1/* 2 * Copyright 1992 by Jutta Degener and Carsten Bormann, Technische 3 * Universitaet Berlin. See the accompanying file "COPYRIGHT" for 4 * details. THERE IS ABSOLUTELY NO WARRANTY FOR THIS SOFTWARE. 5 */ 6 7 8#include <stdlib.h> 9#include <string.h> 10 11#include "gsm610_priv.h" 12 13/* 14 * 4.2 FIXED POINT IMPLEMENTATION OF THE RPE-LTP CODER 15 */ 16 17void Gsm_Coder ( 18 19 struct gsm_state * State, 20 21 int16_t * s, /* [0..159] samples IN */ 22 23/* 24 * The RPE-LTD coder works on a frame by frame basis. The length of 25 * the frame is equal to 160 samples. Some computations are done 26 * once per frame to produce at the output of the coder the 27 * LARc [1..8] parameters which are the coded LAR coefficients and 28 * also to realize the inverse filtering operation for the entire 29 * frame (160 samples of signal d [0..159]). These parts produce at 30 * the output of the coder: 31 */ 32 33 int16_t * LARc, /* [0..7] LAR coefficients OUT */ 34 35/* 36 * Procedure 4.2.11 to 4.2.18 are to be executed four times per 37 * frame. That means once for each sub-segment RPE-LTP analysis of 38 * 40 samples. These parts produce at the output of the coder: 39 */ 40 41 int16_t *Nc, /* [0..3] LTP lag OUT */ 42 int16_t *bc, /* [0..3] coded LTP gain OUT */ 43 int16_t *Mc, /* [0..3] RPE grid selection OUT */ 44 int16_t *xmaxc, /* [0..3] Coded maximum amplitude OUT */ 45 int16_t *xMc /* [13*4] normalized RPE samples OUT */ 46) 47{ 48 int k ; 49 int16_t *dp = State->dp0 + 120 ; /* [-120...-1] */ 50 int16_t *dpp = dp ; /* [0...39] */ 51 52 int16_t so [160] ; 53 54 Gsm_Preprocess (State, s, so) ; 55 Gsm_LPC_Analysis (State, so, LARc) ; 56 Gsm_Short_Term_Analysis_Filter (State, LARc, so) ; 57 58 for (k = 0 ; k <= 3 ; k++, xMc += 13) 59 { Gsm_Long_Term_Predictor (State, 60 so+k*40, /* d [0..39] IN */ 61 dp, /* dp [-120..-1] IN */ 62 State->e + 5, /* e [0..39] OUT */ 63 dpp, /* dpp [0..39] OUT */ 64 Nc++, 65 bc++) ; 66 67 Gsm_RPE_Encoding (/*-S,-*/ 68 State->e + 5, /* e ][0..39][IN/OUT */ 69 xmaxc++, Mc++, xMc) ; 70 /* 71 * Gsm_Update_of_reconstructed_short_time_residual_signal 72 * (dpp, State->e + 5, dp) ; 73 */ 74 75 { 76 register int i ; 77 for (i = 0 ; i <= 39 ; i++) 78 dp [i] = GSM_ADD (State->e [5 + i], dpp [i]) ; 79 } 80 dp += 40 ; 81 dpp += 40 ; 82 83 } 84 memcpy ((char *) State->dp0, (char *) (State->dp0 + 160), 85 120 * sizeof (*State->dp0)) ; 86} 87 88