Bug fixed for unix error "readlink /proc/self/fd/0" on MacOS.
[Faustine.git] / interpreter / lib / src / libsndfile-1.0.25 / src / G72x / g723_16.c
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 /* 16kbps version created, used 24kbps code and changing as little as possible.
27 * G.726 specs are available from ITU's gopher or WWW site (http://www.itu.ch)
28 * If any errors are found, please contact me at mrand@tamu.edu
29 * -Marc Randolph
30 */
31
32 /*
33 * g723_16.c
34 *
35 * Description:
36 *
37 * g723_16_encoder(), g723_16_decoder()
38 *
39 * These routines comprise an implementation of the CCITT G.726 16 Kbps
40 * ADPCM coding algorithm. Essentially, this implementation is identical to
41 * the bit level description except for a few deviations which take advantage
42 * of workstation attributes, such as hardware 2's complement arithmetic.
43 *
44 */
45
46 #include "g72x.h"
47 #include "g72x_priv.h"
48
49 /*
50 * Maps G.723_16 code word to reconstructed scale factor normalized log
51 * magnitude values. Comes from Table 11/G.726
52 */
53 static short _dqlntab[4] = { 116, 365, 365, 116};
54
55 /* Maps G.723_16 code word to log of scale factor multiplier.
56 *
57 * _witab[4] is actually {-22 , 439, 439, -22}, but FILTD wants it
58 * as WI << 5 (multiplied by 32), so we'll do that here
59 */
60 static short _witab[4] = {-704, 14048, 14048, -704};
61
62 /*
63 * Maps G.723_16 code words to a set of values whose long and short
64 * term averages are computed and then compared to give an indication
65 * how stationary (steady state) the signal is.
66 */
67
68 /* Comes from FUNCTF */
69 static short _fitab[4] = {0, 0xE00, 0xE00, 0};
70
71 /* Comes from quantizer decision level tables (Table 7/G.726)
72 */
73 static short qtab_723_16[1] = {261};
74
75
76 /*
77 * g723_16_encoder()
78 *
79 * Encodes a linear PCM, A-law or u-law input sample and returns its 2-bit code.
80 * Returns -1 if invalid input coding value.
81 */
82 int
83 g723_16_encoder(
84 int sl,
85 G72x_STATE *state_ptr)
86 {
87 short sei, sezi, se, sez; /* ACCUM */
88 short d; /* SUBTA */
89 short y; /* MIX */
90 short sr; /* ADDB */
91 short dqsez; /* ADDC */
92 short dq, i;
93
94 /* linearize input sample to 14-bit PCM */
95 sl >>= 2; /* sl of 14-bit dynamic range */
96
97 sezi = predictor_zero(state_ptr);
98 sez = sezi >> 1;
99 sei = sezi + predictor_pole(state_ptr);
100 se = sei >> 1; /* se = estimated signal */
101
102 d = sl - se; /* d = estimation diff. */
103
104 /* quantize prediction difference d */
105 y = step_size(state_ptr); /* quantizer step size */
106 i = quantize(d, y, qtab_723_16, 1); /* i = ADPCM code */
107
108 /* Since quantize() only produces a three level output
109 * (1, 2, or 3), we must create the fourth one on our own
110 */
111 if (i == 3) /* i code for the zero region */
112 if ((d & 0x8000) == 0) /* If d > 0, i=3 isn't right... */
113 i = 0;
114
115 dq = reconstruct(i & 2, _dqlntab[i], y); /* quantized diff. */
116
117 sr = (dq < 0) ? se - (dq & 0x3FFF) : se + dq; /* reconstructed signal */
118
119 dqsez = sr + sez - se; /* pole prediction diff. */
120
121 update(2, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
122
123 return (i);
124 }
125
126 /*
127 * g723_16_decoder()
128 *
129 * Decodes a 2-bit CCITT G.723_16 ADPCM code and returns
130 * the resulting 16-bit linear PCM, A-law or u-law sample value.
131 * -1 is returned if the output coding is unknown.
132 */
133 int
134 g723_16_decoder(
135 int i,
136 G72x_STATE *state_ptr)
137 {
138 short sezi, sei, sez, se; /* ACCUM */
139 short y; /* MIX */
140 short sr; /* ADDB */
141 short dq;
142 short dqsez;
143
144 i &= 0x03; /* mask to get proper bits */
145 sezi = predictor_zero(state_ptr);
146 sez = sezi >> 1;
147 sei = sezi + predictor_pole(state_ptr);
148 se = sei >> 1; /* se = estimated signal */
149
150 y = step_size(state_ptr); /* adaptive quantizer step size */
151 dq = reconstruct(i & 0x02, _dqlntab[i], y); /* unquantize pred diff */
152
153 sr = (dq < 0) ? (se - (dq & 0x3FFF)) : (se + dq); /* reconst. signal */
154
155 dqsez = sr - se + sez; /* pole prediction diff. */
156
157 update(2, y, _witab[i], _fitab[i], dq, sr, dqsez, state_ptr);
158
159 /* sr was of 14-bit dynamic range */
160 return (sr << 2);
161 }
162