/* ------------------------------------------------------------------ * 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/cor_h_x.c Date: 09/07/2000 ------------------------------------------------------------------------------ REVISION HISTORY Description: Created a separate file for cor_h_x function. Description: Synchronized file with UMTS versin 3.2.0. Updated coding template. Description: Made the following changes per comments from Phase 2/3 review: 1. Modified FOR loop in the code to count down. 2. Fixed typecasting issue with TI C compiler. Description: Added call to round() and L_shl() functions in the last FOR loop to make code bit-exact. Updated copyright year. Description: Modified to pass pOverflow in via a pointer, rather than invoking it as a global variable. Description: Made the following changes 1. Unrolled the correlation loop and add mechanism control to compute odd or even number of computations. 2. Use pointer to avoid continuos addresses calculation 2. Eliminated math operations that check for saturation. Description: Changed round function name to pv_round to avoid conflict with round function in C standard library. Description: ------------------------------------------------------------------------------ */ /*---------------------------------------------------------------------------- ; INCLUDES ----------------------------------------------------------------------------*/ #include "typedef.h" #include "cnst.h" #include "cor_h_x.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 NAME: cor_h_x ------------------------------------------------------------------------------ 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 Outputs: dn contents are the newly calculated correlation values pOverflow = pointer of type Flag * to overflow indicator. 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 void cor_h_x ( 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 ) { cor_h_x2(h, x, dn, sf, NB_TRACK, STEP); } 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)); } } ------------------------------------------------------------------------------ RESOURCES USED [optional] When the code is written for a specific target processor the the resources used should be documented below. HEAP MEMORY USED: x bytes STACK MEMORY USED: x bytes CLOCK CYCLES: (cycle count equation for this function) + (variable used to represent cycle count for each subroutine called) where: (cycle count variable) = cycle count for [subroutine name] ------------------------------------------------------------------------------ CAUTION [optional] [State any special notes, constraints or cautions for users of this function] ------------------------------------------------------------------------------ */ void cor_h_x( 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 */ Flag *pOverflow /* (o): pointer to overflow flag */ ) { Word16 i; Word16 j; Word16 k; Word32 s; Word32 y32[L_CODE]; Word32 max; Word32 tot; Word16 *p_x; Word16 *p_ptr; Word32 *p_y32; tot = 5; for (k = 0; k < NB_TRACK; k++) /* NB_TRACK = 5 */ { max = 0; for (i = k; i < L_CODE; i += STEP) /* L_CODE = 40; STEP = 5 */ { s = 0; p_x = &x[i]; p_ptr = h; for (j = (L_CODE - i - 1) >> 1; j != 0; j--) { s += ((Word32) * (p_x++) * *(p_ptr++)) << 1; s += ((Word32) * (p_x++) * *(p_ptr++)) << 1; } s += ((Word32) * (p_x++) * *(p_ptr++)) << 1; if (!((L_CODE - i) & 1)) /* if even number of iterations */ { s += ((Word32) * (p_x++) * *(p_ptr++)) << 1; } y32[i] = s; if (s < 0) { s = -s; } if (s > max) { max = s; } } tot += (max >> 1); } j = norm_l(tot) - sf; p_ptr = dn; p_y32 = y32;; for (i = L_CODE >> 1; i != 0; i--) { s = L_shl(*(p_y32++), j, pOverflow); *(p_ptr++) = (s + 0x00008000) >> 16; s = L_shl(*(p_y32++), j, pOverflow); *(p_ptr++) = (s + 0x00008000) >> 16; } return; }