/* ------------------------------------------------------------------ * 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. * ------------------------------------------------------------------- */ /**************************************************************************************** Portions of this file are derived from the following 3GPP standard: 3GPP TS 26.073 ANSI-C code for the Adaptive Multi-Rate (AMR) speech codec Available from http://www.3gpp.org (C) 2004, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TTA, TTC) Permission to distribute, modify and use this file under the standard license terms listed above has been obtained from the copyright holder. ****************************************************************************************/ /* ------------------------------------------------------------------------------ Pathname: ./audio/gsm-amr/c/src/dec_lag3.c Functions: Dec_lag3 Date: 01/31/2002 ------------------------------------------------------------------------------ REVISION HISTORY Description: (1) Updated to accept new parameter, Flag *pOverflow. (2) Placed file in the proper PV Software template. Description: (1) Removed "count.h" and "basic_op.h" and replaced with individual include files (add.h, sub.h, etc.) Description: (1) Removed optimization -- mult(i, 3, pOverflow) is NOT the same as adding i to itself 3 times. The reason is because the mult function does a right shift by 15, which will obliterate smaller numbers. Description: Replaced "int" and/or "char" with OSCL defined types. Description: ------------------------------------------------------------------------------ INPUT AND OUTPUT DEFINITIONS Inputs: index -- Word16 -- received pitch index t0_min -- Word16 -- minimum of search range t0_max -- Word16 -- maximum of search range i_subfr -- Word16 -- subframe flag T0_prev -- Word16 -- integer pitch delay of last subframe used in 2nd and 4th subframes flag4 -- Word16 -- flag for encoding with 4 bits Outputs: T0 -- Pointer to type Word16 -- integer part of pitch lag T0_frac -- Pointer to type Word16 -- fractional part of pitch lag pOverflow -- Pointer to type Flag -- Flag set when overflow occurs Returns: None. Global Variables Used: None Local Variables Needed: None ) ------------------------------------------------------------------------------ FUNCTION DESCRIPTION PURPOSE: Decoding of fractional pitch lag with 1/3 resolution. Extract the integer and fraction parts of the pitch lag from the received adaptive codebook index. See "Enc_lag3.c" for more details about the encoding procedure. The fractional lag in 1st and 3rd subframes is encoded with 8 bits while that in 2nd and 4th subframes is relatively encoded with 4, 5 and 6 bits depending on the mode. ------------------------------------------------------------------------------ REQUIREMENTS ------------------------------------------------------------------------------ REFERENCES dec_lag3.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 ------------------------------------------------------------------------------ PSEUDO-CODE ------------------------------------------------------------------------------ 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 "dec_lag3.h" #include "typedef.h" #include "basic_op.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 Dec_lag3(Word16 index, /* i : received pitch index */ Word16 t0_min, /* i : minimum of search range */ Word16 t0_max, /* i : maximum of search range */ Word16 i_subfr, /* i : subframe flag */ Word16 T0_prev, /* i : integer pitch delay of last subframe used in 2nd and 4th subframes */ Word16 * T0, /* o : integer part of pitch lag */ Word16 * T0_frac, /* o : fractional part of pitch lag */ Word16 flag4, /* i : flag for encoding with 4 bits */ Flag *pOverflow /* o : Flag set when overflow occurs */ ) { Word16 i; Word16 tmp_lag; if (i_subfr == 0) /* if 1st or 3rd subframe */ { if (index < 197) { tmp_lag = index + 2; tmp_lag = mult( tmp_lag, 10923, pOverflow); i = add( tmp_lag, 19, pOverflow); *T0 = i; /* i = 3 * (*T0) */ i = add(i, i, pOverflow); i = add(i, *T0, pOverflow); tmp_lag = sub( index, i, pOverflow); *T0_frac = add( tmp_lag, 58, pOverflow); } else { *T0 = index - 112; *T0_frac = 0; } } else { /* 2nd or 4th subframe */ if (flag4 == 0) { /* 'normal' decoding: either with 5 or 6 bit resolution */ i = add( index, 2, pOverflow); i = mult( i, 10923, pOverflow); i = sub( i, 1, pOverflow); *T0 = add( i, t0_min, pOverflow); /* i = 3* (*T0) */ i = add(add(i, i, pOverflow), i, pOverflow); tmp_lag = sub( index, 2, pOverflow); *T0_frac = sub( tmp_lag, i, pOverflow); } else { /* decoding with 4 bit resolution */ tmp_lag = T0_prev; i = sub( tmp_lag, t0_min, pOverflow); if (i > 5) { tmp_lag = add( t0_min, 5, pOverflow); } i = sub( t0_max, tmp_lag, pOverflow); if (i > 4) { tmp_lag = sub( t0_max, 4, pOverflow); } if (index < 4) { i = sub( tmp_lag, 5, pOverflow); *T0 = add( i, index, pOverflow); *T0_frac = 0; } else { /* 4 >= index < 12 */ if (index < 12) { i = index - 5; i = mult( i, 10923, pOverflow); i--; *T0 = add( i, tmp_lag, pOverflow); i = add( add( i, i, pOverflow), i, pOverflow); tmp_lag = index - 9; *T0_frac = sub( tmp_lag, i, pOverflow); } else { i = index - 12; i = add( i, tmp_lag, pOverflow); *T0 = add( i, 1, pOverflow); *T0_frac = 0; } } } /* end if (decoding with 4 bit resolution) */ } return; }