Added support for gen_packets.

**** NOTE THAN THE MARK AND SPACE FREQUENCIES ARE BACKWARDS in gen_tone.c.

Lines 228-229 correctly set f1_change_per_sample to the MARK frequency and
f2_change_per_sample the space frequency.

Line 383, however, sends MARK on 0 and SPACE on 1:

tone_phase[chan] += dat ? f2_change_per_sample[chan] : f1_change_per_sample[chan];

As such, you have to generate packets like this:

	gen_packets -e R -m 1800 -s 1200 -o test.wav eotd.data

EOTD input to the program consists of lines of 8 byte packets in HCB+ATAD
format; i.e. the format that direwolf appends to the decoded packet.

Ex: 81 b0 32 fb 31 23 73 8f

A new option has been added to atest: -e type. That enables EOTD generation and
the 'type' signifies 'R'ear to front or 'F'ront to rear decoding.

Using "atest -B EOTD test.wav" the above packet decodes to:

DECODED[1] 0:00.123 EOTD audio level = 49(30/31)
[0] EOTD>APDW16:{DRREAR>FRONT:ts=2022-04-07T10:02:00.350,chain=ONLY,block=BASIC,devbat=OK,msgid=ONEWAY,unit_addr=18151,brake_status=GO(49 psig),disc_bits=f6,valve=OPERATIONAL,confirm=UPDATE,disc_bit_1=1,motion=STOPPED/NOT_MONITORED,light_batt=OK/NOT_MONITORED,light=ON,hex=81 b0 32 fb 31 23 73 8f

src/CMakeLists.txt

@@ -278,6 +278,7 @@ list(APPEND gen_packets_SOURCES
   dtmf.c
   textcolor.c
   dsp.c
+  eotd_send.c
   )
 
 add_executable(gen_packets

src/bchapply.c

@@ -63,7 +63,7 @@ printf("data_len=%d, crc_len=%d\n", data_len, crc_len);
 //
 //	THIS IS THE LSB-FIRST VERSION
 //
-fprintf(stderr, "Enter HCB+ATAD _WITH_ the parity bit intact.\n");
+fprintf(stderr, "Enter HCB+ATAD _WITH_ the parity bit intact and XOR already applied.\n");
 	while (1) {
 		for (int i = 0; i < 8; i++) {
 			int temp;

src/eotd_send.c

@@ -0,0 +1,102 @@
+#include "direwolf.h"
+
+#include <stdio.h>
+
+#include "eotd_send.h"
+#include "audio.h"
+#include "gen_tone.h"
+#include "eotd_defs.h"
+
+#define EOTD_SILENCE_SAMPLES 1000
+//#define EOTD_SEND_DEBUG
+
+static int eotd_fs[] = {1, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0};
+static int hotd_fs[] = {1, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1 };
+
+void my_tone_gen_put_bit (int chan, int bit) {
+
+#ifdef EOTD_SEND_DEBUG
+	printf("mytone bit %d\n", bit);
+#endif
+	tone_gen_put_bit (chan, bit);
+}
+
+void my_gen_tone_put_sample (int chan, int a, int sam) {
+
+#ifdef EOTD_SEND_DEBUG
+	printf("mysilence sample %d\n", sam);
+#endif
+	gen_tone_put_sample (chan, a, sam);
+}
+
+void send_preamble(int chan, char type) {
+	int bit = 0;
+	int preamble_count;
+	int fs_count;
+        int *fs;
+
+	if (type == EOTD_TYPE_R2F) {
+	  bit = 0;
+	  preamble_count = 69;
+	  fs_count = sizeof(eotd_fs) / sizeof(int);
+	  fs = eotd_fs;
+        } else {
+          preamble_count = 456;
+	  fs_count = sizeof(hotd_fs) / sizeof(int);
+	  fs = hotd_fs;
+	}
+
+	for (int i = 0; i < preamble_count; i++) {
+	  my_tone_gen_put_bit (chan, bit);
+	  bit ^= 1;
+	}
+
+#ifdef EOTD_SEND_DEBUG
+	printf("end-of-preamble\n");
+#endif
+	// send FS
+	for (int i = 0; i < fs_count; i++) {
+	  my_tone_gen_put_bit (chan, fs[i]);
+	}
+
+#ifdef EOTD_SEND_DEBUG
+	printf("end-of-fs\n");
+#endif
+}
+
+void send_silence(int chan) {
+	int a = ACHAN2ADEV(chan);
+
+	for (int i = 0; i < EOTD_SILENCE_SAMPLES; i++) {
+	  my_gen_tone_put_sample (chan, a, 0);
+	}
+}
+
+int eotd_send_block (int chan, char *str, char type) {
+
+	unsigned int b[EOTD_LENGTH];
+
+        int status = sscanf(str, "%x %x %x %x %x %x %x %x", b, b+1, b+2, b+3, b+4, b+5, b+6, b+7);
+        if (status != EOTD_LENGTH) {
+                    fprintf(stderr, "Error: expected 8, read %d", status);
+		    return -1;
+        }
+
+	send_preamble(chan, type);
+
+	for (int i = 7; i >= 0; i--) {
+	    int byte = b[i];	// Copy this non-destructively so we can repeat it later, per spec.
+	    for (int j = 0; j < 8; j++) {
+	      int bit = byte & 0x01;
+	      byte >>= 1;
+	      my_tone_gen_put_bit (chan, bit);
+	  }
+        }
+
+#ifdef EOTD_SEND_DEBUG
+	printf("end-of-data\n");
+#endif
+	send_silence(chan);
+
+	return 0;
+}

src/eotd_send.h

@@ -0,0 +1,6 @@
+#ifndef __EOTD_SEND_H
+#define __EOTD_SEND_H
+
+int eotd_send_block (int chan, char *str, char type);
+
+#endif

src/gen_packets.c

@@ -76,6 +76,8 @@
 #include "morse.h"
 #include "dtmf.h"
 #include "fx25.h"
+#include "eotd_send.h"
+#include "eotd_defs.h"
 
 
 /* Own random number generator so we can get */
@@ -97,6 +99,10 @@ static int audio_file_close (void);
 static int g_add_noise = 0;
 static float g_noise_level = 0;
 static int g_morse_wpm = 0;		/* Send morse code at this speed. */
+static int g_eotd_type = 0;
+
+static int byte_count;			/* Number of data bytes written to file. */
+					/* Will be written to header when file is closed. */
 
 
 static struct audio_s modem;
@@ -115,6 +121,11 @@ static void send_packet (char *str)
 
 	  morse_send (0, str, g_morse_wpm, 100, 100);
 	}
+        else if (g_eotd_type > 0) {
+	  for (c=0; c<modem.adev[0].num_channels; c++) {
+	    eotd_send_block (c, str, g_eotd_type);
+	  }
+        }
 	else {
 	  pp = ax25_from_text (str, 1);
 	  if (pp == NULL) {
@@ -227,7 +238,7 @@ int main(int argc, char **argv)
 
 	  /* ':' following option character means arg is required. */
 
-          c = getopt_long(argc, argv, "gjJm:s:a:b:B:r:n:N:o:z:82M:X:",
+          c = getopt_long(argc, argv, "gjJm:s:a:b:B:r:n:N:o:z:82M:X:e:",
                         long_options, &option_index);
           if (c == -1)
             break;
@@ -462,6 +473,15 @@ int main(int argc, char **argv)
               usage (argv);
               break;
 
+            case 'e':
+	      g_eotd_type = optarg[0];
+	      if (g_eotd_type != EOTD_TYPE_F2R && g_eotd_type != EOTD_TYPE_R2F) {
+                text_color_set(DW_COLOR_ERROR); 
+                dw_printf ("EOTD type must be %c or %c\n", EOTD_TYPE_F2R, EOTD_TYPE_R2F);
+	        exit(EXIT_FAILURE);
+	      }
+              break;
+
             default:
 
               /* Should not be here. */
@@ -757,9 +777,6 @@ static FILE *out_fp = NULL;
 
 static struct wav_header header;
 
-static int byte_count;			/* Number of data bytes written to file. */
-					/* Will be written to header when file is closed. */
-
 
 static int audio_file_open (char *fname, struct audio_s *pa)
 {

src/hdlc_rec.c

@@ -50,6 +50,7 @@
 #include "bch.h"
 #include "eotd_defs.h"
 
+//#define EOTD_DEBUG
 
 //#define TEST 1				/* Define for unit testing. */
 
@@ -473,11 +474,20 @@ int is_eotd_valid(struct hdlc_state_s *H) {
 
 	// Note: bits are changed in-place.
 	int corrected = apply_bch(temp_bch, bits + 1);
+
 	// Put back in HCB+ATAD format
 	rotate_bits(bits + 1, temp_bits, crc_len);
 	memcpy(bits + 1, temp_bits, crc_len * sizeof(int));
 	bits_to_bytes(bits, H->frame_buf, 64);
 
+	// Put the XOR-ed bits back.
+	if (H->eotd_type == EOTD_TYPE_R2F) {
+		// The HCB needs to be XOR'ed with a special constant.
+		for (int i = 0; i < sizeof(r2f_mask); i++) {
+			H->frame_buf[i] ^= r2f_mask[i];
+		}
+	}
+
 	return corrected;
 }
 
@@ -515,7 +525,8 @@ static void eotd_rec_bit (int chan, int subchan, int slice, int raw, int future_
 	H = &hdlc_state[chan][subchan][slice];
 
 #ifdef EOTD_DEBUG
-dw_printf("chan=%d subchan=%d slice=%d raw=%d\n", chan, subchan, slice, raw);
+// dw_printf("chan=%d subchan=%d slice=%d raw=%d\n", chan, subchan, slice, raw);
+dw_printf("%d ", raw);
 #endif
 	  //dw_printf ("slice %d = %d\n", slice, raw);
 
@@ -565,7 +576,12 @@ for (int ii=0; ii < EOTD_LENGTH; ii++) {dw_printf("%02x ", H->frame_buf[ii]); }
 	  if (is_eotd_valid(H) >= 0) {
 	  	alevel_t alevel = demod_get_audio_level (chan, subchan);
 	  	multi_modem_process_rec_frame (chan, subchan, slice, H->frame_buf, H->frame_len, alevel, 0, 0);
-	  }
+	  } else {
+#ifdef EOTD_DEBUG
+print_bytes("BCH failed for packet (type byte appended) ", H->frame_buf, H->frame_len);
+#endif
+
+}
 
 	  H->eotd_acc = 0;
 	  H->eotd_gathering = 0;