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xmit.c
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//
// This file is part of Dire Wolf, an amateur radio packet TNC.
//
// Copyright (C) 2011, 2013, 2014, 2015, 2016, 2017 John Langner, WB2OSZ
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
//
/*------------------------------------------------------------------
*
* Module: xmit.c
*
* Purpose: Transmit queued up packets when channel is clear.
*
* Description: Producers of packets to be transmitted call tq_append and then
* go merrily on their way, unconcerned about when the packet might
* actually get transmitted.
*
* This thread waits until the channel is clear and then removes
* packets from the queue and transmits them.
*
*
* Usage: (1) The main application calls xmit_init.
*
* This will initialize the transmit packet queue
* and create a thread to empty the queue when
* the channel is clear.
*
* (2) The application queues up packets by calling tq_append.
*
* Packets that are being digipeated should go in the
* high priority queue so they will go out first.
*
* Other packets should go into the lower priority queue.
*
* (3) xmit_thread removes packets from the queue and transmits
* them when other signals are not being heard.
*
*---------------------------------------------------------------*/
#include "direwolf.h"
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <math.h>
#include <errno.h>
#include <stddef.h>
#include "direwolf.h"
#include "ax25_pad.h"
#include "textcolor.h"
#include "audio.h"
#include "tq.h"
#include "xmit.h"
#include "hdlc_send.h"
#include "hdlc_rec.h"
#include "ptt.h"
#include "dtime_now.h"
#include "morse.h"
#include "dtmf.h"
#include "xid.h"
#include "dlq.h"
#include "server.h"
/*
* Parameters for transmission.
* Each channel can have different timing values.
*
* These are initialized once at application startup time
* and some can be changed later by commands from connected applications.
*/
static int xmit_slottime[MAX_CHANS]; /* Slot time in 10 mS units for persistance algorithm. */
static int xmit_persist[MAX_CHANS]; /* Sets probability for transmitting after each */
/* slot time delay. Transmit if a random number */
/* in range of 0 - 255 <= persist value. */
/* Otherwise wait another slot time and try again. */
static int xmit_txdelay[MAX_CHANS]; /* After turning on the transmitter, */
/* send "flags" for txdelay * 10 mS. */
static int xmit_txtail[MAX_CHANS]; /* Amount of time to keep transmitting after we */
/* are done sending the data. This is to avoid */
/* dropping PTT too soon and chopping off the end */
/* of the frame. Again 10 mS units. */
static int xmit_fulldup[MAX_CHANS]; /* Full duplex if non-zero. */
static int xmit_bits_per_sec[MAX_CHANS]; /* Data transmission rate. */
/* Often called baud rate which is equivalent for */
/* 1200 & 9600 cases but could be different with other */
/* modulation techniques. */
static int g_debug_xmit_packet; /* print packet in hexadecimal form for debugging. */
// TODO: When this was first written, bits/sec was same as baud.
// Need to revisit this for PSK modes where they are not the same.
#if 0 // Added during 1.5 beta test
static int BITS_TO_MS (int b, int ch) {
int bits_per_symbol;
switch (save_audio_config_p->achan[ch].modem_type) {
case MODEM_QPSK: bits_per_symbol = 2; break;
case MODEM_8PSK: bits_per_symbol = 3; break;
case default: bits_per_symbol = 1; break;
}
return ( (b * 1000) / (xmit_bits_per_sec[(ch)] * bits_per_symbol) );
}
static int MS_TO_BITS (int ms, int ch) {
int bits_per_symbol;
switch (save_audio_config_p->achan[ch].modem_type) {
case MODEM_QPSK: bits_per_symbol = 2; break;
case MODEM_8PSK: bits_per_symbol = 3; break;
case default: bits_per_symbol = 1; break;
}
return ( (ms * xmit_bits_per_sec[(ch)] * bits_per_symbol) / 1000 ); TODO...
}
#else // OK for 1200, 9600 but wrong for PSK
#define BITS_TO_MS(b,ch) (((b)*1000)/xmit_bits_per_sec[(ch)])
#define MS_TO_BITS(ms,ch) (((ms)*xmit_bits_per_sec[(ch)])/1000)
#endif
#define MAXX(a,b) (((a)>(b)) ? (a) : (b))
#if __WIN32__
static unsigned __stdcall xmit_thread (void *arg);
#else
static void * xmit_thread (void *arg);
#endif
/*
* When an audio device is in stereo mode, we can have two
* different channels that want to transmit at the same time.
* We are not clever enough to multiplex them so use this
* so only one is activte at the same time.
*/
static dw_mutex_t audio_out_dev_mutex[MAX_ADEVS];
static int wait_for_clear_channel (int channel, int slotttime, int persist, int fulldup);
static void xmit_ax25_frames (int c, int p, packet_t pp, int max_bundle);
static int send_one_frame (int c, int p, packet_t pp);
static void xmit_speech (int c, packet_t pp);
static void xmit_morse (int c, packet_t pp, int wpm);
static void xmit_dtmf (int c, packet_t pp, int speed);
/*-------------------------------------------------------------------
*
* Name: xmit_init
*
* Purpose: Initialize the transmit process.
*
* Inputs: modem - Structure with modem and timing parameters.
*
*
* Outputs: Remember required information for future use.
*
* Description: Initialize the queue to be empty and set up other
* mechanisms for sharing it between different threads.
*
* Start up xmit_thread(s) to actually send the packets
* at the appropriate time.
*
* Version 1.2: We now allow multiple audio devices with one or two channels each.
* Each audio channel has its own thread.
*
*--------------------------------------------------------------------*/
static struct audio_s *save_audio_config_p;
void xmit_init (struct audio_s *p_modem, int debug_xmit_packet)
{
int j;
int ad;
#if __WIN32__
HANDLE xmit_th[MAX_CHANS];
#else
//pthread_attr_t attr;
//struct sched_param sp;
pthread_t xmit_tid[MAX_CHANS];
#endif
//int e;
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_init ( ... )\n");
#endif
save_audio_config_p = p_modem;
g_debug_xmit_packet = debug_xmit_packet;
/*
* Push to Talk (PTT) control.
*/
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_init: about to call ptt_init \n");
#endif
ptt_init (p_modem);
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_init: back from ptt_init \n");
#endif
/*
* Save parameters for later use.
* TODO1.2: Any reason to use global config rather than making a copy?
*/
for (j=0; j<MAX_CHANS; j++) {
xmit_bits_per_sec[j] = p_modem->achan[j].baud;
xmit_slottime[j] = p_modem->achan[j].slottime;
xmit_persist[j] = p_modem->achan[j].persist;
xmit_txdelay[j] = p_modem->achan[j].txdelay;
xmit_txtail[j] = p_modem->achan[j].txtail;
xmit_fulldup[j] = p_modem->achan[j].fulldup;
}
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_init: about to call tq_init \n");
#endif
tq_init (p_modem);
for (ad = 0; ad < MAX_ADEVS; ad++) {
dw_mutex_init (&(audio_out_dev_mutex[ad]));
}
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_init: about to create threads \n");
#endif
//TODO: xmit thread should be higher priority to avoid
// underrun on the audio output device.
for (j=0; j<MAX_CHANS; j++) {
if (p_modem->achan[j].medium == MEDIUM_RADIO) {
#if __WIN32__
xmit_th[j] = (HANDLE)_beginthreadex (NULL, 0, xmit_thread, (void*)(ptrdiff_t)j, 0, NULL);
if (xmit_th[j] == NULL) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("Could not create xmit thread %d\n", j);
return;
}
#else
int e;
#if 0
//TODO: not this simple. probably need FIFO policy.
pthread_attr_init (&attr);
e = pthread_attr_getschedparam (&attr, &sp);
if (e != 0) {
text_color_set(DW_COLOR_ERROR);
perror("pthread_attr_getschedparam");
}
text_color_set(DW_COLOR_ERROR);
dw_printf ("Default scheduling priority = %d, min=%d, max=%d\n",
sp.sched_priority,
sched_get_priority_min(SCHED_OTHER),
sched_get_priority_max(SCHED_OTHER));
sp.sched_priority--;
e = pthread_attr_setschedparam (&attr, &sp);
if (e != 0) {
text_color_set(DW_COLOR_ERROR);
perror("pthread_attr_setschedparam");
}
e = pthread_create (&(xmit_tid[j]), &attr, xmit_thread, (void *)(ptrdiff_t)j);
pthread_attr_destroy (&attr);
#else
e = pthread_create (&(xmit_tid[j]), NULL, xmit_thread, (void *)(ptrdiff_t)j);
#endif
if (e != 0) {
text_color_set(DW_COLOR_ERROR);
perror("Could not create xmit thread for audio device");
return;
}
#endif
}
}
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_init: finished \n");
#endif
} /* end tq_init */
/*-------------------------------------------------------------------
*
* Name: xmit_set_txdelay
* xmit_set_persist
* xmit_set_slottime
* xmit_set_txtail
* xmit_set_fulldup
*
*
* Purpose: The KISS protocol, and maybe others, can specify
* transmit timing parameters. If the application
* specifies these, they will override what was read
* from the configuration file.
*
* Inputs: channel - should be 0 or 1.
*
* value - time values are in 10 mSec units.
*
*
* Outputs: Remember required information for future use.
*
* Question: Should we have an option to enable or disable the
* application changing these values?
*
* Bugs: No validity checking other than array subscript out of bounds.
*
*--------------------------------------------------------------------*/
void xmit_set_txdelay (int channel, int value)
{
if (channel >= 0 && channel < MAX_CHANS) {
xmit_txdelay[channel] = value;
}
}
void xmit_set_persist (int channel, int value)
{
if (channel >= 0 && channel < MAX_CHANS) {
xmit_persist[channel] = value;
}
}
void xmit_set_slottime (int channel, int value)
{
if (channel >= 0 && channel < MAX_CHANS) {
xmit_slottime[channel] = value;
}
}
void xmit_set_txtail (int channel, int value)
{
if (channel >= 0 && channel < MAX_CHANS) {
xmit_txtail[channel] = value;
}
}
void xmit_set_fulldup (int channel, int value)
{
if (channel >= 0 && channel < MAX_CHANS) {
xmit_fulldup[channel] = value;
}
}
/*-------------------------------------------------------------------
*
* Name: frame_flavor
*
* Purpose: Separate frames into different flavors so we can decide
* which can be bundled into a single transmission and which should
* be sent separately.
*
* Inputs: pp - Packet object.
*
* Returns: Flavor, one of:
*
* FLAVOR_SPEECH - Destination address is SPEECH.
* FLAVOR_MORSE - Destination address is MORSE.
* FLAVOR_DTMF - Destination address is DTMF.
* FLAVOR_APRS_NEW - APRS original, i.e. not digipeating.
* FLAVOR_APRS_DIGI - APRS digipeating.
* FLAVOR_OTHER - Anything left over, i.e. connected mode.
*
*--------------------------------------------------------------------*/
typedef enum flavor_e { FLAVOR_APRS_NEW, FLAVOR_APRS_DIGI, FLAVOR_SPEECH, FLAVOR_MORSE, FLAVOR_DTMF, FLAVOR_OTHER } flavor_t;
static flavor_t frame_flavor (packet_t pp)
{
if (ax25_is_aprs (pp)) { // UI frame, PID 0xF0.
// It's unfortunate APRS did not use its own special PID.
char dest[AX25_MAX_ADDR_LEN];
ax25_get_addr_no_ssid(pp, AX25_DESTINATION, dest);
if (strcmp(dest, "SPEECH") == 0) {
return (FLAVOR_SPEECH);
}
if (strcmp(dest, "MORSE") == 0) {
return (FLAVOR_MORSE);
}
if (strcmp(dest, "DTMF") == 0) {
return (FLAVOR_DTMF);
}
/* Is there at least one digipeater AND has first one been used? */
/* I could be the first in the list or later. Doesn't matter. */
if (ax25_get_num_repeaters(pp) >= 1 && ax25_get_h(pp,AX25_REPEATER_1)) {
return (FLAVOR_APRS_DIGI);
}
return (FLAVOR_APRS_NEW);
}
return (FLAVOR_OTHER);
} /* end frame_flavor */
/*-------------------------------------------------------------------
*
* Name: xmit_thread
*
* Purpose: Process transmit queue for one channel.
*
* Inputs: transmit packet queue.
*
* Outputs:
*
* Description: We have different timing rules for different types of
* packets so they are put into different queues.
*
* High Priority -
*
* Packets which are being digipeated go out first.
* Latest recommendations are to retransmit these
* immdediately (after no one else is heard, of course)
* rather than waiting random times to avoid collisions.
* The KPC-3 configuration option for this is "UIDWAIT OFF". (?)
*
* AX.25 connected mode also has a couple cases
* where "expedited" frames are sent.
*
* Low Priority -
*
* Other packets are sent after a random wait time
* (determined by PERSIST & SLOTTIME) to help avoid
* collisions.
*
* If more than one audio channel is being used, a separate
* pair of transmit queues is used for each channel.
*
*
*
* Version 1.2: Allow more than one audio device.
* each channel has its own thread.
* Add speech capability.
*
* Version 1.4: Rearranged logic for bundling multiple frames into a single transmission.
*
* The rule is that Speech, Morse Code, DTMF, and APRS digipeated frames
* are all sent separately. The rest can be bundled.
*
*--------------------------------------------------------------------*/
#if __WIN32__
static unsigned __stdcall xmit_thread (void *arg)
#else
static void * xmit_thread (void *arg)
#endif
{
int chan = (int)(ptrdiff_t)arg; // channel number.
packet_t pp;
int prio;
int ok;
while (1) {
tq_wait_while_empty (chan);
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_thread, channel %d: woke up\n", chan);
#endif
// Does this extra loop offer any benefit?
while (tq_peek(chan, TQ_PRIO_0_HI) != NULL || tq_peek(chan, TQ_PRIO_1_LO) != NULL) {
/*
* Wait for the channel to be clear.
* If there is something in the high priority queue, begin transmitting immediately.
* Otherwise, wait a random amount of time, in hopes of minimizing collisions.
*/
ok = wait_for_clear_channel (chan, xmit_slottime[chan], xmit_persist[chan], xmit_fulldup[chan]);
prio = TQ_PRIO_1_LO;
pp = tq_remove (chan, TQ_PRIO_0_HI);
if (pp != NULL) {
prio = TQ_PRIO_0_HI;
}
else {
pp = tq_remove (chan, TQ_PRIO_1_LO);
}
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_thread: tq_remove(chan=%d, prio=%d) returned %p\n", chan, prio, pp);
#endif
// Shouldn't have NULL here but be careful.
if (pp != NULL) {
if (ok) {
/*
* Channel is clear and we have lock on output device.
*
* If destination is "SPEECH" send info part to speech synthesizer.
* If destination is "MORSE" send as morse code.
* If destination is "DTMF" send as Touch Tones.
*/
int ssid, wpm, speed;
switch (frame_flavor(pp)) {
case FLAVOR_SPEECH:
xmit_speech (chan, pp);
break;
case FLAVOR_MORSE:
ssid = ax25_get_ssid(pp, AX25_DESTINATION);
wpm = (ssid > 0) ? (ssid * 2) : MORSE_DEFAULT_WPM;
// This is a bit of a hack so we don't respond too quickly for APRStt.
// It will be sent in high priority queue while a beacon wouldn't.
// Add a little delay so user has time release PTT after sending #.
// This and default txdelay would give us a second.
if (prio == TQ_PRIO_0_HI) {
//text_color_set(DW_COLOR_DEBUG);
//dw_printf ("APRStt morse xmit delay hack...\n");
SLEEP_MS (700);
}
xmit_morse (chan, pp, wpm);
break;
case FLAVOR_DTMF:
speed = ax25_get_ssid(pp, AX25_DESTINATION);
if (speed == 0) speed = 5; // default half of maximum
if (speed > 10) speed = 10;
xmit_dtmf (chan, pp, speed);
break;
case FLAVOR_APRS_DIGI:
xmit_ax25_frames (chan, prio, pp, 1); /* 1 means don't bundle */
break;
case FLAVOR_APRS_NEW:
case FLAVOR_OTHER:
default:
xmit_ax25_frames (chan, prio, pp, 256);
break;
}
// Corresponding lock is in wait_for_clear_channel.
dw_mutex_unlock (&(audio_out_dev_mutex[ACHAN2ADEV(chan)]));
}
else {
/*
* Timeout waiting for clear channel.
* Discard the packet.
* Display with ERROR color rather than XMIT color.
*/
char stemp[1024]; /* max size needed? */
int info_len;
unsigned char *pinfo;
text_color_set(DW_COLOR_ERROR);
dw_printf ("Waited too long for clear channel. Discarding packet below.\n");
ax25_format_addrs (pp, stemp);
info_len = ax25_get_info (pp, &pinfo);
text_color_set(DW_COLOR_INFO);
dw_printf ("[%d%c] ", chan, (prio==TQ_PRIO_0_HI) ? 'H' : 'L');
dw_printf ("%s", stemp); /* stations followed by : */
ax25_safe_print ((char *)pinfo, info_len, ! ax25_is_aprs(pp));
dw_printf ("\n");
ax25_delete (pp);
} /* wait for clear channel error. */
} /* Have pp */
} /* while queue not empty */
} /* while 1 */
return 0; /* unreachable but quiet the warning. */
} /* end xmit_thread */
/*-------------------------------------------------------------------
*
* Name: xmit_ax25_frames
*
* Purpose: After we have a clear channel, and possibly waited a random time,
* we transmit one or more frames.
*
* Inputs: chan - Channel number.
*
* prio - Priority of the first frame.
* Subsequent frames could be different.
*
* pp - Packet object pointer.
* It will be deleted so caller should not try
* to reference it after this.
*
* max_bundle - Max number of frames to bundle into one transmission.
*
* Description: Turn on transmitter.
* Send flags for TXDELAY time.
* Send the first packet, given by pp.
* Possibly send more packets from either queue.
* Send flags for TXTAIL time.
* Turn off transmitter.
*
*
* How many frames in one transmission? (for APRS)
*
* Should we send multiple frames in one transmission if we
* have more than one sitting in the queue? At first I was thinking
* this would help reduce channel congestion. I don't recall seeing
* anything in the APRS specifications allowing or disallowing multiple
* frames in one transmission. I can think of some scenarios
* where it might help. I can think of some where it would
* definitely be counter productive.
*
* What to others have to say about this topic?
*
* "For what it is worth, the original APRSdos used a several second random
* generator each time any kind of packet was generated... This is to avoid
* bundling. Because bundling, though good for connected packet, is not good
* on APRS. Sometimes the digi begins digipeating the first packet in the
* bundle and steps all over the remainder of them. So best to make sure each
* packet is isolated in time from others..."
*
* Bob, WB4APR
*
*
* Version 0.9: Earlier versions always sent one frame per transmission.
* This was fine for APRS but more and more people are now
* using this as a KISS TNC for connected protocols.
* Rather than having a configuration file item,
* we try setting the maximum number automatically.
* 1 for digipeated frames, 7 for others.
*
* Version 1.4: Lift the limit. We could theoretically have a window size up to 127.
* If another section pumps out that many quickly we shouldn't
* break it up here. Empty out both queues with some exceptions.
*
* Digipeated APRS, Speech, and Morse code should have
* their own separate transmissions.
* Everything else can be bundled together.
* Different priorities can share a single transmission.
* Once we have control of the channel, we might as well keep going.
* [High] Priority frames will always go to head of the line,
*
* Version 1.5: Add full duplex option.
*
*--------------------------------------------------------------------*/
static void xmit_ax25_frames (int chan, int prio, packet_t pp, int max_bundle)
{
int pre_flags, post_flags;
int num_bits; /* Total number of bits in transmission */
/* including all flags and bit stuffing. */
int duration; /* Transmission time in milliseconds. */
int already;
int wait_more;
int numframe = 0; /* Number of frames sent during this transmission. */
/*
* These are for timing of a transmission.
* All are in usual unix time (seconds since 1/1/1970) but higher resolution
*/
double time_ptt; /* Time when PTT is turned on. */
double time_now; /* Current time. */
int nb;
/*
* Turn on transmitter.
* Start sending leading flag bytes.
*/
time_ptt = dtime_now ();
// TODO: This was written assuming bits/sec = baud.
// Does it is need to be scaled differently for PSK?
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_thread: t=%.3f, Turn on PTT now for channel %d. speed = %d\n", dtime_now()-time_ptt, chan, xmit_bits_per_sec[chan]);
#endif
ptt_set (OCTYPE_PTT, chan, 1);
// Inform data link state machine that we are now transmitting.
dlq_seize_confirm (chan); // C4.2. "This primitive indicates, to the Data-link State
// machine, that the transmission opportunity has arrived."
pre_flags = MS_TO_BITS(xmit_txdelay[chan] * 10, chan) / 8;
num_bits = hdlc_send_flags (chan, pre_flags, 0);
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_thread: t=%.3f, txdelay=%d [*10], pre_flags=%d, num_bits=%d\n", dtime_now()-time_ptt, xmit_txdelay[chan], pre_flags, num_bits);
double presleep = dtime_now();
#endif
SLEEP_MS (10); // Give data link state machine a chance to
// to stuff more frames into the transmit queue,
// in response to dlq_seize_confirm, so
// we don't run off the end too soon.
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
// How long did sleep last?
dw_printf ("xmit_thread: t=%.3f, Should be 0.010 second after the above.\n", dtime_now()-time_ptt);
double naptime = dtime_now() - presleep;
if (naptime > 0.015) {
text_color_set(DW_COLOR_ERROR);
dw_printf ("Sleep for 10 ms actually took %.3f second!\n", naptime);
}
#endif
/*
* Transmit the frame.
*/
nb = send_one_frame (chan, prio, pp);
num_bits += nb;
if (nb > 0) numframe++;
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_thread: t=%.3f, nb=%d, num_bits=%d, numframe=%d\n", dtime_now()-time_ptt, nb, num_bits, numframe);
#endif
ax25_delete (pp);
/*
* See if we can bundle additional frames into this transmission.
*/
int done = 0;
while (numframe < max_bundle && ! done) {
/*
* Peek at what is available.
* Don't remove from queue yet because it might not be eligible.
*/
prio = TQ_PRIO_1_LO;
pp = tq_peek (chan, TQ_PRIO_0_HI);
if (pp != NULL) {
prio = TQ_PRIO_0_HI;
}
else {
pp = tq_peek (chan, TQ_PRIO_1_LO);
}
if (pp != NULL) {
switch (frame_flavor(pp)) {
case FLAVOR_SPEECH:
case FLAVOR_MORSE:
case FLAVOR_DTMF:
case FLAVOR_APRS_DIGI:
default:
done = 1; // not eligible for bundling.
break;
case FLAVOR_APRS_NEW:
case FLAVOR_OTHER:
pp = tq_remove (chan, prio);
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_thread: t=%.3f, tq_remove(chan=%d, prio=%d) returned %p\n", dtime_now()-time_ptt, chan, prio, pp);
#endif
nb = send_one_frame (chan, prio, pp);
num_bits += nb;
if (nb > 0) numframe++;
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_thread: t=%.3f, nb=%d, num_bits=%d, numframe=%d\n", dtime_now()-time_ptt, nb, num_bits, numframe);
#endif
ax25_delete (pp);
break;
}
}
else {
done = 1;
}
}
/*
* Need TXTAIL because we don't know exactly when the sound is done.
*/
post_flags = MS_TO_BITS(xmit_txtail[chan] * 10, chan) / 8;
nb = hdlc_send_flags (chan, post_flags, 1);
num_bits += nb;
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_thread: t=%.3f, txtail=%d [*10], post_flags=%d, nb=%d, num_bits=%d\n", dtime_now()-time_ptt, xmit_txtail[chan], post_flags, nb, num_bits);
#endif
/*
* While demodulating is CPU intensive, generating the tones is not.
* Example: on the RPi model 1, with 50% of the CPU taken with two receive
* channels, a transmission of more than a second is generated in
* about 40 mS of elapsed real time.
*/
audio_wait(ACHAN2ADEV(chan));
/*
* Ideally we should be here just about the time when the audio is ending.
* However, the innards of "audio_wait" are not satisfactory in all cases.
*
* Calculate how long the frame(s) should take in milliseconds.
*/
duration = BITS_TO_MS(num_bits, chan);
/*
* See how long it has been since PTT was turned on.
* Wait additional time if necessary.
*/
time_now = dtime_now();
already = (int) ((time_now - time_ptt) * 1000.);
wait_more = duration - already;
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
dw_printf ("xmit_thread: t=%.3f, xmit duration=%d, %d already elapsed since PTT, wait %d more\n", dtime_now()-time_ptt, duration, already, wait_more );
#endif
if (wait_more > 0) {
SLEEP_MS(wait_more);
}
else if (wait_more < -100) {
/* If we run over by 10 mSec or so, it's nothing to worry about. */
/* However, if PTT is still on about 1/10 sec after audio */
/* should be done, something is wrong. */
/* Looks like a bug with the RPi audio system. Never an issue with Ubuntu. */
/* This runs over randomly sometimes. TODO: investigate more fully sometime. */
#ifndef __arm__
text_color_set(DW_COLOR_ERROR);
dw_printf ("Transmit timing error: PTT is on %d mSec too long.\n", -wait_more);
/* This also happens with recent Linux distributions with PipeWire audio subsystem */
/* where Wireplumber in its default setting turns off the audio output sink after */
/* several seconds of inactivity, which results in slight delay while warming up again. */
/* See: https://unix.stackexchange.com/questions/676846/how-do-i-disable-audio-sink-suspend-on-idle-using-wireplumber-in-fedora-35-so-th */
#if USE_ALSA
dw_printf ("If using PipeWIre, make sure your output sinks are not being suspended for inactivity.\n");
#endif
#endif
}
/*
* Turn off transmitter.
*/
#if DEBUG
text_color_set(DW_COLOR_DEBUG);
time_now = dtime_now();
dw_printf ("xmit_thread: t=%.3f, Turn off PTT now. Actual time on was %d mS, vs. %d desired\n", dtime_now()-time_ptt, (int) ((time_now - time_ptt) * 1000.), duration);
#endif
ptt_set (OCTYPE_PTT, chan, 0);
} /* end xmit_ax25_frames */
/*-------------------------------------------------------------------
*
* Name: send_one_frame
*
* Purpose: Send one AX.25 frame.
*
* Inputs: c - Channel number.
*
* p - Priority.
*
* pp - Packet object pointer. Caller will delete it.
*
* Returns: Number of bits transmitted.
*
* Description: Caller is responsible for activiating PTT, TXDELAY,
* deciding how many frames can be in one transmission,
* deactivating PTT.
*
*--------------------------------------------------------------------*/
static int send_one_frame (int c, int p, packet_t pp)
{
unsigned char fbuf[AX25_MAX_PACKET_LEN+2];
int flen;
char stemp[1024]; /* max size needed? */
int info_len;
unsigned char *pinfo;
int nb;
if (ax25_is_null_frame(pp)) {
// Issue 132 - We could end up in a situation where:
// Transmitter is already on.
// Application wants to send a frame.
// dl_seize_request turns into this null frame.
// It was being ignored here so the data got stuck in the queue.
// I think the solution is to send back a seize confirm here.
// It shouldn't hurt if we send it redundantly.
// Added for 1.5 beta test 4.
dlq_seize_confirm (c); // C4.2. "This primitive indicates, to the Data-link State
// machine, that the transmission opportunity has arrived."
SLEEP_MS (10); // Give data link state machine a chance to
// to stuff more frames into the transmit queue,
// in response to dlq_seize_confirm, so
// we don't run off the end too soon.
return(0);
}
char ts[100]; // optional time stamp.