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      1 /*
      2  * SpanDSP - a series of DSP components for telephony
      3  *
      4  * g711.c - A-law and u-law transcoding routines
      5  *
      6  * Written by Steve Underwood <steveu (at) coppice.org>
      7  *
      8  * Copyright (C) 2006 Steve Underwood
      9  *
     10  *  Despite my general liking of the GPL, I place this code in the
     11  *  public domain for the benefit of all mankind - even the slimy
     12  *  ones who might try to proprietize my work and use it to my
     13  *  detriment.
     14  *
     15  * $Id: g711.c,v 1.1 2006/06/07 15:46:39 steveu Exp $
     16  *
     17  * Modifications for WebRtc, 2011/04/28, by tlegrand:
     18  * -Removed unused include files
     19  * -Changed to use WebRtc types
     20  * -Added option to run encoder bitexact with ITU-T reference implementation
     21  */
     22 
     23 #include "g711.h"
     24 #include "webrtc/typedefs.h"
     25 
     26 /* Copied from the CCITT G.711 specification */
     27 static const uint8_t ulaw_to_alaw_table[256] = {
     28    42,  43,  40,  41,  46,  47,  44,  45,  34,  35,  32,  33,  38,  39,  36,
     29    37,  58,  59,  56,  57,  62,  63,  60,  61,  50,  51,  48,  49,  54,  55,
     30    52,  53,  10,  11,   8,   9,  14,  15,  12,  13,   2,   3,   0,   1,   6,
     31     7,   4,  26,  27,  24,  25,  30,  31,  28,  29,  18,  19,  16,  17,  22,
     32    23,  20,  21, 106, 104, 105, 110, 111, 108, 109,  98,  99,  96,  97, 102,
     33   103, 100, 101, 122, 120, 126, 127, 124, 125, 114, 115, 112, 113, 118, 119,
     34   116, 117,  75,  73,  79,  77,  66,  67,  64,  65,  70,  71,  68,  69,  90,
     35    91,  88,  89,  94,  95,  92,  93,  82,  82,  83,  83,  80,  80,  81,  81,
     36    86,  86,  87,  87,  84,  84,  85,  85, 170, 171, 168, 169, 174, 175, 172,
     37   173, 162, 163, 160, 161, 166, 167, 164, 165, 186, 187, 184, 185, 190, 191,
     38   188, 189, 178, 179, 176, 177, 182, 183, 180, 181, 138, 139, 136, 137, 142,
     39   143, 140, 141, 130, 131, 128, 129, 134, 135, 132, 154, 155, 152, 153, 158,
     40   159, 156, 157, 146, 147, 144, 145, 150, 151, 148, 149, 234, 232, 233, 238,
     41   239, 236, 237, 226, 227, 224, 225, 230, 231, 228, 229, 250, 248, 254, 255,
     42   252, 253, 242, 243, 240, 241, 246, 247, 244, 245, 203, 201, 207, 205, 194,
     43   195, 192, 193, 198, 199, 196, 197, 218, 219, 216, 217, 222, 223, 220, 221,
     44   210, 210, 211, 211, 208, 208, 209, 209, 214, 214, 215, 215, 212, 212, 213,
     45   213
     46 };
     47 
     48 /* These transcoding tables are copied from the CCITT G.711 specification. To
     49    achieve optimal results, do not change them. */
     50 static const uint8_t alaw_to_ulaw_table[256] = {
     51    42,  43,  40,  41,  46,  47,  44,  45,  34,  35,  32,  33,  38,  39,  36,
     52    37,  57,  58,  55,  56,  61,  62,  59,  60,  49,  50,  47,  48,  53,  54,
     53    51,  52,  10,  11,   8,   9,  14,  15,  12,  13,   2,   3,   0,   1,   6,
     54     7,   4,   5,  26,  27,  24,  25,  30,  31,  28,  29,  18,  19,  16,  17,
     55    22,  23,  20,  21,  98,  99,  96,  97, 102, 103, 100, 101,  93,  93,  92,
     56    92,  95,  95,  94,  94, 116, 118, 112, 114, 124, 126, 120, 122, 106, 107,
     57   104, 105, 110, 111, 108, 109,  72,  73,  70,  71,  76,  77,  74,  75,  64,
     58    65,  63,  63,  68,  69,  66,  67,  86,  87,  84,  85,  90,  91,  88,  89,
     59    79,  79,  78,  78,  82,  83,  80,  81, 170, 171, 168, 169, 174, 175, 172,
     60   173, 162, 163, 160, 161, 166, 167, 164, 165, 185, 186, 183, 184, 189, 190,
     61   187, 188, 177, 178, 175, 176, 181, 182, 179, 180, 138, 139, 136, 137, 142,
     62   143, 140, 141, 130, 131, 128, 129, 134, 135, 132, 133, 154, 155, 152, 153,
     63   158, 159, 156, 157, 146, 147, 144, 145, 150, 151, 148, 149, 226, 227, 224,
     64   225, 230, 231, 228, 229, 221, 221, 220, 220, 223, 223, 222, 222, 244, 246,
     65   240, 242, 252, 254, 248, 250, 234, 235, 232, 233, 238, 239, 236, 237, 200,
     66   201, 198, 199, 204, 205, 202, 203, 192, 193, 191, 191, 196, 197, 194, 195,
     67   214, 215, 212, 213, 218, 219, 216, 217, 207, 207, 206, 206, 210, 211, 208,
     68   209
     69 };
     70 
     71 uint8_t alaw_to_ulaw(uint8_t alaw) { return alaw_to_ulaw_table[alaw]; }
     72 
     73 uint8_t ulaw_to_alaw(uint8_t ulaw) { return ulaw_to_alaw_table[ulaw]; }
     74