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
Gsm_Coder(struct gsm_state * State,int16_t * s,int16_t * LARc,int16_t * Nc,int16_t * bc,int16_t * Mc,int16_t * xmaxc,int16_t * xMc)17 void 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