/* ------------------------------------------------------------------ * 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. ****************************************************************************************/ /* ------------------------------------------------------------------------------ Filename: cor_h_x2.cpp ------------------------------------------------------------------------------ */ /*---------------------------------------------------------------------------- ; INCLUDES ----------------------------------------------------------------------------*/ #include "typedef.h" #include "cnst.h" #include "cor_h_x.h" #include "cor_h_x2.h" // BX #include "basic_op.h" #include "l_abs.h" /*---------------------------------------------------------------------------- ; MACROS ; Define module specific macros here ----------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------- ; DEFINES ; Include all pre-processor statements here. Include conditional ; compile variables also. ----------------------------------------------------------------------------*/ #define LOG2_OF_32 5 /*---------------------------------------------------------------------------- ; LOCAL FUNCTION DEFINITIONS ; Function Prototype declaration ----------------------------------------------------------------------------*/ /*---------------------------------------------------------------------------- ; LOCAL STORE/BUFFER/POINTER DEFINITIONS ; Variable declaration - defined here and used outside this module ----------------------------------------------------------------------------*/ /* ------------------------------------------------------------------------------ FUNCTION NAME: cor_h_x2 ------------------------------------------------------------------------------ INPUT AND OUTPUT DEFINITIONS Inputs: h = vector containing the impulse response of the weighted synthesis filter; vector contents are of type Word16; vector length is 2 * L_SUBFR x = target signal vector; vector contents are of type Word16; vector length is L_SUBFR dn = vector containing the correlation between the target and the impulse response; vector contents are of type Word16; vector length is L_CODE sf = scaling factor of type Word16 ; 2 when mode is MR122, 1 for all other modes nb_track = number of ACB tracks (Word16) step = step size between pulses in one track (Word16) pOverflow = pointer to overflow (Flag) Outputs: dn contents are the newly calculated correlation values pOverflow = 1 if the math functions called by cor_h_x2 result in overflow else zero. Returns: None Global Variables Used: None Local Variables Needed: None ------------------------------------------------------------------------------ FUNCTION DESCRIPTION This function computes the correlation between the target signal (x) and the impulse response (h). The correlation is given by: d[n] = sum_{i=n}^{L-1} x[i] h[i-n], where: n=0,...,L-1 d[n] is normalized such that the sum of 5 maxima of d[n] corresponding to each position track does not saturate. ------------------------------------------------------------------------------ REQUIREMENTS None ------------------------------------------------------------------------------ REFERENCES cor_h.c, UMTS GSM AMR speech codec, R99 - Version 3.2.0, March 2, 2001 ------------------------------------------------------------------------------ PSEUDO-CODE The original etsi reference code uses a global flag Overflow. However, in the actual implementation a pointer to a the overflow flag is passed in. void cor_h_x2 ( Word16 h[], // (i): impulse response of weighted synthesis filter Word16 x[], // (i): target Word16 dn[], // (o): correlation between target and h[] Word16 sf, // (i): scaling factor: 2 for 12.2, 1 for others Word16 nb_track,// (i): the number of ACB tracks Word16 step // (i): step size from one pulse position to the next in one track ) { Word16 i, j, k; Word32 s, y32[L_CODE], max, tot; // first keep the result on 32 bits and find absolute maximum tot = 5; for (k = 0; k < nb_track; k++) { max = 0; for (i = k; i < L_CODE; i += step) { s = 0; for (j = i; j < L_CODE; j++) s = L_mac (s, x[j], h[j - i]); y32[i] = s; s = L_abs (s); if (L_sub (s, max) > (Word32) 0L) max = s; } tot = L_add (tot, L_shr (max, 1)); } j = sub (norm_l (tot), sf); for (i = 0; i < L_CODE; i++) { dn[i] = pv_round (L_shl (y32[i], j)); } } ------------------------------------------------------------------------------ CAUTION [optional] [State any special notes, constraints or cautions for users of this function] ------------------------------------------------------------------------------ */ void cor_h_x2( Word16 h[], /* (i): impulse response of weighted synthesis filter */ Word16 x[], /* (i): target */ Word16 dn[], /* (o): correlation between target and h[] */ Word16 sf, /* (i): scaling factor: 2 for 12.2, 1 for others */ Word16 nb_track,/* (i): the number of ACB tracks */ Word16 step, /* (i): step size from one pulse position to the next in one track */ Flag *pOverflow ) { register Word16 i; register Word16 j; register Word16 k; Word32 s; Word32 y32[L_CODE]; Word32 max; Word32 tot; /* first keep the result on 32 bits and find absolute maximum */ tot = LOG2_OF_32; for (k = 0; k < nb_track; k++) { max = 0; for (i = k; i < L_CODE; i += step) { s = 0; for (j = i; j < L_CODE; j++) { s = amrnb_fxp_mac_16_by_16bb((Word32)x[j], (Word32)h[j-i], s); } s = s << 1; y32[i] = s; s = L_abs(s); if (s > max) { max = s; } } tot = (tot + (max >> 1)); } j = norm_l(tot) - sf; for (i = 0; i < L_CODE; i++) { dn[i] = pv_round(L_shl(y32[i], j, pOverflow), pOverflow); } return; }