Move Hagelbarger error correction code from NMT to common code

It will be used by Radiocom 2000 also.
Some minor fixes and improvements apply.

src/nmt/Makefile.am

@@ -8,7 +8,6 @@ nmt_SOURCES = \
 	countries.c \
 	transaction.c \
 	dsp.c \
-	hagelbarger.c \
 	frame.c \
 	dms.c \
 	sms.c \

src/nmt/frame.c

@@ -25,9 +25,9 @@
 #include "../common/sample.h"
 #include "../common/debug.h"
 #include "../common/timer.h"
+#include "../common/hagelbarger.h"
 #include "nmt.h"
 #include "frame.h"
-#include "hagelbarger.h"
 
 uint64_t nmt_encode_channel(int nmt_system, int channel, int power)
 {
@@ -1146,7 +1146,7 @@ const char *encode_frame(int nmt_system, frame_t *frame, int debug)
 	message[8] = 0x00;
 	for (i = 0; i < 8; i++)
 		message[i] = (digits[i * 2] << 4) | digits[i * 2 + 1];
-	hagelbarger_encode(message, code, 72);
+	hagelbarger_encode(message, code, 70);
 	memcpy(bits, "10101010101010111100010010", 26);
 	for (i = 0; i < 140; i++)
 		bits[i + 26] = ((code[i / 8] >> (7 - (i & 7))) & 1) + '0';

src/nmt/hagelbarger.c

@@ -1,87 +0,0 @@
-/* Hagelbarger (6,19) code
- *
- * A burst up to 6 encoded bits may be corrupt, to correct them.
- * After corrupt bits, a minimum of 19 bits must be correct to correct
- * another burst of corrupted bits.
- *
- * There is no parity check, so it is required to check all information
- * elements of each message. Messages that contain signals or digits are
- * protected by repeating the digits in the information element.
- *
- * (C) 2017 by Andreas Eversberg <jolly@eversberg.eu>
- * All Rights Reserved
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include "stdint.h"
-
-/* To encode NMT message: (MSB first)
- * Use input with 9 bytes, the last byte must be 0x00.
- * Use output with 18 bytes, ignore the last four (lower) bits of last byte.
- * Use length of 72.
- */
-void hagelbarger_encode(const uint8_t *input, uint8_t *output, int length)
-{
-	uint8_t reg = 0x00, data, check;
-	int i;
-
-	for (i = 0; i < length; i++) {
-		/* get data from input (MSB first) */
-		data = (input[i / 8] >> (7 - (i & 7))) & 1;
-		/* push data into shift register (LSB first) */
-		reg = (reg << 1) | data;
-		/* get data bit from register */
-		data = (reg >> 6) & 1;
-		/* calc check bit from register */
-		check = (reg + (reg >> 3) + 1) & 1;
-		/* put check bit and data bit to output (MSB first) */
-		output[i / 4] = (output[i / 4] << 2) | (check << 1) | data;
-	}
-}
-
-/* To decode NMT message: (MSB first)
- * Use input with 19 bytes, the unused last 12 (lower) bits must be zero.
- * Use output with 8 bytes.
- * Use length of 64.
- */
-void hagelbarger_decode(const uint8_t *input, uint8_t *output, int length)
-{
-	uint16_t reg_data = 0x00, reg_check = 0x00, data, check, r_parity, s_parity;
-	int i;
-
-	length += 10;
-
-	for (i = 0; i < length; i++) {
-		/* get check bit from input (MSB first) */
-		check = (input[i / 4] >> (7 - (i & 3) * 2)) & 1;
-		/* get data bit from input (MSB first) */
-		data = (input[i / 4] >> (6 - (i & 3) * 2)) & 1;
-		/* push check bit into shift register (LSB first) */
-		reg_check = (reg_check << 1) | check;
-		/* push data bit into shift register (LSB first) */
-		reg_data = (reg_data << 1) | data;
-		/* calculate parity */
-		r_parity = (reg_data + (reg_data >> 3) + (reg_check >> 6) + 1) & 1;
-		s_parity = ((reg_data >> 3) + (reg_data >> 6) + (reg_check >> 9) + 1) & 1;
-		/* flip message bit, if both parity checks fail */
-		/* use 4th bit that will be shifted to 5th bit next loop */
-		if (r_parity && s_parity)
-			reg_data ^= 0x0008;
-		/* put message bit to output (MSB first) */
-		if (i >= 10)
-			output[(i - 10) / 8] = (output[(i - 10) / 8] << 1) | ((reg_data >> 4) & 1);
-	}
-}
-

src/nmt/hagelbarger.h

@@ -1,4 +0,0 @@
-
-void hagelbarger_encode(const uint8_t *input, uint8_t *output, int length);
-void hagelbarger_decode(const uint8_t *input, uint8_t *output, int length);
-