------------------------------------------------------------------------------
+ REQUIREMENTS
+
+ This function shall replace the contents of pMask with the MS information
+ of each scalefactor band
+
+------------------------------------------------------------------------------
+ REFERENCES
+
+ (1) MPEG-2 NBC Audio Decoder
+ "This software module was originally developed by AT&T, Dolby
+ Laboratories, Fraunhofer Gesellschaft IIS in the course of development
+ of the MPEG-2 NBC/MPEG-4 Audio standard ISO/IEC 13818-7, 14496-1,2 and
+ 3. This software module is an implementation of a part of one or more
+ MPEG-2 NBC/MPEG-4 Audio tools as specified by the MPEG-2 NBC/MPEG-4
+ Audio standard. ISO/IEC gives users of the MPEG-2 NBC/MPEG-4 Audio
+ standards free license to this software module or modifications thereof
+ for use in hardware or software products claiming conformance to the
+ MPEG-2 NBC/MPEG-4 Audio standards. Those intending to use this software
+ module in hardware or software products are advised that this use may
+ infringe existing patents. The original developer of this software
+ module and his/her company, the subsequent editors and their companies,
+ and ISO/IEC have no liability for use of this software module or
+ modifications thereof in an implementation. Copyright is not released
+ for non MPEG-2 NBC/MPEG-4 Audio conforming products.The original
+ developer retains full right to use the code for his/her own purpose,
+ assign or donate the code to a third party and to inhibit third party
+ from using the code for non MPEG-2 NBC/MPEG-4 Audio conforming products.
+ This copyright notice must be included in all copies or derivative
+ works."
+ Copyright(c)1996.
+
+ (2) ISO/IEC 14496-3: 1999(E)
+ Subpart 4
+ p15 (Table 4.4.5 getmask)
+
+------------------------------------------------------------------------------
+ PSEUDO-CODE
+
+ CALL getbits(LEN_MASK_PRES, pInputStream)
+ MODIFYING (pInputStream)
+ RETURNING (mask present information)
+ mask_present = mask present information
+
+ SWITCH (mask_present)
+
+ CASE (0):
+ BREAK;
+
+ CASE (2):
+ nwin = pFrameInfo->num_win;
+ FOR(win = 0; win < nwin; win = *(pGroup++))
+
+ FOR(sfb = pFrameInfo->sfb_per_win[win]; sfb > 0; sfb--)
+ *(pMask++) = 1;
+ ENDFOR
+
+ ENDFOR
+
+ BREAK;
+
+ CASE(1):
+
+ nwin = pFrameInfo->num_win;
+
+ nToDo = max_sfb;
+
+ WHILE (nToDo > 0)
+ nCall = nToDo;
+
+ IF (nCall > MAX_GETBITS)
+ THEN
+ nCall = MAX_GETBITS;
+ ENDIF
+
+ tempMask =
+ getbits(
+ nCall,
+ pInputStream);
+
+ bitmask = 1 << (nCall - 1);
+ FOR (sfb = nCall; sfb > 0; sfb--)
+ *(pMask++) = (tempMask & bitmask) >> (sfb - 1);
+ bitmask >>= 1;
+ ENDFOR
+
+ nToDo -= nCall;
+ END WHILE
+
+ pv_memset(
+ pMask,
+ 0,
+ (pFrameInfo->sfb_per_win[win]-max_sfb)*sizeof(*pMask));
+
+ ENDFOR (win)
+
+ BREAK
+
+ DEFAULT:
+ mask_present = -1
+
+ ENDSWITCH
+
+ RETURN mask_present
+
+------------------------------------------------------------------------------
+*/
+
+
+/*----------------------------------------------------------------------------
+; INCLUDES
+----------------------------------------------------------------------------*/
+#include "pv_audio_type_defs.h"
+#include "huffman.h"
+#include "aac_mem_funcs.h"
+#include "e_maskstatus.h"
+
+/*----------------------------------------------------------------------------
+; MACROS
+; Define module specific macros here
+----------------------------------------------------------------------------*/
+
+/*----------------------------------------------------------------------------
+; DEFINES
+; Include all pre-processor statements here. Include conditional
+; compile variables also.
+----------------------------------------------------------------------------*/
+
+/*----------------------------------------------------------------------------
+; LOCAL FUNCTION DEFINITIONS
+; Function Prototype declaration
+----------------------------------------------------------------------------*/
+
+/*----------------------------------------------------------------------------
+; LOCAL STORE/BUFFER/POINTER DEFINITIONS
+; Variable declaration - defined here and used outside this module
+----------------------------------------------------------------------------*/
+
+/*----------------------------------------------------------------------------
+; EXTERNAL FUNCTION REFERENCES
+; Declare functions defined elsewhere and referenced in this module
+----------------------------------------------------------------------------*/
+
+/*----------------------------------------------------------------------------
+; EXTERNAL GLOBAL STORE/BUFFER/POINTER REFERENCES
+; Declare variables used in this module but defined elsewhere
+----------------------------------------------------------------------------*/
+
+/*----------------------------------------------------------------------------
+; FUNCTION CODE
+----------------------------------------------------------------------------*/
+Int getmask(
+ FrameInfo *pFrameInfo,
+ BITS *pInputStream,
+ Int group[],
+ Int max_sfb,
+ Int mask[])
+{
+
+ Int win; /* window index */
+ Int sfb;
+ Int mask_present;
+ Int *pMask;
+ Int *pGroup;
+ Int nwin;
+ Int nCall;
+ Int nToDo;
+ UInt32 tempMask;
+ UInt32 bitmask;
+
+ pMask = mask;
+ pGroup = group;
+
+ mask_present =
+ get9_n_lessbits(
+ LEN_MASK_PRES,
+ pInputStream);
+
+ switch (mask_present)
+ {
+ case(MASK_NOT_PRESENT):
+ /* special EXTENDED_MS_MASK cases */
+ /* no ms at all */
+ break;
+
+ case(MASK_ALL_FRAME):
+ /* MS for whole spectrum on, mask bits set to 1 */
+ nwin = pFrameInfo->num_win;
+ for (win = 0; win < nwin; win = *(pGroup++))
+ {
+ for (sfb = pFrameInfo->sfb_per_win[win]; sfb > 0; sfb--)
+ {
+ *(pMask++) = 1; /* cannot use memset for Int type */
+ }
+
+ }
+
+ break;
+
+ case(MASK_FROM_BITSTREAM):
+ /* MS_mask_present==1, get mask information*/
+ nwin = pFrameInfo->num_win;
+ for (win = 0; win < nwin; win = *(pGroup++))
+ {
+ /*
+ * the following code is equivalent to
+ *
+ * for(sfb = max_sfb; sfb > 0; sfb--)
+ * {
+ * *(pMask++) =
+ * getbits(
+ * LEN_MASK,
+ * pInputStream);
+ * }
+ *
+ * in order to save the calls to getbits, the above
+ * for-loop is broken into two parts
+ */
+
+ nToDo = max_sfb;
+
+ while (nToDo > 0)
+ {
+ nCall = nToDo;
+
+ if (nCall > MAX_GETBITS)
+ {
+ nCall = MAX_GETBITS;
+ }
+
+ tempMask =
+ getbits(
+ nCall,
+ pInputStream);
+
+ bitmask = (UInt32) 1 << (nCall - 1);
+ for (sfb = nCall; sfb > 0; sfb--)
+ {
+ *(pMask++) = (Int)((tempMask & bitmask) >> (sfb - 1));
+ bitmask >>= 1;
+ }
+
+ nToDo -= nCall;
+ }
+
+ /*
+ * set remaining sfbs to zero
+ * re-use nCall to save one variable on stack
+ */
+
+ nCall = pFrameInfo->sfb_per_win[win] - max_sfb;
+
+
+ if (nCall >= 0)
+ {
+ pv_memset(pMask,
+ 0,
+ nCall*sizeof(*pMask));
+
+ pMask += nCall;
+ }
+ else
+ {
+ mask_present = MASK_ERROR;
+ break;
+ }
+
+
+ } /* for (win) */
+
+ break;
+
+ default:
+ /* error */
+ break;
+
+ } /* switch (mask_present) */
+
+ return mask_present;
+
+} /* getmask */
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