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comparison libtwamr/lsp_az.c @ 380:2ed325c9a507

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libtwamr: integrate lsp_az.c
author Mychaela Falconia <falcon@freecalypso.org>
date Mon, 06 May 2024 05:31:47 +0000
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379:176a44ff94a1 380:2ed325c9a507
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_az.c
11 * Purpose : Converts from the line spectral pairs (LSP) to
12 * : LP coefficients, for a 10th order filter.
13 * Description :
14 * - Find the coefficients of F1(z) and F2(z) (see Get_lsp_pol)
15 * - Multiply F1(z) by 1+z^{-1} and F2(z) by 1-z^{-1}
16 * - A(z) = ( F1(z) + F2(z) ) / 2
17 *
18 ********************************************************************************
19 */
20 /*
21 ********************************************************************************
22 * MODULE INCLUDE FILE AND VERSION ID
23 ********************************************************************************
24 */
25 #include "namespace.h"
26 #include "lsp_az.h"
27 /*
28 ********************************************************************************
29 * INCLUDE FILES
30 ********************************************************************************
31 */
32 #include "typedef.h"
33 #include "basic_op.h"
34 #include "oper_32b.h"
35 #include "no_count.h"
36
37 /*
38 ********************************************************************************
39 * LOCAL VARIABLES AND TABLES
40 ********************************************************************************
41 */
42
43 /*
44 ********************************************************************************
45 * LOCAL PROGRAM CODE
46 ********************************************************************************
47 */
48 /*************************************************************************
49 *
50 * FUNCTION: Get_lsp_pol
51 *
52 * PURPOSE: Find the polynomial F1(z) or F2(z) from the LSPs.
53 * If the LSP vector is passed at address 0 F1(z) is computed
54 * and if it is passed at address 1 F2(z) is computed.
55 *
56 * DESCRIPTION:
57 * This is performed by expanding the product polynomials:
58 *
59 * F1(z) = product ( 1 - 2 lsp[i] z^-1 + z^-2 )
60 * i=0,2,4,6,8
61 * F2(z) = product ( 1 - 2 lsp[i] z^-1 + z^-2 )
62 * i=1,3,5,7,9
63 *
64 * where lsp[] is the LSP vector in the cosine domain.
65 *
66 * The expansion is performed using the following recursion:
67 *
68 * f[0] = 1
69 * b = -2.0 * lsp[0]
70 * f[1] = b
71 * for i=2 to 5 do
72 * b = -2.0 * lsp[2*i-2];
73 * f[i] = b*f[i-1] + 2.0*f[i-2];
74 * for j=i-1 down to 2 do
75 * f[j] = f[j] + b*f[j-1] + f[j-2];
76 * f[1] = f[1] + b;
77 *
78 *************************************************************************/
79
80 static void Get_lsp_pol (Word16 *lsp, Word32 *f)
81 {
82 Word16 i, j, hi, lo;
83 Word32 t0;
84
85 /* f[0] = 1.0; */
86 *f = L_mult (4096, 2048); move32 ();
87 f++; move32 ();
88 *f = L_msu ((Word32) 0, *lsp, 512); /* f[1] = -2.0 * lsp[0]; */
89 f++; move32 ();
90 lsp += 2; /* Advance lsp pointer */
91
92 for (i = 2; i <= 5; i++)
93 {
94 *f = f[-2]; move32 ();
95
96 for (j = 1; j < i; j++, f--)
97 {
98 L_Extract (f[-1], &hi, &lo);
99 t0 = Mpy_32_16 (hi, lo, *lsp); /* t0 = f[-1] * lsp */
100 t0 = L_shl (t0, 1);
101 *f = L_add (*f, f[-2]); move32 (); /* *f += f[-2] */
102 *f = L_sub (*f, t0);move32 (); /* *f -= t0 */
103 }
104 *f = L_msu (*f, *lsp, 512); move32 (); /* *f -= lsp<<9 */
105 f += i; /* Advance f pointer */
106 lsp += 2; /* Advance lsp pointer */
107 }
108
109 return;
110 }
111
112 /*
113 ********************************************************************************
114 * PUBLIC PROGRAM CODE
115 ********************************************************************************
116 */
117 /*************************************************************************
118 *
119 * FUNCTION: Lsp_Az
120 *
121 * PURPOSE: Converts from the line spectral pairs (LSP) to
122 * LP coefficients, for a 10th order filter.
123 *
124 * DESCRIPTION:
125 * - Find the coefficients of F1(z) and F2(z) (see Get_lsp_pol)
126 * - Multiply F1(z) by 1+z^{-1} and F2(z) by 1-z^{-1}
127 * - A(z) = ( F1(z) + F2(z) ) / 2
128 *
129 *************************************************************************/
130 void Lsp_Az (
131 Word16 lsp[], /* (i) : line spectral frequencies */
132 Word16 a[] /* (o) : predictor coefficients (order = 10) */
133 )
134 {
135 Word16 i, j;
136 Word32 f1[6], f2[6];
137 Word32 t0;
138
139 Get_lsp_pol (&lsp[0], f1);
140 Get_lsp_pol (&lsp[1], f2);
141
142 for (i = 5; i > 0; i--)
143 {
144 f1[i] = L_add (f1[i], f1[i - 1]); move32 (); /* f1[i] += f1[i-1]; */
145 f2[i] = L_sub (f2[i], f2[i - 1]); move32 (); /* f2[i] -= f2[i-1]; */
146 }
147
148 a[0] = 4096; move16 ();
149 for (i = 1, j = 10; i <= 5; i++, j--)
150 {
151 t0 = L_add (f1[i], f2[i]); /* f1[i] + f2[i] */
152 a[i] = extract_l (L_shr_r (t0, 13)); move16 ();
153 t0 = L_sub (f1[i], f2[i]); /* f1[i] - f2[i] */
154 a[j] = extract_l (L_shr_r (t0, 13)); move16 ();
155 }
156
157 return;
158 }
159