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comparison pcm/pcm_tx.c @ 7:ca351324187a

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pcm: implement Tx on the E1 timeslot
author Mychaela Falconia <falcon@freecalypso.org>
date Sun, 23 Jun 2024 19:21:00 +0000
parents
children 70aa8cbdbde9
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6:631f2db08538 7:ca351324187a
1 /*
2 * In this module we implement PCM Tx toward the TRAU.
3 */
4
5 #include <stdint.h>
6 #include <stdbool.h>
7 #include <stdio.h>
8 #include <stdlib.h>
9 #include <string.h>
10 #include <unistd.h>
11
12 #include <osmocom/core/select.h>
13
14 #include "globals.h"
15
16 static const uint8_t dmw_alaw[8] =
17 {0x34, 0x21, 0x21, 0x34, 0xB4, 0xA1, 0xA1, 0xB4};
18
19 static uint8_t pcm_fill_octet = 0x54;
20 static bool dmw_active;
21 static uint8_t *play_buffer;
22 static unsigned play_buf_nframes, play_buf_ptr;
23
24 static void fill_with_dmw(uint8_t *buf)
25 {
26 unsigned n;
27
28 for (n = 0; n < 20; n++) {
29 memcpy(buf, dmw_alaw, 8);
30 buf += 8;
31 }
32 }
33
34 static void fill_with_play(uint8_t *outbuf)
35 {
36 memcpy(outbuf, play_buffer + play_buf_ptr * 160, 160);
37 play_buf_ptr++;
38 if (play_buf_ptr < play_buf_nframes)
39 return;
40 free(play_buffer);
41 play_buffer = 0;
42 printf("file play finished\n");
43 }
44
45 void transmit_pcm_20ms(void)
46 {
47 uint8_t buf[160];
48
49 if (play_buffer)
50 fill_with_play(buf);
51 else if (dmw_active)
52 fill_with_dmw(buf);
53 else
54 memset(buf, pcm_fill_octet, 160);
55 write(ts_fd, buf, 160);
56 }