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1/*
2 * This source code is a product of Sun Microsystems, Inc. and is provided
3 * for unrestricted use. Users may copy or modify this source code without
4 * charge.
5 *
6 * SUN SOURCE CODE IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING
7 * THE WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
8 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
9 *
10 * Sun source code is provided with no support and without any obligation on
11 * the part of Sun Microsystems, Inc. to assist in its use, correction,
12 * modification or enhancement.
13 *
14 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
15 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY THIS SOFTWARE
16 * OR ANY PART THEREOF.
17 *
18 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
19 * or profits or other special, indirect and consequential damages, even if
20 * Sun has been advised of the possibility of such damages.
21 *
22 * Sun Microsystems, Inc.
23 * 2550 Garcia Avenue
24 * Mountain View, California 94043
25 */
26
27/*
28 * g723_40.c
29 *
30 * Description:
31 *
32 * g723_40_encoder(), g723_40_decoder()
33 *
34 * These routines comprise an implementation of the CCITT G.723 40Kbps
35 * ADPCM coding algorithm. Essentially, this implementation is identical to
36 * the bit level description except for a few deviations which
37 * take advantage of workstation attributes, such as hardware 2's
38 * complement arithmetic.
39 *
40 * The deviation from the bit level specification (lookup tables),
41 * preserves the bit level performance specifications.
42 *
43 * As outlined in the G.723 Recommendation, the algorithm is broken
44 * down into modules. Each section of code below is preceded by
45 * the name of the module which it is implementing.
46 *
47 */
48#include "g72x.h"
49
50/*
51 * Maps G.723_40 code word to ructeconstructed scale factor normalized log
52 * magnitude values.
53 */
54static short _dqlntab[32] = {-2048, -66, 28, 104, 169, 224, 274, 318,
55 358, 395, 429, 459, 488, 514, 539, 566,
56 566, 539, 514, 488, 459, 429, 395, 358,
57 318, 274, 224, 169, 104, 28, -66, -2048};
58
59/* Maps G.723_40 code word to log of scale factor multiplier. */
60static short _witab[32] = {448, 448, 768, 1248, 1280, 1312, 1856, 3200,
61 4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272,
62 22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512,
63 3200, 1856, 1312, 1280, 1248, 768, 448, 448};
64
65/*
66 * Maps G.723_40 code words to a set of values whose long and short
67 * term averages are computed and then compared to give an indication
68 * how stationary (steady state) the signal is.
69 */
70static short _fitab[32] = {0, 0, 0, 0, 0, 0x200, 0x200, 0x200,
71 0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00,
72 0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200,
73 0x200, 0x200, 0x200, 0, 0, 0, 0, 0};
74
75static short qtab_723_40[15] = {-122, -16, 68, 139, 198, 250, 298, 339,
76 378, 413, 445, 475, 502, 528, 553};
77
78/*
79 * g723_40_encoder()
80 *
81 * Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens
82 * the resulting 5-bit CCITT G.723 40Kbps code.
83 * Returns -1 if the input coding value is invalid.
84 */
85int
86g723_40_encoder(
87 int sl,
88 int in_coding,
89 struct g72x_state *state_ptr)
90{
91 short sei, sezi, se, sez; /* ACCUM */
92 short d; /* SUBTA */
93 short y; /* MIX */
94 short sr; /* ADDB */
95 short dqsez; /* ADDC */
96 short dq, i;
97
98 switch (in_coding) { /* linearize input sample to 14-bit PCM */
99 case AUDIO_ENCODING_ALAW:
100 sl = alaw2linear(sl) >> 2;
101 break;
102 case AUDIO_ENCODING_ULAW:
103 sl = ulaw2linear(sl) >> 2;
104 break;
105 case AUDIO_ENCODING_LINEAR:
106 sl = ((short) sl) >> 2; /* sl of 14-bit dynamic range */
107 break;
108 default:
109 return (-1);
110 }
111
112 sezi = predictor_zero(state_ptr);
113 sez = sezi >> 1;
114 sei = sezi + predictor_pole(state_ptr);
115 se = sei >> 1; /* se = estimated signal */
116
117 d = sl - se; /* d = estimation difference */
118
119 /* quantize prediction difference */
120 y = step_size(state_ptr); /* adaptive quantizer step size */
121 i = quantize(d, y, qtab_723_40, 15); /* i = ADPCM code */
122
123 dq = reconstruct(i & 0x10, _dqlntab[i], y); /* quantized diff */
124
125 sr = (dq < 0) ? se - (dq & 0x7FFF) : se + dq; /* reconstructed signal */
126
127 dqsez = sr + sez - se; /* dqsez = pole prediction diff. */
128
129 update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
130
131 return (i);
132}
133
134/*
135 * g723_40_decoder()
136 *
137 * Decodes a 5-bit CCITT G.723 40Kbps code and returns
138 * the resulting 16-bit linear PCM, A-law or u-law sample value.
139 * -1 is returned if the output coding is unknown.
140 */
141int
142g723_40_decoder(
143 int i,
144 int out_coding,
145 struct g72x_state *state_ptr)
146{
147 short sezi, sei, sez, se; /* ACCUM */
148 short y; /* MIX */
149 short sr; /* ADDB */
150 short dq;
151 short dqsez;
152
153 i &= 0x1f; /* mask to get proper bits */
154 sezi = predictor_zero(state_ptr);
155 sez = sezi >> 1;
156 sei = sezi + predictor_pole(state_ptr);
157 se = sei >> 1; /* se = estimated signal */
158
159 y = step_size(state_ptr); /* adaptive quantizer step size */
160 dq = reconstruct(i & 0x10, _dqlntab[i], y); /* estimation diff. */
161
162 sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq); /* reconst. signal */
163
164 dqsez = sr - se + sez; /* pole prediction diff. */
165
166 update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
167
168 switch (out_coding) {
169 case AUDIO_ENCODING_ALAW:
170 return (tandem_adjust_alaw(sr, se, y, i, 0x10, qtab_723_40));
171 case AUDIO_ENCODING_ULAW:
172 return (tandem_adjust_ulaw(sr, se, y, i, 0x10, qtab_723_40));
173 case AUDIO_ENCODING_LINEAR:
174 return (sr << 2); /* sr was of 14-bit dynamic range */
175 default:
176 return (-1);
177 }
178}