FX.25 enable value 1 now selects appropriate tag for frame length.

wb2osz · wb2osz · commit 909b703b7e2c · 2020-06-22T17:04:03.000-04:00
diff --git a/src/fx25_init.c b/src/fx25_init.c
@@ -130,6 +130,9 @@ static const struct correlation_tag_s tags[16] = {
 				// 12 got many false matches with random noise.
 				// Even 8 might be too high.  We see 2 or 4 bit errors here
 				// at the point where decoding the block is very improbable.
+				// After 2 months of continuous operation as a digipeater/iGate,
+				// no false triggers were observed.  So 8 doesn't seem to be too
+				// high for 1200 bps.  No study has been done for 9600 bps.
 
 // Given a 64 bit correlation tag value, find acceptable match in table.
 // Return index into table or -1 for no match.
@@ -215,14 +218,14 @@ void fx25_init ( int debug_level )
 	  assert (tags[j].n_block_rs == FX25_BLOCK_SIZE);
 	}
 
-	assert (fx25_pick_mode (1, 239) == 1);
-	assert (fx25_pick_mode (1, 240) == -1);
+	assert (fx25_pick_mode (100+1, 239) == 1);
+	assert (fx25_pick_mode (100+1, 240) == -1);
 
-	assert (fx25_pick_mode (5, 223) == 5);
-	assert (fx25_pick_mode (5, 224) == -1);
+	assert (fx25_pick_mode (100+5, 223) == 5);
+	assert (fx25_pick_mode (100+5, 224) == -1);
 
-	assert (fx25_pick_mode (9, 191) == 9);
-	assert (fx25_pick_mode (9, 192) == -1);
+	assert (fx25_pick_mode (100+9, 191) == 9);
+	assert (fx25_pick_mode (100+9, 192) == -1);
 
 	assert (fx25_pick_mode (16, 32) == 4);
 	assert (fx25_pick_mode (16, 64) == 3);
@@ -241,6 +244,16 @@ void fx25_init ( int debug_level )
 	assert (fx25_pick_mode (64, 191) == 9);
 	assert (fx25_pick_mode (64, 192) == -1);
 
+	assert (fx25_pick_mode (1, 32) == 4);
+	assert (fx25_pick_mode (1, 33) == 3);
+	assert (fx25_pick_mode (1, 64) == 3);
+	assert (fx25_pick_mode (1, 65) == 6);
+	assert (fx25_pick_mode (1, 128) == 6);
+	assert (fx25_pick_mode (1, 191) == 9);
+	assert (fx25_pick_mode (1, 223) == 5);
+	assert (fx25_pick_mode (1, 239) == 1);
+	assert (fx25_pick_mode (1, 240) == -1);
+
 }  // fx25_init
 
 
@@ -290,37 +303,43 @@ int fx25_get_debug (void)
  * Purpose:	Pick suitable transmission format based on user preference
  *		and size of data part required.
  *
- * Inputs:	fx_mode	- Normally, this would be 16, 32, or 64 for the desired number
- *			  of check bytes.  The shortest format, adequate for the 
- *			  required data length will be picked automatically.
- *			  0x01 thru 0x0b may also be specified for a specific format
- *			  but this is expected to be mostly for testing, not normal
- *			  operation.
+ * Inputs:	fx_mode	- 0 = none.
+ *			1 = pick a tag automatically.
+ *			16, 32, 64 = use this many check bytes.
+ *			100 + n = use tag n.
+ *
+ *			0 and 1 would be the most common.
+ *			Others are mostly for testing.
  *
  *		dlen - 	Required size for transmitted "data" part, in bytes.
  *			This includes the AX.25 frame with bit stuffing and a flag
  *			pattern on each end.
  *
  * Returns:	Correlation tag number in range of CTAG_MIN thru CTAG_MAX.
  *		-1 is returned for failure.
- *
- * Future:	Might be more accomodating.
- *		For example, if 64 check bytes were specified for 200 data bytes,
- *		we might automatically drop it down to 32 check bytes, print a 
- *		warning and continue.  Keep it simple at first.  Fine tune later.
+ *		The caller should fall back to using plain old AX.25.
  *
  *--------------------------------------------------------------*/
 
 int fx25_pick_mode (int fx_mode, int dlen)
 {
-	if (fx_mode >= CTAG_MIN && fx_mode <= CTAG_MAX) {
-	  if (dlen <= fx25_get_k_data_radio(fx_mode)) {
-	    return (fx_mode);
+	if (fx_mode <= 0) return (-1);
+
+// Specify a specific tag by adding 100 to the number.
+// Fails if data won't fit.
+
+	if (fx_mode - 100 >= CTAG_MIN && fx_mode - 100 <= CTAG_MAX) {
+	  if (dlen <= fx25_get_k_data_radio(fx_mode - 100)) {
+	    return (fx_mode - 100);
 	  }
 	  else {
 	    return (-1);	// Assuming caller prints failure message.
 	  }
 	}
+
+// Specify number of check bytes.
+// Pick the shortest one that can handle the required data length.
+
 	else if (fx_mode == 16 || fx_mode == 32 || fx_mode == 64) {
 	  for (int k = CTAG_MAX; k >= CTAG_MIN; k--) {
 	    if (fx_mode == fx25_get_nroots(k) && dlen <= fx25_get_k_data_radio(k)) {
@@ -329,11 +348,41 @@ int fx25_pick_mode (int fx_mode, int dlen)
 	  }
 	  return (-1);
 	}
-	else {
-	  text_color_set(DW_COLOR_ERROR);
-	  dw_printf("FX.25: Transmission format %d must be 0x00 thru 0x0b, 16, 32, or 64.\n", fx_mode);
-	  exit(EXIT_FAILURE);
+
+// For any other number, [[ or if the preference was not possible, ?? ]]
+// try to come up with something reasonable.  For shorter frames,
+// use smaller overhead.  For longer frames, where an error is
+// more probable, use more check bytes.  When the data gets even
+// larger, check bytes must be reduced to fit in block size.
+// When all else fails, fall back to normal AX.25.
+// Some of this is from observing UZ7HO Soundmodem behavior.
+//
+//	Tag 	Data 	Check 	Max Num
+//	Number	Bytes	Bytes	Repaired
+//	------	-----	-----	-----
+//	0x04	32	16	8
+//	0x03	64	16	8
+//	0x06	128	32	16
+//	0x09	191	64	32
+//	0x05	223	32	16
+//	0x01	239	16	8
+//	none	larger		
+//
+// The PRUG FX.25 TNC has additional modes that will handle larger frames
+// by using multiple RS blocks.  This is a future possibility but needs
+// to be coordinated with other FX.25 developers so we maintain compatibility.
+
+	static const int prefer[6] = { 0x04, 0x03, 0x06, 0x09, 0x05, 0x01 };
+	for (int k = 0; k < 6; k++) {
+	  int m = prefer[k];
+	  if (dlen <= fx25_get_k_data_radio(m)) {
+	    return (m);
+	  }
 	}
+	return (-1);
+
+// TODO: revisit error messages, produced by caller, when this returns -1.
+
 }
 
 
diff --git a/src/fx25_rec.c b/src/fx25_rec.c
@@ -63,7 +63,7 @@ static struct fx_context_s *fx_context[MAX_CHANS][MAX_SUBCHANS][MAX_SLICERS];
 
 static void process_rs_block (int chan, int subchan, int slice, struct fx_context_s *F);
 
-static int my_unstuff (unsigned char * restrict pin, int ilen, unsigned char * restrict frame_buf);
+static int my_unstuff (int chan, int subchan, int slice, unsigned char * restrict pin, int ilen, unsigned char * restrict frame_buf);
 
 //#define FXTEST 1	// Define for standalone test application.
 			// It expects to find files fx01.dat, fx02.dat, ..., fx0b.dat/
@@ -182,7 +182,8 @@ void fx25_rec_bit (int chan, int subchan, int slice, int dbit)
 
 	      if (fx25_get_debug() >= 2) {
 	        text_color_set(DW_COLOR_INFO);
-	        dw_printf ("FX.25: Matched correlation tag 0x%02x with %d bit errors.  Expecting %d data & %d check bytes.\n",
+	        dw_printf ("FX.25[%d.%d]: Matched correlation tag 0x%02x with %d bit errors.  Expecting %d data & %d check bytes.\n",
+			chan, slice,	// ideally subchan too only if applicable
 			c,
 			__builtin_popcountll(F->accum ^ fx25_get_ctag_value(c)),
 			F->k_data_radio, F->nroots);
@@ -308,7 +309,7 @@ static void process_rs_block (int chan, int subchan, int slice, struct fx_contex
 {
 	if (fx25_get_debug() >= 3) {
 	  text_color_set(DW_COLOR_DEBUG);
-	  dw_printf ("FX.25: Received RS codeblock.\n");
+	  dw_printf ("FX.25[%d.%d]: Received RS codeblock.\n", chan, slice);
 	  fx_hex_dump (F->block, FX25_BLOCK_SIZE);
 	}
 	assert (F->block[FX25_BLOCK_SIZE] == FENCE);
@@ -323,10 +324,10 @@ static void process_rs_block (int chan, int subchan, int slice, struct fx_contex
 	  if (fx25_get_debug() >= 2) {
 	    text_color_set(DW_COLOR_INFO);
 	    if (derrors == 0) {
-	      dw_printf ("FX.25: FEC complete with no errors.\n"); 
+	      dw_printf ("FX.25[%d.%d]: FEC complete with no errors.\n", chan, slice);
 	    }
 	    else {
-	      dw_printf ("FX.25: FEC complete, fixed %2d errors in byte positions:",derrors); 
+	      dw_printf ("FX.25[%d.%d]: FEC complete, fixed %2d errors in byte positions:", chan, slice, derrors);
 	      for (int k = 0; k < derrors; k++) {
 	        dw_printf (" %d", derrlocs[k]);
 	      }
@@ -335,7 +336,7 @@ static void process_rs_block (int chan, int subchan, int slice, struct fx_contex
 	  }
 
 	  unsigned char frame_buf[FX25_MAX_DATA+1];	// Out must be shorter than input.
-	  int frame_len = my_unstuff (F->block, F->dlen, frame_buf);
+	  int frame_len = my_unstuff (chan, subchan, slice, F->block, F->dlen, frame_buf);
 
 	  if (frame_len >= 14 + 1 + 2) {		// Minimum length: Two addresses & control & FCS.
 
@@ -345,7 +346,7 @@ static void process_rs_block (int chan, int subchan, int slice, struct fx_contex
 
 	      if (fx25_get_debug() >= 3) {
 	        text_color_set(DW_COLOR_DEBUG);
-	        dw_printf ("FX.25: Extracted AX.25 frame:\n");
+	        dw_printf ("FX.25[%d.%d]: Extracted AX.25 frame:\n", chan, slice);
 	        fx_hex_dump (frame_buf, frame_len);
 	      }
 
@@ -360,22 +361,22 @@ static void process_rs_block (int chan, int subchan, int slice, struct fx_contex
 	    } else {
 	      // Most likely cause is defective sender software.
 	      text_color_set(DW_COLOR_ERROR);
-	      dw_printf ("FX.25: Bad FCS for AX.25 frame.\n");
+	      dw_printf ("FX.25[%d.%d]: Bad FCS for AX.25 frame.\n", chan, slice);
 	      fx_hex_dump (F->block, F->dlen);
 	      fx_hex_dump (frame_buf, frame_len);
 	    }
 	  }
 	  else {
 	    // Most likely cause is defective sender software.
 	    text_color_set(DW_COLOR_ERROR);
-	    dw_printf ("FX.25: AX.25 frame is shorter than minimum length.\n");
+	    dw_printf ("FX.25[%d.%d]: AX.25 frame is shorter than minimum length.\n", chan, slice);
 	    fx_hex_dump (F->block, F->dlen);
 	    fx_hex_dump (frame_buf, frame_len);
 	  }
 	}
 	else if (fx25_get_debug() >= 2) {
 	  text_color_set(DW_COLOR_ERROR);
-	  dw_printf ("FX.25: FEC failed.  Too many errors.\n");
+	  dw_printf ("FX.25[%d.%d]: FEC failed.  Too many errors.\n", chan, slice);
 	}
 
 } // process_rs_block
@@ -387,7 +388,9 @@ static void process_rs_block (int chan, int subchan, int slice, struct fx_contex
  *
  * Purpose:	Remove HDLC it stuffing and surrounding flag delimiters.
  *
- * Inputs:      pin	- "data" part of RS codeblock.
+ * Inputs:      chan, subchan, slice	- For error messages.
+ *
+ *		pin	- "data" part of RS codeblock.
  *			  First byte must be HDLC "flag".
  *			  May be followed by additional flags.
  *			  There must be terminating flag but it might not be byte aligned.
@@ -409,7 +412,7 @@ static void process_rs_block (int chan, int subchan, int slice, struct fx_contex
  *
  ***********************************************************************************/
 
-static int my_unstuff (unsigned char * restrict pin, int ilen, unsigned char * restrict frame_buf)
+static int my_unstuff (int chan, int subchan, int slice, unsigned char * restrict pin, int ilen, unsigned char * restrict frame_buf)
 {
 	unsigned char pat_det = 0;	// Pattern detector.
 	unsigned char oacc = 0;		// Accumulator for a byte out.
@@ -418,7 +421,7 @@ static int my_unstuff (unsigned char * restrict pin, int ilen, unsigned char * r
 	
 	if (*pin != 0x7e) {
 	  text_color_set(DW_COLOR_ERROR);
-	  dw_printf ("FX.25 error: Data section did not start with 0x7e.\n");
+	  dw_printf ("FX.25[%d.%d] error: Data section did not start with 0x7e.\n", chan, slice);
 	  fx_hex_dump (pin, ilen);
 	  return (0);
 	}
@@ -436,7 +439,7 @@ static int my_unstuff (unsigned char * restrict pin, int ilen, unsigned char * r
 
 	    if (pat_det == 0xfe) {
 	      text_color_set(DW_COLOR_ERROR);
-	      dw_printf ("FX.25: Invalid AX.25 frame - Seven '1' bits in a row.\n"); 
+	      dw_printf ("FX.25[%d.%d]: Invalid AX.25 frame - Seven '1' bits in a row.\n", chan, slice);
 	      fx_hex_dump (pin, ilen);
 	      return 0;
 	    }
@@ -451,7 +454,7 @@ static int my_unstuff (unsigned char * restrict pin, int ilen, unsigned char * r
 		}
 	        else {
 	          text_color_set(DW_COLOR_ERROR);
-	          dw_printf ("FX.25: Invalid AX.25 frame - Not a whole number of bytes.\n"); 
+	          dw_printf ("FX.25[%d.%d]: Invalid AX.25 frame - Not a whole number of bytes.\n", chan, slice);
 	          fx_hex_dump (pin, ilen);
 	          return (0);
 	        }
@@ -470,7 +473,7 @@ static int my_unstuff (unsigned char * restrict pin, int ilen, unsigned char * r
 	}	/* end of loop on all bits in block */
 
 	text_color_set(DW_COLOR_ERROR);
-	dw_printf ("FX.25: Invalid AX.25 frame - Terminating flag not found.\n"); 
+	dw_printf ("FX.25[%d.%d]: Invalid AX.25 frame - Terminating flag not found.\n", chan, slice);
 	fx_hex_dump (pin, ilen);
 
 	return (0);	// Should never fall off the end.
diff --git a/src/fx25_send.c b/src/fx25_send.c
@@ -61,7 +61,7 @@ int main ()
 	dw_printf("Run fxrec as second part of test.\n");
 
 	fx25_init (3);
-	for (int i = CTAG_MIN; i <= CTAG_MAX; i++) {
+	for (int i = 100 + CTAG_MIN; i <= 100 + CTAG_MAX; i++) {
 	  fx25_send_frame (0, preload, (int)sizeof(preload)-3, i);
 	}
 	exit(EXIT_SUCCESS);
@@ -115,7 +115,7 @@ int fx25_send_frame (int chan, unsigned char *fbuf, int flen, int fx_mode)
 	if (fx25_get_debug() >= 3) {
 	  text_color_set(DW_COLOR_DEBUG);
 	  dw_printf ("------\n");
-	  dw_printf ("FX.25 send frame: chan = %d, FX.25 mode = %d\n", chan, fx_mode);
+	  dw_printf ("FX.25[%d] send frame: FX.25 mode = %d\n", chan, fx_mode);
 	  fx_hex_dump (fbuf, flen);
 	}
 
@@ -138,7 +138,7 @@ int fx25_send_frame (int chan, unsigned char *fbuf, int flen, int fx_mode)
 	assert (data[FX25_MAX_DATA] == fence);
 	if (dlen < 0) {
 	  text_color_set(DW_COLOR_ERROR);
-	  dw_printf ("FX.25: Frame length of %d + overhead is too large to encode.\n", flen);
+	  dw_printf ("FX.25[%d]: Frame length of %d + overhead is too large to encode.\n", chan, flen);
 	  return (-1);
 	}
 
@@ -150,7 +150,7 @@ int fx25_send_frame (int chan, unsigned char *fbuf, int flen, int fx_mode)
 
 	if (ctag_num < CTAG_MIN || ctag_num > CTAG_MAX) {
 	  text_color_set(DW_COLOR_ERROR);
-	  dw_printf ("FX.25: Could not find suitable format for requested %d and data length %d.\n", fx_mode, dlen);
+	  dw_printf ("FX.25[%d]: Could not find suitable format for requested %d and data length %d.\n", chan, fx_mode, dlen);
 	  return (-1);
 	}
 
@@ -179,9 +179,9 @@ int fx25_send_frame (int chan, unsigned char *fbuf, int flen, int fx_mode)
 
 	if (fx25_get_debug() >= 3) {
 	  text_color_set(DW_COLOR_DEBUG);
-	  dw_printf ("FX.25: transmit %d data bytes, ctag number 0x%02x\n", k_data_radio, ctag_num);
+	  dw_printf ("FX.25[%d]: transmit %d data bytes, ctag number 0x%02x\n", chan, k_data_radio, ctag_num);
 	  fx_hex_dump (data, k_data_radio);
-	  dw_printf ("FX.25: transmit %d check bytes:\n", NROOTS);
+	  dw_printf ("FX.25[%d]: transmit %d check bytes:\n", chan, NROOTS);
 	  fx_hex_dump (check, NROOTS);
 	  dw_printf ("------\n");
 	}
@@ -212,6 +212,11 @@ int fx25_send_frame (int chan, unsigned char *fbuf, int flen, int fx_mode)
 #else
 	// Normal usage.  Send bits to modulator.
 
+// Temp hack for testing.  Corrupt first 8 bytes.
+//	for (int j = 0; j < 16; j++) {
+//	  data[j] = ~ data[j];
+//	}
+
 	for (int k = 0; k < 8; k++) {
 	  unsigned char b = (ctag_value >> (k * 8)) & 0xff;
 	  send_bytes (chan, &b, 1);
