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+/*
+ * Purpose: Simple audio programming example that plays morse code.
+ * Copyright (C) 4Front Technologies, 2002-2004. Released under GPLv2/CDDL.
+ *
+ * Description:
+ * This program reads stdin and plays the input to an audio device using morse
+ * code. The stdin input is supposed to be originated from a file. This
+ * program is not capable to play live keyboard input.
+ *
+ * This is a great OSS programming example because it shows how simple
+ * audio programming can be with OSS.
+ *
+ * You can use this program as a template. Just replace the
+ * while loop of the main routine by your own code.
+ *
+ * The {!nlink morse2.c} and {!nlink morse3.c} programs are more complex
+ * versions of the same program. They demonstrate how the {!nlink select}
+ * system call can be used for serving the audio device in parallel
+ * while handling terminal input.
+ *
+ * This program was tuned to be used when practising for the
+ * finnish morse code test for radio amateurs. It supports the
+ * scandinavian version of the morse code alphabet used in this test.
+ */
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <sys/soundcard.h>
+#include <math.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
+
+int charspeed = 25;
+
+int dotsize, charsize;
+int audiofd = -1;
+
+char randomlist[256];
+int nrandom;
+
+static int ncodes;
+
+double a, step;
+
+/*
+ * The genpulse() routine converts generates a single dot, dash or
+ * a pause between the symbols. this is done by generating sine wave
+ * (using cos()). It's pretty slow but works for us.
+ */
+#include "charlist.h"
+
+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;
+}
+
+/*
+ * The genmorse() routine converts an ASCII character to the
+ * equivivalent audio morse code signal.
+ */
+static int
+genmorse (short *buf, char c)
+{
+ int l = 0, i;
+ const char *s;
+
+ //printf("%c", c);
+ //fflush(stdout);
+
+ 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;
+ }
+
+ return 0;
+}
+
+/*
+ * The playchar() routine handles some special characters that are not
+ * included in the international morse aplhabet. Characters are then played by
+ * calling the genmorse() routine.
+ */
+
+static void
+playchar (char c)
+{
+ short buf[16 * BUFSZ];
+ int l;
+
+ l = 0;
+
+ if (c <= 'Z' && c >= 'A')
+ c += 32;
+
+ switch (c)
+ {
+ case '\n':
+ return;
+ break;
+ case ' ':
+ 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);
+ }
+
+ write (audiofd, buf, 2 * l);
+ if (2 * l < charsize)
+ {
+ char tmp[4 * 1024 * 1024];
+ l = charsize - 2 * l;
+ memset (tmp, 0, l);
+ write (audiofd, tmp, l);
+ }
+}
+
+int
+main (int argc, char *argv[])
+{
+ char *devname = "/dev/dsp";
+ short buf[16 * BUFSZ];
+ char line[1024];
+ int i, parm;
+ int l, speed, charspeed, wpm = 8;
+
+/*
+ * Charcter rate (CPS/WPS) handling.
+ */
+
+ if (argc > 1)
+ {
+ wpm = atoi (argv[1]);
+ if (wpm == 0)
+ wpm = 12;
+ }
+
+ if (argc > 2)
+ charspeed = atoi (argv[2]);
+
+ speed = wpm;
+ charsize = 60 * SRATE * 2 / charspeed;
+
+ printf ("Words per minute %d. Characters per minute %d\n", wpm, wpm * 5);
+ printf ("Charrate %d chars/min -> (%d samples)\n", charspeed, charsize);
+ dotsize = SRATE / speed;
+
+ ncodes = strlen (Chars);
+
+/*
+ * Open the audio device and set up the parameters.
+ */
+
+ if ((audiofd = open (devname, O_WRONLY, 0)) == -1)
+ {
+ perror (devname);
+ exit (-1);
+ }
+
+ 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);
+ }
+
+/*
+ * The setup phase is complete. After this moment we can forget that we are
+ * working on a device. The remainder of this program behaves just like
+ * it's writing to any (disk) file.
+ */
+ a = 0.0;
+
+ step = 360.0 * 600.0 / parm;
+
+ l = 0;
+ l += genpulse (&buf[l], 1, 0);
+ write (audiofd, buf, l * 2);
+
+ /* Some initial delay */
+ memset (buf, 0, 4096);
+ for (l = 0; l < 30; l++)
+ write (audiofd, buf, 4096);
+
+ while (fgets (line, sizeof (line), stdin) != NULL)
+ {
+
+ if (*line == '#')
+ continue;
+
+ for (i = 0; i < strlen (line); i++)
+ {
+ playchar (line[i]);
+ }
+ }
+
+ /* Some final delay */
+ memset (buf, 0, 4096);
+ for (l = 0; l < 20; l++)
+ write (audiofd, buf, 4096);
+
+ close (audiofd);
+
+ exit (0);
+}
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