196 lines
6.9 KiB
C
196 lines
6.9 KiB
C
/*
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* SpanDSP - a series of DSP components for telephony
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*
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* g711.c - A-law and u-law transcoding routines
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*
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* Written by Steve Underwood <steveu@coppice.org>
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*
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* Copyright (C) 2006 Steve Underwood
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License version 2.1,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/*! \file */
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#if defined(HAVE_CONFIG_H)
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#include "config.h"
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#endif
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#include <inttypes.h>
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#include <stdlib.h>
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#include <string.h>
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#include <assert.h>
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#include "spandsp/telephony.h"
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#include "spandsp/alloc.h"
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#include "spandsp/bit_operations.h"
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#include "spandsp/g711.h"
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#include "spandsp/private/g711.h"
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/* Copied from the CCITT G.711 specification */
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static const uint8_t ulaw_to_alaw_table[256] =
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{
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42, 43, 40, 41, 46, 47, 44, 45, 34, 35, 32, 33, 38, 39, 36, 37,
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58, 59, 56, 57, 62, 63, 60, 61, 50, 51, 48, 49, 54, 55, 52, 53,
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10, 11, 8, 9, 14, 15, 12, 13, 2, 3, 0, 1, 6, 7, 4, 26,
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27, 24, 25, 30, 31, 28, 29, 18, 19, 16, 17, 22, 23, 20, 21, 106,
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104, 105, 110, 111, 108, 109, 98, 99, 96, 97, 102, 103, 100, 101, 122, 120,
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126, 127, 124, 125, 114, 115, 112, 113, 118, 119, 116, 117, 75, 73, 79, 77,
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66, 67, 64, 65, 70, 71, 68, 69, 90, 91, 88, 89, 94, 95, 92, 93,
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82, 82, 83, 83, 80, 80, 81, 81, 86, 86, 87, 87, 84, 84, 85, 85,
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170, 171, 168, 169, 174, 175, 172, 173, 162, 163, 160, 161, 166, 167, 164, 165,
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186, 187, 184, 185, 190, 191, 188, 189, 178, 179, 176, 177, 182, 183, 180, 181,
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138, 139, 136, 137, 142, 143, 140, 141, 130, 131, 128, 129, 134, 135, 132, 154,
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155, 152, 153, 158, 159, 156, 157, 146, 147, 144, 145, 150, 151, 148, 149, 234,
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232, 233, 238, 239, 236, 237, 226, 227, 224, 225, 230, 231, 228, 229, 250, 248,
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254, 255, 252, 253, 242, 243, 240, 241, 246, 247, 244, 245, 203, 201, 207, 205,
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194, 195, 192, 193, 198, 199, 196, 197, 218, 219, 216, 217, 222, 223, 220, 221,
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210, 210, 211, 211, 208, 208, 209, 209, 214, 214, 215, 215, 212, 212, 213, 213
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};
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/* These transcoding tables are copied from the CCITT G.711 specification. To achieve
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optimal results, do not change them. */
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static const uint8_t alaw_to_ulaw_table[256] =
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{
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42, 43, 40, 41, 46, 47, 44, 45, 34, 35, 32, 33, 38, 39, 36, 37,
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57, 58, 55, 56, 61, 62, 59, 60, 49, 50, 47, 48, 53, 54, 51, 52,
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10, 11, 8, 9, 14, 15, 12, 13, 2, 3, 0, 1, 6, 7, 4, 5,
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26, 27, 24, 25, 30, 31, 28, 29, 18, 19, 16, 17, 22, 23, 20, 21,
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98, 99, 96, 97, 102, 103, 100, 101, 93, 93, 92, 92, 95, 95, 94, 94,
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116, 118, 112, 114, 124, 126, 120, 122, 106, 107, 104, 105, 110, 111, 108, 109,
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72, 73, 70, 71, 76, 77, 74, 75, 64, 65, 63, 63, 68, 69, 66, 67,
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86, 87, 84, 85, 90, 91, 88, 89, 79, 79, 78, 78, 82, 83, 80, 81,
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170, 171, 168, 169, 174, 175, 172, 173, 162, 163, 160, 161, 166, 167, 164, 165,
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185, 186, 183, 184, 189, 190, 187, 188, 177, 178, 175, 176, 181, 182, 179, 180,
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138, 139, 136, 137, 142, 143, 140, 141, 130, 131, 128, 129, 134, 135, 132, 133,
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154, 155, 152, 153, 158, 159, 156, 157, 146, 147, 144, 145, 150, 151, 148, 149,
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226, 227, 224, 225, 230, 231, 228, 229, 221, 221, 220, 220, 223, 223, 222, 222,
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244, 246, 240, 242, 252, 254, 248, 250, 234, 235, 232, 233, 238, 239, 236, 237,
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200, 201, 198, 199, 204, 205, 202, 203, 192, 193, 191, 191, 196, 197, 194, 195,
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214, 215, 212, 213, 218, 219, 216, 217, 207, 207, 206, 206, 210, 211, 208, 209
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};
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SPAN_DECLARE(uint8_t) alaw_to_ulaw(uint8_t alaw)
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{
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return alaw_to_ulaw_table[alaw];
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(uint8_t) ulaw_to_alaw(uint8_t ulaw)
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{
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return ulaw_to_alaw_table[ulaw];
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(int) g711_decode(g711_state_t *s,
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int16_t amp[],
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const uint8_t g711_data[],
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int g711_bytes)
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{
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int i;
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if (s->mode == G711_ALAW)
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{
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for (i = 0; i < g711_bytes; i++)
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amp[i] = alaw_to_linear(g711_data[i]);
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/*endfor*/
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}
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else
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{
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for (i = 0; i < g711_bytes; i++)
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amp[i] = ulaw_to_linear(g711_data[i]);
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/*endfor*/
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}
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/*endif*/
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return g711_bytes;
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(int) g711_encode(g711_state_t *s,
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uint8_t g711_data[],
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const int16_t amp[],
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int len)
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{
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int i;
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if (s->mode == G711_ALAW)
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{
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for (i = 0; i < len; i++)
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g711_data[i] = linear_to_alaw(amp[i]);
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/*endfor*/
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}
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else
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{
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for (i = 0; i < len; i++)
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g711_data[i] = linear_to_ulaw(amp[i]);
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/*endfor*/
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}
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/*endif*/
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return len;
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(int) g711_transcode(g711_state_t *s,
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uint8_t g711_out[],
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const uint8_t g711_in[],
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int g711_bytes)
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{
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int i;
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if (s->mode == G711_ALAW)
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{
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for (i = 0; i < g711_bytes; i++)
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g711_out[i] = alaw_to_ulaw_table[g711_in[i]];
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/*endfor*/
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}
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else
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{
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for (i = 0; i < g711_bytes; i++)
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g711_out[i] = ulaw_to_alaw_table[g711_in[i]];
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/*endfor*/
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}
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/*endif*/
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return g711_bytes;
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(g711_state_t *) g711_init(g711_state_t *s, int mode)
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{
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if (s == NULL)
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{
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if ((s = (g711_state_t *) span_alloc(sizeof(*s))) == NULL)
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return NULL;
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}
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s->mode = mode;
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return s;
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(int) g711_release(g711_state_t *s)
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{
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return 0;
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}
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/*- End of function --------------------------------------------------------*/
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SPAN_DECLARE(int) g711_free(g711_state_t *s)
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{
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span_free(s);
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return 0;
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}
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/*- End of function --------------------------------------------------------*/
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/*- End of file ------------------------------------------------------------*/
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