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
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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_24.c
29 *
30 * Description:
31 *
32 * g723_24_encoder(), g723_24_decoder()
33 *
34 * These routines comprise an implementation of the CCITT G.723 24 Kbps
35 * ADPCM coding algorithm.  Essentially, this implementation is identical to
36 * the bit level description except for a few deviations which take advantage
37 * of workstation attributes, such as hardware 2's complement arithmetic.
38 *
39 */
40#include "wx/wxprec.h"
41#include "wx/mmedia/internal/g72x.h"
42
43/*
44 * Maps G.723_24 code word to reconstructed scale factor normalized log
45 * magnitude values.
46 */
47static short _dqlntab[8] = {-2048, 135, 273, 373, 373, 273, 135, -2048};
48
49/* Maps G.723_24 code word to log of scale factor multiplier. */
50static short _witab[8] = {-128, 960, 4384, 18624, 18624, 4384, 960, -128};
51
52/*
53 * Maps G.723_24 code words to a set of values whose long and short
54 * term averages are computed and then compared to give an indication
55 * how stationary (steady state) the signal is.
56 */
57static short _fitab[8] = {0, 0x200, 0x400, 0xE00, 0xE00, 0x400, 0x200, 0};
58
59static short qtab_723_24[3] = {8, 218, 331};
60
61/*
62 * g723_24_encoder()
63 *
64 * Encodes a linear PCM, A-law or u-law input sample and returns its 3-bit code.
65 * Returns -1 if invalid input coding value.
66 */
67int
68g723_24_encoder(
69    int                sl,
70    int                in_coding,
71    struct g72x_state *state_ptr)
72{
73    short        sei, sezi, se, sez;    /* ACCUM */
74    short        d;                     /* SUBTA */
75    short        y;                     /* MIX */
76    short        sr;                    /* ADDB */
77    short        dqsez;                 /* ADDC */
78    short        dq, i;
79
80    switch (in_coding) {    /* linearize input sample to 14-bit PCM */
81    case AUDIO_ENCODING_ALAW:
82        sl = alaw2linear(sl) >> 2;
83        break;
84    case AUDIO_ENCODING_ULAW:
85        sl = ulaw2linear(sl) >> 2;
86        break;
87    case AUDIO_ENCODING_LINEAR:
88        sl = ((short)sl) >> 2;        /* sl of 14-bit dynamic range */
89        break;
90    default:
91        return (-1);
92    }
93
94    sezi = predictor_zero(state_ptr);
95    sez = sezi >> 1;
96    sei = sezi + predictor_pole(state_ptr);
97    se = sei >> 1;            /* se = estimated signal */
98
99    d = sl - se;            /* d = estimation diff. */
100
101    /* quantize prediction difference d */
102    y = step_size(state_ptr);    /* quantizer step size */
103    i = quantize(d, y, qtab_723_24, 3);    /* i = ADPCM code */
104    dq = reconstruct(i & 4, _dqlntab[i], y); /* quantized diff. */
105
106    sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */
107
108    dqsez = sr + sez - se;        /* pole prediction diff. */
109
110    update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
111
112    return (i);
113}
114
115/*
116 * g723_24_decoder()
117 *
118 * Decodes a 3-bit CCITT G.723_24 ADPCM code and returns
119 * the resulting 16-bit linear PCM, A-law or u-law sample value.
120 * -1 is returned if the output coding is unknown.
121 */
122int
123g723_24_decoder(
124    int                i,
125    int                out_coding,
126    struct g72x_state *state_ptr)
127{
128    short        sezi, sei, sez, se;    /* ACCUM */
129    short        y;                     /* MIX */
130    short        sr;                    /* ADDB */
131    short        dq;
132    short        dqsez;
133
134    i &= 0x07;            /* mask to get proper bits */
135    sezi = predictor_zero(state_ptr);
136    sez = sezi >> 1;
137    sei = sezi + predictor_pole(state_ptr);
138    se = sei >> 1;            /* se = estimated signal */
139
140    y = step_size(state_ptr);    /* adaptive quantizer step size */
141    dq = reconstruct(i & 0x04, _dqlntab[i], y); /* unquantize pred diff */
142
143    sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */
144
145    dqsez = sr - se + sez;            /* pole prediction diff. */
146
147    update(3, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
148
149    switch (out_coding) {
150    case AUDIO_ENCODING_ALAW:
151        return (tandem_adjust_alaw(sr, se, y, i, 4, qtab_723_24));
152    case AUDIO_ENCODING_ULAW:
153        return (tandem_adjust_ulaw(sr, se, y, i, 4, qtab_723_24));
154    case AUDIO_ENCODING_LINEAR:
155        return (sr << 2);    /* sr was of 14-bit dynamic range */
156    default:
157        return (-1);
158    }
159}
160