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Copyright (C) 4Front Technologies, 2002-2004. Released under GPLv2/CDDL.
This program is a significantly more complicated version of morse.c. It uses the select system call to be able to handle keyboard input and audio output at the same time. It shows how to prevent output underruns by writing silent samples to the audio device when there is no "payload" signal to play.
What the program does is playing randomly selected morse symbols (based on the command line options). It then waits until the users hits a key. If the input character matches the morse output then the program continues by playing another morse character. If there was an error then the next character is repeated. The Esc key is used to stop the program.
Parts on this program are common with morse.c and commented only there.
The morse3.c program is a slightly different version of this one.
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <sys/soundcard.h>
#include <math.h>
#include <termios.h>
#include <signal.h>
#include <sys/time.h>
#include <sys/types.h>
#define BUFSZ (16*1024)
#define SRATE 48000
#define ATTACK 100
#define CHARDELAY 3
char randomlist[65536];
int nrandom = 0;
int done = 0;
int chars_to_play = 100;
int dotsize;
int audiofd = -1;
static int ncodes;
static int playc;
static int terminal_fd = 0;
static struct termios ti, saved_ti;
static int totalchars = 0, totalerrors = 0, errors = 0;
static time_t t0;
double a, step;
#include "charlist.h"
static void
terminate (int sig)
{
time_t t;
t = time (0) - t0;
if (terminal_fd == -1)
return;
if (tcsetattr (terminal_fd, TCSAFLUSH, &saved_ti) == -1)
{
perror ("tcgetattr");
exit (-1);
}
printf ("\n\nTotal characters: %d\n", totalchars);
printf ("Errors: %d\n", totalerrors);
printf ("Elapsed time: %d seconds\n", t);
if (errors == 0) totalchars--;
if (totalchars <= totalerrors) totalchars = 0;
else
{
totalchars -= totalerrors;
totalchars += totalchars / 5;
}
printf ("Characters per minute: %g\n",
t > 0?(float) totalchars / (float) t * 60.0:0);
exit (sig);
}
static int
genpulse (short *buf, int w, int state)
{
int i, l;
a = 0.0;
l = w * dotsize;
for (i = 0; i < ATTACK; i++)
{
double tmp = 0x7fff * cos (a * M_PI / 180.0);
tmp *= (double) (i) / (double) ATTACK;
*buf++ = (int) tmp *state;
a += step;
if (a > 360.0)
a -= 360.0;
}
for (i = ATTACK; i < l - ATTACK; i++)
{
double tmp = 0x7fff * cos (a * M_PI / 180.0);
*buf++ = (int) tmp *state;
a += step;
if (a > 360.0)
a -= 360.0;
}
for (i = l - ATTACK; i < l; i++)
{
double tmp = 0x7fff * cos (a * M_PI / 180.0);
tmp *= (double) (l - i) / (double) ATTACK;
*buf++ = (int) tmp *state;
a += step;
if (a > 360.0)
a -= 360.0;
}
return l;
}
static void
playerror (void)
{
short buffer[65536], *buf = buffer;
int i, l;
a = 0.0;
l = dotsize;
for (i = 0; i < ATTACK; i++)
{
double tmp = 0x7fff * cos (a * M_PI / 180.0);
tmp *= (double) (i) / (double) ATTACK;
*buf++ = (int) tmp;
a += step * 2.0;
if (a > 360.0)
a -= 360.0;
}
for (i = ATTACK; i < l - ATTACK; i++)
{
double tmp = 0x7fff * cos (a * M_PI / 180.0);
*buf++ = (int) tmp;
a += step * 2.0;
if (a > 360.0)
a -= 360.0;
}
for (i = l - ATTACK; i < l; i++)
{
double tmp = 0x7fff * cos (a * M_PI / 180.0);
tmp *= (double) (l - i) / (double) ATTACK;
*buf++ = (int) tmp;
a += step * 2.0;
if (a > 360.0)
a -= 360.0;
}
write (audiofd, buffer, 2 * l);
}
static int
genmorse (short *buf, char c)
{
int l = 0, i;
const char *s;
if (c == ' ')
return genpulse (buf, 4, 0);
for (i = 0; i < ncodes; i++)
if (Chars[i] == c)
{
s = Codes[i];
while (*s)
{
if (*s++ == '.')
l += genpulse (&buf[l], 1, 1);
else
l += genpulse (&buf[l], 3, 1);
l += genpulse (&buf[l], 1, 0);
}
l += genpulse (&buf[l], CHARDELAY, 0);
return l;
}
printf ("<?>");
fflush (stdout);
return 0;
}
static void
playchar (char c)
{
short buf[16 * BUFSZ];
int l;
l = 0;
if (c <= 'Z' && c >= 'A')
c += 32;
switch (c)
{
case ' ':
case '\n':
case '\t':
l = genmorse (buf, ' ');
break;
case '\r':
break;
case 'Å':
l = genmorse (buf, 'å');
break;
case 'Ä':
l = genmorse (buf, 'ä');
break;
case 'Ö':
l = genmorse (buf, 'ö');
break;
case 'Ü':
l = genmorse (buf, 'ü');
break;
default:
l = genmorse (buf, c);
}
Next write whatever we have in the buffer. Note that this write will block but that time is at most the time required to play one morse code character. There is no need to avoid blocking because it doesn't cause any annoying delays.
This is often the case with audio application. While many programmers think blocking is evil it's actually programmer's best friend.
if (write (audiofd, buf, 2 * l) != 2 * l)
{
perror ("write audio");
terminate (15);
}
}
The randomplay() routine picks a character from the list of characters selected for practice.
static void
randomplay (void)
{
int old = playc;
if (totalchars == chars_to_play)
{
done = 1;
return;
}
// while (playc==old)
{
int i, x, tmp;
x = random () % nrandom;
playc = randomlist[x];
#if 1
if (x != nrandom - 1)
{
tmp = randomlist[x];
for (i = x; i < nrandom - 1; i++)
randomlist[i] = randomlist[i + 1];
randomlist[nrandom - 1] = tmp;
}
#endif
}
playchar (playc);
totalchars++;
}
static int
findcode (char c)
{
int i;
for (i = 0; i < ncodes; i++)
if (Chars[i] == c)
return i;
return 0;
}
int
main (int argc, char *argv[])
{
char *devname = "/dev/dsp";
short buf[32 * BUFSZ];
char line[1024];
int i, parm;
int l, speed, wpm = 12;
fd_set readfds, writefds;
if (argc > 1)
devname = argv[1];
if (argc > 2)
{
wpm = atoi (argv[2]);
if (wpm == 0)
wpm = 12;
}
ncodes = strlen (Chars);
srandom (time (0));
if (argc > 3)
{
for (i = 3; i < argc; i++)
parse_charlist (argv[i]);
}
else
{
strcpy (randomlist, Chars);
nrandom = strlen (randomlist);
}
if (nrandom < 2)
{
printf ("Bad character list\n");
exit (-1);
}
randomlist[nrandom] = 0;
printf ("Practicing codes: %s\n", randomlist);
for (i = 0; i <= nrandom; i += 4)
{
int j, k;
char line[256], tmp[20];
memset (line, ' ', 80), line[78] = 0;
for (j = 0; j < 4; j++)
if (i + j <= nrandom)
{
int ix;
ix = findcode (randomlist[i + j]);
sprintf (tmp, "%c %s", randomlist[i + j], Codes[ix]);
for (k = 0; k < strlen (tmp); k++)
line[j * 20 + k] = tmp[k];
}
printf ("%s\n", line);
}
speed = wpm;
printf ("Words per minute %d. Characters per minute %d\n", wpm, wpm * 5);
dotsize = SRATE / speed;
if ((audiofd = open (devname, O_WRONLY, 0)) == -1)
{
perror (devname);
exit (-1);
}
parm = 0x0003000a;
ioctl (audiofd, SNDCTL_DSP_SETFRAGMENT, &parm);
parm = AFMT_S16_LE;
if (ioctl (audiofd, SNDCTL_DSP_SETFMT, &parm) == -1)
{
perror ("SETFMT");
close (audiofd);
exit (-1);
}
if (parm != AFMT_S16_LE)
{
printf
("Error: 32/24 bit sample format is not supported by the device\n");
printf ("%08x/%08x\n", parm, AFMT_S16_LE);
close (audiofd);
exit (-1);
}
parm = SRATE;
if (ioctl (audiofd, SNDCTL_DSP_SPEED, &parm) == -1)
{
perror ("SPEED");
close (audiofd);
exit (-1);
}
if (parm != SRATE)
{
printf
("Error: %d Hz sampling rate is not supported by the device (%d)\n",
SRATE, parm);
close (audiofd);
exit (-1);
}
if (tcgetattr (terminal_fd, &saved_ti) == -1)
{
perror ("tcgetattr");
exit (-1);
}
signal (SIGINT, terminate);
Set up the terminal (stdin) for single character input.
if (tcgetattr (terminal_fd, &ti) == -1)
{
perror ("tcgetattr");
exit (-1);
}
ti.c_lflag &= ~(ECHO | ICANON | IEXTEN | ISIG);
ti.c_iflag &= ~(BRKINT | ICRNL | INPCK | ISTRIP | IXON);
ti.c_cflag &= ~(CSIZE | PARENB);
ti.c_cflag |= CS8;
ti.c_oflag &= ~(OPOST);
ti.c_cc[VMIN] = 1;
ti.c_cc[VTIME] = 1;
if (tcsetattr (terminal_fd, TCSAFLUSH, &ti) == -1)
{
perror ("tcgetattr");
exit (-1);
}
a = 0.0;
Play some "extra" audio data to delay the startup. This just gives some extra time to the user to prepare before we start.
step = 360.0 * 600.0 / parm;
l = 0;
l += genpulse (&buf[l], 1, 0);
write (audiofd, buf, l * 2);
memset (buf, 0, 4096);
for (i = 0; i < 2; i++)
write (audiofd, buf, 4096);
The actual playback starts here
randomplay ();
t0 = time (0);
while (!done)
{
int n;
Set up select for output events on the audio device and input events on the keyboard.
FD_ZERO (&readfds);
FD_ZERO (&writefds);
FD_SET (audiofd, &writefds);
FD_SET (0, &readfds);
Call select with no timeouts
if ((n = select (audiofd + 1, &readfds, &writefds, NULL, NULL)) == -1)
{
perror ("select");
exit (-1);
}
if (n == 0)
continue;
if (FD_ISSET (0, &readfds)) /* 0 means stdin */
{
Handling of keyboard input. Check if the answer was right.
if (read (0, line, 1) == 1)
{
if (*line == 27) /* ESC */
terminate (SIGINT);
if ((unsigned char) *line != (unsigned char) playc)
{
int x;
totalerrors++;
chars_to_play += 4;
randomlist[nrandom++] = playc;
randomlist[nrandom++] = playc;
for (x = 0; x < nrandom; x++)
if (randomlist[x] == *line)
{
randomlist[nrandom++] = *line;
break;
}
playerror ();
if (++errors > 3)
{
printf ("It is '%c' not '%c'\r\n", playc, *line);
fflush (stdout);
}
playchar (playc);
}
else
{
errors = 0;
randomplay ();
}
}
}
if (FD_ISSET (audiofd, &writefds))
{
The audio device is ready to accept more data. Keep the device happy by writing some silent samples to it.
Note that the real "playload" signal will be played by the playchar() routine.
memset (buf, 0, 1024);
write (audiofd, buf, 1024);
}
}
Everything done. Restore the teminal settings and exit.
terminate (15); close (audiofd); exit (0); }