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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 /* $Header: /tmp_amd/presto/export/kbs/jutta/src/gsm/RCS/code.c,v 1.3 1996/07/02 09:59:05 jutta Exp $ */
8 
9 #include	"config.h"
10 
11 
12 #ifdef	HAS_STRING_H
13 #include	<string.h>
14 #else
15 #	include "proto.h"
16 	extern char	* memcpy P((char *, char *, int));
17 #endif
18 
19 #include	"private.h"
20 #include	"gsm.h"
21 #include	"proto.h"
22 
23 /*
24  *  4.2 FIXED POINT IMPLEMENTATION OF THE RPE-LTP CODER
25  */
26 
27 void Gsm_Coder P8((S,s,LARc,Nc,bc,Mc,xmaxc,xMc),
28 
29 	struct gsm_state	* S,
30 
31 	word	* s,	/* [0..159] samples		  	IN	*/
32 
33 /*
34  * The RPE-LTD coder works on a frame by frame basis.  The length of
35  * the frame is equal to 160 samples.  Some computations are done
36  * once per frame to produce at the output of the coder the
37  * LARc[1..8] parameters which are the coded LAR coefficients and
38  * also to realize the inverse filtering operation for the entire
39  * frame (160 samples of signal d[0..159]).  These parts produce at
40  * the output of the coder:
41  */
42 
43 	word	* LARc,	/* [0..7] LAR coefficients		OUT	*/
44 
45 /*
46  * Procedure 4.2.11 to 4.2.18 are to be executed four times per
47  * frame.  That means once for each sub-segment RPE-LTP analysis of
48  * 40 samples.  These parts produce at the output of the coder:
49  */
50 
51 	word	* Nc,	/* [0..3] LTP lag			OUT 	*/
52 	word	* bc,	/* [0..3] coded LTP gain		OUT 	*/
53 	word	* Mc,	/* [0..3] RPE grid selection		OUT     */
54 	word	* xmaxc,/* [0..3] Coded maximum amplitude	OUT	*/
55 	word	* xMc	/* [13*4] normalized RPE samples	OUT	*/
56 )
57 {
58 	int	k;
59 	word	* dp  = S->dp0 + 120;	/* [ -120...-1 ] */
60 	word	* dpp = dp;		/* [ 0...39 ]	 */
61 
62 	word	so[160];
63 
64 	Gsm_Preprocess			(S, s, so);
65 	Gsm_LPC_Analysis		(S, so, LARc);
66 	Gsm_Short_Term_Analysis_Filter	(S, LARc, so);
67 
68 	for (k = 0; k <= 3; k++, xMc += 13) {
69 
70 		Gsm_Long_Term_Predictor	( S,
71 					 so+k*40, /* d      [0..39] IN	*/
72 					 dp,	  /* dp  [-120..-1] IN	*/
73 					S->e + 5, /* e      [0..39] OUT	*/
74 					dpp,	  /* dpp    [0..39] OUT */
75 					 Nc++,
76 					 bc++);
77 
78 		Gsm_RPE_Encoding	( S,
79 					S->e + 5,/* e	  ][0..39][ IN/OUT */
80 					  xmaxc++, Mc++, xMc );
81 		/*
82 		 * Gsm_Update_of_reconstructed_short_time_residual_signal
83 		 *			( dpp, S->e + 5, dp );
84 		 */
85 
86 		{ register int i;
87 		  register longword ltmp;
88 		  for (i = 0; i <= 39; i++)
89 			dp[ i ] = GSM_ADD( S->e[5 + i], dpp[i] );
90 		}
91 		dp  += 40;
92 		dpp += 40;
93 
94 	}
95 	(void)memcpy( (char *)S->dp0, (char *)(S->dp0 + 160),
96 		120 * sizeof(*S->dp0) );
97 }
98