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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: lt_decode.c
+
+
+------------------------------------------------------------------------------
+
+ REVISION HISTORY
+
+ Description: Modified from original shareware code
+
+ Description: Modified to pass variables by reference to eliminate use
+ of global variables.
+
+ Description: First round of optimizations.
+
+ Description: pInputStream is now the 2nd parameter to this function.
+
+ Description: Changed to work with MT's new get_ics_info.c function, which
+ only calls lt_decode if LTP is enabled. This removes one grab from the
+ bitstream and one "if" from this code. Also, changed setting of weight.
+ Now, rather than setting the actual weight, I only set the index into
+ a table in this function.
+
+ Description: Replace some instances of getbits to get9_n_lessbits
+ when the number of bits read is 9 or less and get1bits
+ when only 1 bit is read.
+
+ Who: Date:
+ Description:
+------------------------------------------------------------------------------
+ INPUT AND OUTPUT DEFINITIONS
+
+ Inputs:
+ win_type Type of window (SHORT or LONG)
+ [WINDOW_TYPE]
+
+ max_sfb Maximum number of active scalefactor bands
+ [Int]
+
+ pLt_pred Pointer to structure containing information for
+ long-term prediction.
+ [LT_PRED_STATUS *]
+
+ pInputStream Pointer to structure containing bitstream
+ information.
+ [BITS *]
+
+ Local Stores/Buffers/Pointers Needed:
+ None
+
+ Global Stores/Buffers/Pointers Needed:
+ None
+
+ Outputs:
+ None
+
+ Pointers and Buffers Modified:
+ pLt_pred->weight_index - updated with index into weight table for LTP.
+
+ Local Stores Modified:
+ None
+
+ Global Stores Modified:
+ None
+
+------------------------------------------------------------------------------
+ FUNCTION DESCRIPTION
+
+ This function decodes the bitstream elements for long term prediction
+
+------------------------------------------------------------------------------
+ REQUIREMENTS
+
+
+------------------------------------------------------------------------------
+ REFERENCES
+
+ (1) MPEG-2 NBC Audio Decoder
+ "This software module was originally developed by Nokia
+ in the course of development of the MPEG-2 AAC/MPEG-4 Audio standard
+ ISO/IEC13818-7, 14496-1, 2 and 3. This software module is an implementation
+ of a part of one or more MPEG-2 AAC/MPEG-4 Audio tools as specified by the
+ MPEG-2 aac/MPEG-4 Audio standard. ISO/IEC gives users of the
+ MPEG-2aac/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 aac/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, 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 aac/MPEG-4
+ Audio conforming products. The original developer retains full right to use
+ the code for the developer's own purpose, assign or donate the code to a
+ third party and to inhibit third party from using the code for non
+ MPEG-2 aac/MPEG-4 Audio conforming products. This copyright notice
+ must be included in all copies or derivative works."
+ Copyright (c)1997.
+
+------------------------------------------------------------------------------
+ PSEUDO-CODE
+
+ pDelay[0] = (Int) getbits(
+ LEN_LTP_LAG,
+ pInputStream);
+
+ temp_reg = (Int) getbits(
+ LEN_LTP_COEF,
+ pInputStream);
+
+ pLt_pred->weight = codebook[temp_reg];
+
+ last_band = max_sfb;
+
+ IF (win_type != EIGHT_SHORT_SEQUENCE)
+
+ IF (last_band > MAX_LT_PRED_LONG_SFB)
+
+ last_band = MAX_LT_PRED_LONG_SFB;
+
+ ENDIF
+
+ FOR (m = last_band; m > 0; m--)
+
+ *(pSfbPredictionUsed++) = (Int) getbits(
+ LEN_LTP_LONG_USED,
+ pInputStream);
+ ENDFOR
+
+ FOR (m = (max_sfb - last_band); m > 0; m--)
+
+ *(pSfbPredictionUsed++) = 0;
+
+ ENDFOR
+
+ ELSE
+
+ IF (last_band > MAX_LT_PRED_SHORT_SFB)
+
+ last_band = MAX_LT_PRED_SHORT_SFB;
+
+ ENDIF
+
+ prev_subblock = pDelay[0];
+
+ pWinPredictionUsed++;
+
+ pTempPtr = &pSfbPredictionUsed[0];
+
+ FOR (m = NUM_SHORT_WINDOWS; m > 0;)
+
+ m--;
+ temp_reg = (Int) getbits(
+ LEN_LTP_SHORT_USED,
+ pInputStream);
+
+ *(pWinPredictionUsed++) = temp_reg;
+
+ IF (temp_reg != FALSE)
+ {
+ *(pDelay++) = prev_subblock;
+
+ FOR (k = last_band; k > 0; k--)
+ {
+ *(pTempPtr++) = 1;
+ }
+ break;
+ ELSE
+ {
+ pDelay++;
+ pTempPtr += last_band;
+ }
+
+ ENDFOR (m = NUM_SHORT_WINDOWS; m > 0;)
+
+ prev_subblock += LTP_LAG_OFFSET;
+
+ FOR (; m > 0; m--)
+
+ temp_reg = (Int) getbits (
+ LEN_LTP_SHORT_USED,
+ pInputStream);
+
+ *(pWinPredictionUsed++) = temp_reg;
+
+ IF (temp_reg != FALSE)
+
+ temp_reg = (Int) getbits(
+ LEN_LTP_SHORT_LAG_PRESENT,
+ pInputStream);
+ IF (temp_reg != 0)
+
+ temp_reg = (Int) getbits(
+ LEN_LTP_SHORT_LAG,
+ pInputStream);
+
+ *(pDelay++) = prev_subblock - temp_reg;
+
+ ELSE
+
+ *(pDelay++) = prev_subblock - LTP_LAG_OFFSET;
+
+ ENDIF
+
+ FOR (k = last_band; k > 0; k--)
+ *(pTempPtr++) = 1;
+ ENDFOR
+
+ ELSE
+
+ pDelay++;
+ pTempPtr += last_band;
+
+ ENDIF
+
+ ENDFOR (; m > 0; m--)
+
+ ENDIF (win_type != EIGHT_SHORT_SEQUENCE)
+
+------------------------------------------------------------------------------
+ RESOURCES USED
+ When the code is written for a specific target processor the
+ the resources used should be documented below.
+
+ STACK USAGE: [stack count for this module] + [variable to represent
+ stack usage for each subroutine called]
+
+ where: [stack usage variable] = stack usage for [subroutine
+ name] (see [filename].ext)
+
+ DATA MEMORY USED: x words
+
+ PROGRAM MEMORY USED: x words
+
+ CLOCK CYCLES: [cycle count equation for this module] + [variable
+ used to represent cycle count for each subroutine
+ called]
+
+ where: [cycle count variable] = cycle count for [subroutine
+ name] (see [filename].ext)
+
+------------------------------------------------------------------------------
+*/
+
+/*----------------------------------------------------------------------------
+; INCLUDES
+----------------------------------------------------------------------------*/
+#include "pv_audio_type_defs.h"
+#include "lt_decode.h"
+#include "ltp_common_internal.h"
+#include "window_block_fxp.h"
+#include "e_window_sequence.h"
+#include "s_lt_pred_status.h"
+#include "s_bits.h"
+#include "ibstream.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
+----------------------------------------------------------------------------*/
+void lt_decode(
+ const WINDOW_SEQUENCE win_type,
+ BITS *pInputStream,
+ const Int max_sfb,
+ LT_PRED_STATUS *pLt_pred)
+{
+ Int wnd_num;
+ Int k;
+ Int last_band;
+ Int prev_subblock;
+ Int prev_subblock_nonzero;
+ Int temp_reg;
+
+ Bool *pWinPredictionUsed = pLt_pred->win_prediction_used;
+ Bool *pSfbPredictionUsed = pLt_pred->sfb_prediction_used;
+ Int *pTempPtr;
+ Int *pDelay = pLt_pred->delay;
+
+ pDelay[0] = (Int) get17_n_lessbits(
+ LEN_LTP_LAG, /* 11 bits */
+ pInputStream);
+
+ pLt_pred->weight_index = (Int) get9_n_lessbits(
+ LEN_LTP_COEF, /* 3 bits */
+ pInputStream);
+
+ last_band = max_sfb;
+
+ if (win_type != EIGHT_SHORT_SEQUENCE)
+ {
+
+ /* last_band = min(MAX_LT_PRED_LONG_SFB, max_sfb) MAX_SCFAC_BANDS */
+ if (last_band > MAX_LT_PRED_LONG_SFB)
+ {
+ last_band = MAX_LT_PRED_LONG_SFB;
+ }
+
+ for (k = last_band; k > 0; k--)
+ {
+ *(pSfbPredictionUsed++) = (Int) get1bits(pInputStream);
+ }
+
+ /*
+ * This is not a call to memset, because
+ * (max_sfb - last_band) should typically be a small value.
+ */
+ for (k = (max_sfb - last_band); k > 0; k--)
+ {
+ *(pSfbPredictionUsed++) = FALSE;
+ }
+ }
+ else /* (win_type == EIGHT_SHORT_SEQUENCE) */
+ {
+ /* last_band = min(MAX_LT_PRED_SHORT_SFB, max_sfb) */
+
+ if (last_band > MAX_LT_PRED_SHORT_SFB)
+ {
+ last_band = MAX_LT_PRED_SHORT_SFB;
+ }
+
+ /*
+ * The following two coding constructs are equivalent...
+ *
+ * first_time == 1
+ * for (wnd_num=NUM_SHORT_WINDOWS; wnd_num > 0; wnd_num--)
+ * {
+ * if (condition)
+ * {
+ * if (first_time == 1)
+ * {
+ * CODE SECTION A
+ * first_time = 0;
+ * }
+ * else
+ * {
+ * CODE SECTION B
+ * }
+ * }
+ * }
+ *
+ * -----------------------------------EQUIVALENT TO------------
+ *
+ * wnd_num=NUM_SHORT_WINDOWS;
+ *
+ * do
+ * {
+ * wnd_num--;
+ * if (condition)
+ * {
+ * CODE SECTION A
+ * break;
+ * }
+ * } while( wnd_num > 0)
+ *
+ * while (wnd_num > 0)
+ * {
+ * if (condition)
+ * {
+ * CODE SECTION B
+ * }
+ * wnd_num--;
+ * }
+ *
+ */
+
+ prev_subblock = pDelay[0];
+
+ pTempPtr = &pSfbPredictionUsed[0];
+
+ wnd_num = NUM_SHORT_WINDOWS;
+
+ prev_subblock_nonzero = prev_subblock;
+ prev_subblock += LTP_LAG_OFFSET;
+
+ do
+ {
+ /*
+ * Place decrement of wnd_num here, to insure
+ * that the decrement occurs before the
+ * break out of the do-while loop.
+ */
+ wnd_num--;
+
+ temp_reg = (Int) get1bits(pInputStream);
+
+ *(pWinPredictionUsed++) = temp_reg;
+
+ if (temp_reg != FALSE)
+ {
+ *(pDelay++) = prev_subblock_nonzero;
+
+ for (k = last_band; k > 0; k--)
+ {
+ *(pTempPtr++) = TRUE;
+ }
+ for (k = (max_sfb - last_band); k > 0; k--)
+ {
+ *(pTempPtr++) = FALSE;
+ }
+ break;
+
+ } /* if(pWinPredictionUsed) */
+ else
+ {
+ pDelay++;
+ pTempPtr += max_sfb;
+ }
+
+ }
+ while (wnd_num > 0);
+
+ /*
+ * This while loop picks up where the previous one left off.
+ * Notice that the code functions differently inside the loop
+ */
+
+ while (wnd_num > 0)
+ {
+ temp_reg = (Int) get1bits(pInputStream);
+
+ *(pWinPredictionUsed++) = temp_reg;
+
+ if (temp_reg != FALSE)
+ {
+ temp_reg = (Int) get1bits(pInputStream);
+ if (temp_reg != 0)
+ {
+ temp_reg = (Int) get9_n_lessbits(
+ LEN_LTP_SHORT_LAG,
+ pInputStream);
+
+ *(pDelay++) = prev_subblock - temp_reg;
+ }
+ else
+ {
+ *(pDelay++) = prev_subblock_nonzero;
+ }
+ for (k = last_band; k > 0; k--)
+ {
+ *(pTempPtr++) = TRUE;
+ }
+ for (k = (max_sfb - last_band); k > 0; k--)
+ {
+ *(pTempPtr++) = FALSE;
+ }
+
+ } /* if (temp_reg) */
+ else
+ {
+ pDelay++;
+ pTempPtr += max_sfb;
+ }
+
+ wnd_num--;
+
+ } /* while(wnd_num) */
+
+ } /* else (win_type == EIGHT_SHORT_SEQUENCE) */
+
+} /* lt_decode */
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