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
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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.
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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 "wx/wxprec.h"
49#include "wx/mmedia/internal/g72x.h"
50
51/*
52 * Maps G.723_40 code word to ructeconstructed scale factor normalized log
53 * magnitude values.
54 */
55static short _dqlntab[32] = {-2048, -66, 28, 104, 169, 224, 274, 318,
56                358, 395, 429, 459, 488, 514, 539, 566,
57                566, 539, 514, 488, 459, 429, 395, 358,
58                318, 274, 224, 169, 104, 28, -66, -2048};
59
60/* Maps G.723_40 code word to log of scale factor multiplier. */
61static short _witab[32] = {448, 448, 768, 1248, 1280, 1312, 1856, 3200,
62            4512, 5728, 7008, 8960, 11456, 14080, 16928, 22272,
63            22272, 16928, 14080, 11456, 8960, 7008, 5728, 4512,
64            3200, 1856, 1312, 1280, 1248, 768, 448, 448};
65
66/*
67 * Maps G.723_40 code words to a set of values whose long and short
68 * term averages are computed and then compared to give an indication
69 * how stationary (steady state) the signal is.
70 */
71static short _fitab[32] = {0, 0, 0, 0, 0, 0x200, 0x200, 0x200,
72            0x200, 0x200, 0x400, 0x600, 0x800, 0xA00, 0xC00, 0xC00,
73            0xC00, 0xC00, 0xA00, 0x800, 0x600, 0x400, 0x200, 0x200,
74            0x200, 0x200, 0x200, 0, 0, 0, 0, 0};
75
76static short qtab_723_40[15] = {-122, -16, 68, 139, 198, 250, 298, 339,
77                378, 413, 445, 475, 502, 528, 553};
78
79/*
80 * g723_40_encoder()
81 *
82 * Encodes a 16-bit linear PCM, A-law or u-law input sample and retuens
83 * the resulting 5-bit CCITT G.723 40Kbps code.
84 * Returns -1 if the input coding value is invalid.
85 */
86int
87g723_40_encoder(
88    int                sl,
89    int                in_coding,
90    struct g72x_state *state_ptr)
91{
92    short        sei, sezi, se, sez;    /* ACCUM */
93    short        d;                     /* SUBTA */
94    short        y;                     /* MIX */
95    short        sr;                    /* ADDB */
96    short        dqsez;                 /* ADDC */
97    short        dq, i;
98
99    switch (in_coding) {    /* linearize input sample to 14-bit PCM */
100    case AUDIO_ENCODING_ALAW:
101        sl = alaw2linear(sl) >> 2;
102        break;
103    case AUDIO_ENCODING_ULAW:
104        sl = ulaw2linear(sl) >> 2;
105        break;
106    case AUDIO_ENCODING_LINEAR:
107        sl = ((short) sl) >> 2;        /* sl of 14-bit dynamic range */
108        break;
109    default:
110        return (-1);
111    }
112
113    sezi = predictor_zero(state_ptr);
114    sez = sezi >> 1;
115    sei = sezi + predictor_pole(state_ptr);
116    se = sei >> 1;            /* se = estimated signal */
117
118    d = sl - se;            /* d = estimation difference */
119
120    /* quantize prediction difference */
121    y = step_size(state_ptr);    /* adaptive quantizer step size */
122    i = quantize(d, y, qtab_723_40, 15);    /* i = ADPCM code */
123
124    dq = reconstruct(i & 0x10, _dqlntab[i], y);    /* quantized diff */
125
126    sr = (dq < 0) ? se - (dq & 0x7FFF) : se + dq; /* reconstructed signal */
127
128    dqsez = sr + sez - se;        /* dqsez = pole prediction diff. */
129
130    update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
131
132    return (i);
133}
134
135/*
136 * g723_40_decoder()
137 *
138 * Decodes a 5-bit CCITT G.723 40Kbps code and returns
139 * the resulting 16-bit linear PCM, A-law or u-law sample value.
140 * -1 is returned if the output coding is unknown.
141 */
142int
143g723_40_decoder(
144    int                i,
145    int                out_coding,
146    struct g72x_state *state_ptr)
147{
148    short        sezi, sei, sez, se;    /* ACCUM */
149    short        y;                     /* MIX */
150    short        sr;                    /* ADDB */
151    short        dq;
152    short        dqsez;
153
154    i &= 0x1f;            /* mask to get proper bits */
155    sezi = predictor_zero(state_ptr);
156    sez = sezi >> 1;
157    sei = sezi + predictor_pole(state_ptr);
158    se = sei >> 1;            /* se = estimated signal */
159
160    y = step_size(state_ptr);    /* adaptive quantizer step size */
161    dq = reconstruct(i & 0x10, _dqlntab[i], y);    /* estimation diff. */
162
163    sr = (dq < 0) ? (se - (dq & 0x7FFF)) : (se + dq); /* reconst. signal */
164
165    dqsez = sr - se + sez;        /* pole prediction diff. */
166
167    update(5, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
168
169    switch (out_coding) {
170    case AUDIO_ENCODING_ALAW:
171        return (tandem_adjust_alaw(sr, se, y, i, 0x10, qtab_723_40));
172    case AUDIO_ENCODING_ULAW:
173        return (tandem_adjust_ulaw(sr, se, y, i, 0x10, qtab_723_40));
174    case AUDIO_ENCODING_LINEAR:
175        return (sr << 2);    /* sr was of 14-bit dynamic range */
176    default:
177        return (-1);
178    }
179}
180