Submitted by: phk

Add the V.21 modem emulator code written by phk from the old i4b tarball.

3 files changed, 455 insertions, 0 deletions

diff --git a/share/examples/isdn/v21/Makefile b/share/examples/isdn/v21/Makefile
new file mode 100644
index 0000000..3c49996
--- /dev/null
+++ b/share/examples/isdn/v21/Makefile
@@ -0,0 +1,12 @@
+# $FreeBSD$
+
+PROG=		v21modem
+NOMAN=		1
+LDADD=		-lutil -lm
+CFLAGS+=	-g -Wall
+
+.if !defined(BSDTYPE)
+BSDTYPE!=uname
+.endif
+
+.include <bsd.prog.mk>
diff --git a/share/examples/isdn/v21/README b/share/examples/isdn/v21/README
new file mode 100644
index 0000000..52f553c
--- /dev/null
+++ b/share/examples/isdn/v21/README
@@ -0,0 +1,50 @@
+
+                     V.21 Modem for ISDN4BSD.
+
+INTRODUCTION:
+
+The modem is implemented in software and is rather simple minded.
+
+It works with my Telebit TB2500 and Zyxel 2864I modems.
+
+There are plenty of knobs and handles which can be adjusted and I have
+no real idea what to set them to for best all-round performance.
+
+The carrier detect timer may be a bit short tempered, and this is
+probably why the dialing modem needs to be told to talk V.21 up
+front.  If this code were mode tolerant of loss of carrier auto
+negotiation might work.
+
+When you get carrier ("CONNECT 300"), you must press a key before the
+login banner gets printed.  See the comments in "input_byte" why this
+is.
+
+THE KERNEL PART:
+
+Implementes a crude "send these tones" facility, but it is enough to
+take most of the real-time worries out of doing FSK modulation in
+software.  If suitably extended, the code could also be used to
+send DTMF tones and other similar signals.
+
+INSTALLATION:
+
+The program is started from /etc/isdn/isdnd.rc:
+
+entry
+        name                    = I4BTEL
+        usrdevicename           = tel
+        usrdeviceunit           = 0
+        isdncontroller          = 0
+        isdnchannel             = -1
+        local-phone-incoming    = 2934812934
+        remote-phone-incoming   = *
+        dialin-reaction         = answer
+        answerprog              = v21modem
+        b1protocol              = raw
+        idletime-incoming       = 5
+
+
+Poul-Henning (phk@freebsd.org)
+19991212
+
+$FreeBSD$
diff --git a/share/examples/isdn/v21/v21modem.c b/share/examples/isdn/v21/v21modem.c
new file mode 100644
index 0000000..0906f35
--- /dev/null
+++ b/share/examples/isdn/v21/v21modem.c
@@ -0,0 +1,393 @@
+/*
+ * ----------------------------------------------------------------------------
+ * "THE BEER-WARE LICENSE" (Revision 42):
+ * <phk@FreeBSD.org> wrote this file.  As long as you retain this notice you
+ * can do whatever you want with this stuff. If we meet some day, and you think
+ * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
+ * ----------------------------------------------------------------------------
+ *
+ * This is a V.21 modem for ISDN4BSD.
+ *
+ * $FreeBSD$
+ */
+
+#include <string.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <err.h>
+#include <sys/ioccom.h>
+#include <errno.h>
+#include <syslog.h>
+#include <sys/types.h>
+#include <sys/ioctl.h>
+#include <termios.h>
+#include <libutil.h>
+
+#include <machine/i4b_tel_ioctl.h>
+
+static void create_session(void);
+static void input_byte(int byte, int stopbit);
+static void sample(int vol, int* tones);
+static void tonedetect(unsigned char *ptr, int count);
+static void uart(int bit);
+
+static int dcd;			/* Carrier on ? */
+static int ptyfd = -1;		/* PTY filedescriptor */
+static int telfd = -1;		/* I4BTEL filedescriptor */
+
+/*
+ * Alaw to Linear [-32767..32767] conversion
+ */
+
+static int a2l[256] = { -5504, -5248, -6016, -5760, -4480, -4224,
+-4992, -4736, -7552, -7296, -8064, -7808, -6528, -6272, -7040,
+-6784, -2752, -2624, -3008, -2880, -2240, -2112, -2496, -2368,
+-3776, -3648, -4032, -3904, -3264, -3136, -3520, -3392, -22016,
+-20992, -24064, -23040, -17920, -16896, -19968, -18944, -30208,
+-29184, -32256, -31232, -26112, -25088, -28160, -27136, -11008,
+-10496, -12032, -11520, -8960, -8448, -9984, -9472, -15104, -14592,
+-16128, -15616, -13056, -12544, -14080, -13568, -344, -328, -376,
+-360, -280, -264, -312, -296, -472, -456, -504, -488, -408, -392,
+-440, -424, -88, -72, -120, -104, -24, -8, -56, -40, -216, -200,
+-248, -232, -152, -136, -184, -168, -1376, -1312, -1504, -1440,
+-1120, -1056, -1248, -1184, -1888, -1824, -2016, -1952, -1632,
+-1568, -1760, -1696, -688, -656, -752, -720, -560, -528, -624,
+-592, -944, -912, -1008, -976, -816, -784, -880, -848, 5504, 5248,
+6016, 5760, 4480, 4224, 4992, 4736, 7552, 7296, 8064, 7808, 6528,
+6272, 7040, 6784, 2752, 2624, 3008, 2880, 2240, 2112, 2496, 2368,
+3776, 3648, 4032, 3904, 3264, 3136, 3520, 3392, 22016, 20992, 24064,
+23040, 17920, 16896, 19968, 18944, 30208, 29184, 32256, 31232,
+26112, 25088, 28160, 27136, 11008, 10496, 12032, 11520, 8960, 8448,
+9984, 9472, 15104, 14592, 16128, 15616, 13056, 12544, 14080, 13568,
+344, 328, 376, 360, 280, 264, 312, 296, 472, 456, 504, 488, 408,
+392, 440, 424, 88, 72, 120, 104, 24, 8, 56, 40, 216, 200, 248, 232,
+152, 136, 184, 168, 1376, 1312, 1504, 1440, 1120, 1056, 1248, 1184,
+1888, 1824, 2016, 1952, 1632, 1568, 1760, 1696, 688, 656, 752, 720,
+560, 528, 624, 592, 944, 912, 1008, 976, 816, 784, 880, 848 };
+
+/*
+ * A High Q Tone detector
+ */
+		
+#define NTONES	2		/* Number of tones to detect */
+#define SCALE	4096		/* Scaling factor */
+#define EXPAVG	14		/* Exponential Average factor */
+#define POLERAD	3885		/* pole_radius ^ 2 * SCALE */
+
+/* Table of "-cos(2 * PI * frequency / sample_rate) * SCALE" */
+static int p[NTONES] = {
+	-2941,			/* 980 Hz */
+	-2460			/* 1180 Hz */
+};
+
+static void
+tonedetect(unsigned char *ptr, int count)
+{
+	int i, j;
+	int y;
+	int c, d, f, n;
+	static int k[NTONES], h[NTONES];
+	static int tones[NTONES];
+	static int amplitude;
+
+
+	for (i = 0; i < count; i++) {
+		y = a2l[*ptr++];
+		if (y > 0)
+			amplitude += (y - amplitude) / EXPAVG;
+		else
+			amplitude += (-y - amplitude) / EXPAVG;
+
+		for(j = 0; j < NTONES; j++) {
+			c = (POLERAD * (y - k[j])) / SCALE;
+			d = y + c;
+			f = (p[j] * (d - h[j])) / SCALE;
+			n = y - k[j] - c;
+			if (n < 0)
+				n = -n;
+			k[j] = h[j] + f;
+			h[j] = f + d;
+			tones[j] += (n - tones[j]) / EXPAVG;
+		}
+		sample(amplitude, tones);
+	}
+}
+
+/*
+ * Taste each sample, detect (loss off) carrier, and feed uart
+ */
+
+#define NCARRIER	1000	/* Samples of carrier for detection */
+
+static void
+sample(int vol, int* tones)
+{
+	static int carrier;
+	
+	if ((tones[0] + tones[1]) > vol * 3/2) {	/* XXX */
+		if (carrier < NCARRIER)
+			carrier ++;
+	} else {
+		if (carrier > 0)
+			carrier --;
+	}
+
+	if (!dcd && carrier > NCARRIER / 2) {
+		syslog(LOG_ERR, "CARRIER ON");
+		dcd = 1;
+	} else if (dcd && carrier < NCARRIER / 2) {
+		syslog(LOG_ERR, "CARRIER OFF");
+		dcd = 0;
+	}
+
+	if (!dcd)
+		return;
+		
+	if (tones[0] > tones[1]) {
+		uart(1);
+	} else {
+		uart(0);
+	}
+}
+
+/*
+ * A UART in software
+ */
+
+#define BITCENTER	13	/* Middle of a bit: 8000/300/2 */
+static int bitsample[] = {	/* table of sampling points */
+	BITCENTER,
+	BITCENTER + 27,
+	BITCENTER + 54,
+	BITCENTER + 80,
+	BITCENTER + 107,
+	BITCENTER + 134,
+	BITCENTER + 160,
+	BITCENTER + 187,
+	BITCENTER + 214,
+	BITCENTER + 240
+};
+
+static void
+uart(int bit)
+{
+	static int n, v, j;
+
+	if (n == 0 && bit == 1)	
+		return;		/* Waiting for start bit */
+	if (n == 0) {
+		j = 0;		/* Begin start bit */
+		v = 0;
+		n++;
+	} else if (j == 0 && bit && n > bitsample[j]) {
+		n = 0;		/* Gone by middle of start bit */
+	} else if (n > bitsample[j]) {
+		j++;		/* Sample point */
+		if (j == 10) {
+			n = 0;
+			input_byte(v, bit);
+		} else {
+			v = v / 2 + 128 * bit;
+			n++;
+		}
+	} else {
+		n++;
+	}
+}
+
+/*
+ * Send a byte using kenrnel tone generation support
+ */
+
+static void
+output_byte(int val)
+{
+	struct i4b_tel_tones tt;
+	int i;
+
+	i = 0;
+	tt.frequency[i] = 1850; tt.duration[i++] = 27;
+
+	tt.frequency[i] = val &   1 ? 1650 : 1850; tt.duration[i++] = 27;
+	tt.frequency[i] = val &   2 ? 1650 : 1850; tt.duration[i++] = 26;
+	tt.frequency[i] = val &   4 ? 1650 : 1850; tt.duration[i++] = 27;
+	tt.frequency[i] = val &   8 ? 1650 : 1850; tt.duration[i++] = 27;
+	tt.frequency[i] = val &  16 ? 1650 : 1850; tt.duration[i++] = 26;
+	tt.frequency[i] = val &  32 ? 1650 : 1850; tt.duration[i++] = 27;
+	tt.frequency[i] = val &  64 ? 1650 : 1850; tt.duration[i++] = 27;
+	tt.frequency[i] = val & 128 ? 1650 : 1850; tt.duration[i++] = 26;
+
+	tt.frequency[i] = 1650; tt.duration[i++] = 27;
+	tt.frequency[i] = 1650; tt.duration[i++] = 0;
+
+	i = ioctl(telfd, I4B_TEL_TONES, &tt);
+	if (i != 0 && errno != EAGAIN) {
+		syslog(LOG_ERR, "%d: *** %d/%d ***", __LINE__, i, errno);
+		exit(0);
+	}
+}
+
+/*
+ * Create Session
+ */
+
+static void
+create_session(void)
+{
+	int i;
+	char buf[100];
+
+	i = forkpty(&ptyfd, buf, 0, 0);
+	if (i == 0) {
+		execl("/usr/libexec/getty", "getty", "std.300", "-", NULL);
+		syslog(LOG_ERR, "exec getty %d", errno);
+		exit(2);
+	} else if (i < 0) {
+		syslog(LOG_ERR, "forkpty failed %d", errno);
+		exit(2);
+	}
+	syslog(LOG_ERR, "pty %s", buf);
+}
+
+static void 
+input_byte(int byte, int stopbit)
+{
+	u_char c;
+	int i;
+	static int first;
+	static u_char buf[80];
+
+	if (!stopbit)
+		return;
+	c = byte;
+	/*
+	 * I have no idea why, but my TB2500 modem sends a sequence of
+	 * 28 bytes after carrier is established at the link level, but
+	 * before it is acceptted at the logical level.
+	 *
+	 *  [16100214010201060100000000ff0201020301080402400010034510]
+	 *
+	 * Unfortunately this contains a ^D which kills getty.
+	 * The following code swallows this sequence, assuming that it
+	 * is always the same length and always start with 0x16.
+	 *
+	 */
+	if (first == 0 && c == 0x16) {
+		sprintf(buf, "%02x", c);
+		first = 27;
+		return;
+	} else if (first == 0) {
+		first = -1;
+		dcd = 2;
+		return;
+	}
+	if (first > 0) {
+		sprintf(buf + strlen(buf), "%02x", c);
+		first--;
+		if (!first) {
+			syslog(LOG_NOTICE, "Got magic [%s]", buf);
+			*buf = 0;
+		}
+		return;
+	}
+	if (ptyfd != -1 && dcd) {
+		i = write(ptyfd, &c, 1);
+		if (i != 1 && errno != EAGAIN) {
+		syslog(LOG_ERR, "%d: *** %d/%d ***", __LINE__, i, errno);
+			exit(0);
+		}
+	}
+}
+
+int
+main(int argc, char **argv)
+{
+	char *device = "/dev/tel0";
+	u_char ibuf[2048];
+	int ii, io;
+	int i, maxfd;
+	struct i4b_tel_tones tt;
+	fd_set rfd, wfd, efd;
+
+	openlog("v21modem", LOG_PID, LOG_DAEMON);
+	/* Find our device name */
+	for (i = 0; i < argc; i++)
+		if (!strcmp(argv[i], "-D"))
+			device = argv[i + 1];
+	telfd = open(device, O_RDWR, 0);
+	if (telfd < 0) {
+		syslog(LOG_ERR, "open %s: %m", device);
+		exit (0);
+	}
+	syslog(LOG_NOTICE, "Running on %s", device);
+
+	/* Output V.25 tone and carrier */
+	i = 0;
+	tt.frequency[i] =    0; tt.duration[i++] = 1000;
+	tt.frequency[i] = 2100; tt.duration[i++] = 2*8000;
+	tt.frequency[i] =    0; tt.duration[i++] = 400;
+	tt.frequency[i] = 1650; tt.duration[i++] = 1;
+	tt.frequency[i] = 1650; tt.duration[i++] = 0;
+	tt.frequency[i] =    0; tt.duration[i++] = 0;
+	i = ioctl(telfd, I4B_TEL_TONES, &tt);
+	if (i < 0) {
+		syslog(LOG_ERR, "hangup");
+		exit(0);
+	}
+
+	create_session();
+
+	/* Wait for carrier */
+	do {
+		ii = read(telfd, ibuf, sizeof ibuf);
+		tonedetect(ibuf, ii);
+	} while (ii > 0 && dcd != 2);
+	if (ii < 0) {
+		syslog(LOG_ERR, "hangup");
+		exit(0);
+	}
+
+	maxfd = ptyfd;
+	if (telfd > maxfd)
+		maxfd = telfd;
+	maxfd += 1;
+	do {
+		FD_ZERO(&rfd);
+		FD_SET(telfd, &rfd);
+		FD_SET(ptyfd, &rfd);
+		FD_ZERO(&wfd);
+		FD_ZERO(&efd);
+		FD_SET(telfd, &efd);
+		FD_SET(ptyfd, &efd);
+		i = select(maxfd, &rfd, &wfd, &efd, NULL);
+		if (FD_ISSET(telfd, &rfd)) {
+			ii = read(telfd, ibuf, sizeof ibuf);
+			if (ii > 0)
+				tonedetect(ibuf, ii);
+			else
+				syslog(LOG_ERR, "hangup");
+		}
+		if (FD_ISSET(ptyfd, &rfd)) {
+			io = read(ptyfd, ibuf, 1);
+			if (io == 1)
+				output_byte(*ibuf);
+			else if (io == 0) {
+				syslog(LOG_ERR, "Session EOF");
+				exit(0);
+			}
+			
+		}
+		if (FD_ISSET(telfd, &efd)) {
+			syslog(LOG_ERR, "Exception TELFD");
+			exit (0);
+		}
+		if (FD_ISSET(ptyfd, &efd)) {
+			syslog(LOG_ERR, "Exception PTYFD");
+			exit (0);
+		}
+	} while (dcd);
+	syslog(LOG_ERR, "Carrier Lost");
+	exit(0);
+}