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comparison libtwamr/lsp_lsf.c @ 344:05a46720af0f

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libtwamr: integrate d_plsf_3.c
author Mychaela Falconia <falcon@freecalypso.org>
date Fri, 19 Apr 2024 01:23:15 +0000
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343:3f574255c3aa 344:05a46720af0f
1 /*
2 ********************************************************************************
3 *
4 * GSM AMR-NB speech codec R98 Version 7.6.0 December 12, 2001
5 * R99 Version 3.3.0
6 * REL-4 Version 4.1.0
7 *
8 ********************************************************************************
9 *
10 * File : lsp_lsf.c
11 * Purpose : Lsp_lsf: Transformation lsp to lsf
12 * : Lsf_lsp: Transformation lsf to lsp
13 *
14 ********************************************************************************
15 */
16 /*
17 ********************************************************************************
18 * MODULE INCLUDE FILE AND VERSION ID
19 ********************************************************************************
20 */
21 #include "namespace.h"
22 #include "lsp_lsf.h"
23
24 /*
25 ********************************************************************************
26 * INCLUDE FILES
27 ********************************************************************************
28 */
29 #include "typedef.h"
30 #include "basic_op.h"
31 #include "no_count.h"
32
33 /*
34 ********************************************************************************
35 * LOCAL VARIABLES AND TABLES
36 ********************************************************************************
37 */
38 #include "lsp_lsf.tab" /* Look-up table for transformations */
39
40 /*
41 ********************************************************************************
42 * PUBLIC PROGRAM CODE
43 ********************************************************************************
44 */
45 /*************************************************************************
46 *
47 * FUNCTIONS: Lsp_lsf and Lsf_lsp
48 *
49 * PURPOSE:
50 * Lsp_lsf: Transformation lsp to lsf
51 * Lsf_lsp: Transformation lsf to lsp
52 *
53 * DESCRIPTION:
54 * lsp[i] = cos(2*pi*lsf[i]) and lsf[i] = arccos(lsp[i])/(2*pi)
55 *
56 * The transformation from lsp[i] to lsf[i] and lsf[i] to lsp[i] are
57 * approximated by a look-up table and interpolation.
58 *
59 *************************************************************************/
60 void Lsf_lsp (
61 Word16 lsf[], /* (i) : lsf[m] normalized (range: 0.0<=val<=0.5) */
62 Word16 lsp[], /* (o) : lsp[m] (range: -1<=val<1) */
63 Word16 m /* (i) : LPC order */
64 )
65 {
66 Word16 i, ind, offset;
67 Word32 L_tmp;
68
69 for (i = 0; i < m; i++)
70 {
71 ind = shr (lsf[i], 8); /* ind = b8-b15 of lsf[i] */
72 offset = lsf[i] & 0x00ff; logic16 (); /* offset = b0-b7 of lsf[i] */
73
74 /* lsp[i] = table[ind]+ ((table[ind+1]-table[ind])*offset) / 256 */
75
76 L_tmp = L_mult (sub (table[ind + 1], table[ind]), offset);
77 lsp[i] = add (table[ind], extract_l (L_shr (L_tmp, 9)));
78 move16 ();
79 }
80 return;
81 }
82
83 void Lsp_lsf (
84 Word16 lsp[], /* (i) : lsp[m] (range: -1<=val<1) */
85 Word16 lsf[], /* (o) : lsf[m] normalized (range: 0.0<=val<=0.5) */
86 Word16 m /* (i) : LPC order */
87 )
88 {
89 Word16 i, ind;
90 Word32 L_tmp;
91
92 ind = 63; move16 (); /* begin at end of table -1 */
93
94 for (i = m - 1; i >= 0; i--)
95 {
96 /* find value in table that is just greater than lsp[i] */
97 test ();
98 while (sub (table[ind], lsp[i]) < 0)
99 {
100 ind--;
101 test ();
102 }
103
104 /* acos(lsp[i])= ind*256 + ( ( lsp[i]-table[ind] ) *
105 slope[ind] )/4096 */
106
107 L_tmp = L_mult (sub (lsp[i], table[ind]), slope[ind]);
108 /*(lsp[i]-table[ind])*slope[ind])>>12*/
109 lsf[i] = round (L_shl (L_tmp, 3)); move16 ();
110 lsf[i] = add (lsf[i], shl (ind, 8)); move16 ();
111 }
112 return;
113 }