coding: fix wrong n_bits_total reported for PDTCH CS2 and CS3

In gsm0503_pdtch_decode(), we decode CS2 and CS3 as if no puncturing
was employed, reordering the coded bits and setting punctured ones
to 0 manually.  Because of that, osmo_conv_decode_ber_punctured()
reports n_bits_total higher than we actually receive over the air.

Change-Id: I6b20cc450f25c48175a61da02644d66c08e22ece
Related: OS#6342, OS#6200

2 files changed, 16 insertions, 7 deletions

diff --git a/src/coding/gsm0503_coding.c b/src/coding/gsm0503_coding.c
index 69a7ad40..022f4656 100644
--- a/src/coding/gsm0503_coding.c
+++ b/src/coding/gsm0503_coding.c
@@ -1059,6 +1059,7 @@ int gsm0503_pdtch_decode(uint8_t *l2_data, const sbit_t *bursts, uint8_t *usf_p,
 
 		return 23;
 	case 2:
+		/* reorder, set punctured bits to 0 (unknown state) */
 		for (i = 587, j = 455; i >= 0; i--) {
 			if (!gsm0503_puncture_cs2[i])
 				cB[i] = cB[j--];
@@ -1066,10 +1067,13 @@ int gsm0503_pdtch_decode(uint8_t *l2_data, const sbit_t *bursts, uint8_t *usf_p,
 				cB[i] = 0;
 		}
 
+		/* decode as if puncturing was not employed (note '_np') */
 		osmo_conv_decode_ber_punctured(&gsm0503_cs2_np, cB, conv,
-					       n_errors, n_bits_total,
+					       n_errors, NULL,
 					       gsm0503_puncture_cs2);
-
+		/* indicate the actual amount of coded bits (excluding punctured ones) */
+		if (n_bits_total != NULL)
+			*n_bits_total = 456;
 
 		/* 5.1.2.2 a) the three USF bits d(0),d(1),d(2) are precoded into six bits */
 		for (i = 0; i < 8; i++) {
@@ -1097,6 +1101,7 @@ int gsm0503_pdtch_decode(uint8_t *l2_data, const sbit_t *bursts, uint8_t *usf_p,
 
 		return 34;
 	case 3:
+		/* reorder, set punctured bits to 0 (unknown state) */
 		for (i = 675, j = 455; i >= 0; i--) {
 			if (!gsm0503_puncture_cs3[i])
 				cB[i] = cB[j--];
@@ -1104,9 +1109,13 @@ int gsm0503_pdtch_decode(uint8_t *l2_data, const sbit_t *bursts, uint8_t *usf_p,
 				cB[i] = 0;
 		}
 
+		/* decode as if puncturing was not employed (note '_np') */
 		osmo_conv_decode_ber_punctured(&gsm0503_cs3_np, cB, conv,
-					       n_errors, n_bits_total,
+					       n_errors, NULL,
 					       gsm0503_puncture_cs3);
+		/* indicate the actual amount of coded bits (excluding punctured ones) */
+		if (n_bits_total != NULL)
+			*n_bits_total = 456;
 
 		/* 5.1.3.2 a) the three USF bits d(0),d(1),d(2) are precoded into six bits */
 		for (i = 0; i < 8; i++) {
diff --git a/tests/coding/coding_test.ok b/tests/coding/coding_test.ok
index ad8a98d5..6767aeaf 100644
--- a/tests/coding/coding_test.ok
+++ b/tests/coding/coding_test.ok
@@ -270,7 +270,7 @@ S-Bits:
 7f 7f 7f 81 7f 81 81 81 81 81 81 81 81 81 7f 7f 7f 7f 7f 81 81 81 81 7f 81 81 7f 7f 7f 7f 7f 81 81 7f 7f 7f 7f 7f 7f 81 7f 7f 81 81 7f 7f 7f 81 81 7f 81 7f 7f 7f 81 81 7f  81  7f  7f 81 81 7f 81 7f 7f 81 81 7f 81 7f 7f 81 7f 7f 81 7f 81 81 7f 7f 7f 7f 7f 81 7f 81 7f 7f 7f 7f 81 81 7f 7f 81 81 7f 7f 7f 7f 81 81 7f 81 81 7f 81 81 7f 7f 81 81 7f 81 81 
 7f 81 81 81 81 7f 81 7f 7f 7f 81 81 7f 7f 7f 7f 81 81 81 7f 7f 7f 81 7f 81 7f 7f 7f 81 81 81 7f 81 81 81 7f 7f 7f 81 81 81 7f 81 81 7f 81 81 7f 7f 81 81 7f 81 81 81 81 81  7f  7f  7f 7f 7f 81 81 81 81 7f 7f 7f 81 81 81 7f 7f 7f 81 81 7f 81 7f 7f 7f 81 81 7f 81 81 81 7f 7f 81 7f 81 81 81 7f 81 81 81 81 81 7f 81 7f 81 81 81 81 81 7f 81 81 7f 7f 81 81 
 Decoded: a3 af 5f c6 36 43 44 ab d9 6d 7d 62 24 c9 d2 92 fa 27 5d 71 7a 59 a8 42 a3 af 5f c6 36 43 44 ab a3 2f 
-pdtch_decode: n_errors=0 n_bits_total=588 ber=0.00
+pdtch_decode: n_errors=0 n_bits_total=456 ber=0.00
 
 Encoding: a3 af 5f c6 36 43 44 ab d9 6d 7d 62 24 c9 d2 92 fa 27 5d 71 7a 59 a8 42 a3 af 5f c6 36 43 44 ab a3 af 5f c6 36 43 44 03 
 U-Bits:
@@ -284,7 +284,7 @@ S-Bits:
 81 81 7f 7f 7f 81 81 7f 7f 7f 7f 7f 7f 7f 81 7f 7f 7f 7f 81 7f 81 7f 81 7f 81 81 81 81 81 81 7f 81 7f 81 81 7f 7f 7f 81 81 81 7f 81 7f 81 81 81 81 81 7f 7f 81 81 81 81 7f  7f  7f  81 7f 7f 7f 7f 81 81 7f 81 81 7f 7f 7f 81 81 7f 7f 81 81 7f 81 81 7f 7f 81 81 7f 81 81 7f 7f 7f 7f 81 7f 81 7f 7f 7f 7f 7f 81 7f 7f 7f 7f 7f 81 7f 81 81 7f 7f 81 81 81 7f 
 7f 81 81 81 7f 7f 7f 7f 81 7f 81 7f 7f 7f 7f 81 7f 7f 81 7f 7f 81 7f 81 7f 7f 81 7f 7f 7f 81 7f 7f 81 81 7f 81 7f 7f 81 81 81 7f 81 7f 7f 7f 7f 81 7f 81 81 81 7f 7f 7f 7f  7f  81  81 81 81 81 7f 7f 81 81 7f 7f 7f 7f 7f 81 81 7f 7f 81 7f 7f 81 81 7f 81 81 81 7f 81 7f 7f 81 81 81 81 7f 81 7f 7f 81 7f 81 7f 7f 81 81 81 81 7f 81 7f 7f 81 81 7f 7f 81 81 
 Decoded: a3 af 5f c6 36 43 44 ab d9 6d 7d 62 24 c9 d2 92 fa 27 5d 71 7a 59 a8 42 a3 af 5f c6 36 43 44 ab a3 af 5f c6 36 43 44 03 
-pdtch_decode: n_errors=0 n_bits_total=676 ber=0.00
+pdtch_decode: n_errors=0 n_bits_total=456 ber=0.00
 
 Encoding: a3 af 5f c6 36 43 44 ab d9 6d 7d 62 24 c9 d2 92 fa 27 5d 71 7a 59 a8 42 a3 af 5f c6 36 43 44 ab a3 af 5f c6 36 43 44 ab d9 6d 7d 62 24 c9 d2 92 fa 27 5d 71 7a 28 
 U-Bits:
@@ -326,7 +326,7 @@ S-Bits:
 7f 7f 81 7f 81 81 7f 7f 7f 81 7f 7f 7f 81 81 7f 81 7f 81 7f 7f 7f 7f 7f 81 7f 81 81 81 7f 81 7f 7f 7f 81 7f 7f 81 7f 7f 81 7f 7f 7f 81 7f 81 81 81 81 7f 81 7f 81 7f 7f 81  81  7f  7f 7f 7f 81 81 7f 7f 7f 7f 7f 81 81 7f 7f 7f 81 7f 7f 7f 81 81 7f 7f 7f 81 7f 7f 81 7f 81 7f 7f 7f 81 7f 7f 7f 7f 81 7f 7f 7f 7f 7f 7f 81 7f 7f 81 7f 81 7f 7f 81 7f 81 81 
 81 7f 81 7f 7f 81 7f 7f 81 81 7f 7f 81 7f 81 7f 7f 81 81 81 7f 81 7f 81 81 7f 81 7f 81 7f 81 7f 81 7f 7f 7f 7f 7f 7f 81 81 7f 81 7f 7f 7f 81 7f 7f 7f 7f 7f 81 7f 81 7f 81  7f  7f  7f 81 7f 81 7f 7f 81 7f 81 81 81 7f 7f 81 7f 7f 7f 81 7f 7f 7f 7f 81 81 7f 81 81 81 7f 7f 7f 81 7f 7f 7f 7f 81 81 81 7f 7f 7f 7f 81 7f 7f 81 7f 81 7f 7f 81 81 7f 7f 81 7f 
 Decoded: 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 00 00 00 00 00 00 00 00 00 00 00 
-pdtch_decode: n_errors=0 n_bits_total=588 ber=0.00
+pdtch_decode: n_errors=0 n_bits_total=456 ber=0.00
 
 Encoding: 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
 U-Bits:
@@ -340,7 +340,7 @@ S-Bits:
 81 7f 81 7f 81 81 7f 7f 7f 81 7f 81 7f 7f 81 7f 7f 7f 81 7f 7f 81 7f 7f 7f 7f 81 7f 7f 7f 7f 7f 81 81 7f 7f 7f 7f 7f 81 81 81 7f 7f 7f 7f 81 81 7f 81 7f 7f 7f 7f 7f 81 7f  7f  7f  7f 81 7f 81 81 7f 7f 7f 81 7f 81 81 7f 81 7f 7f 7f 81 7f 7f 7f 7f 81 7f 7f 7f 81 7f 7f 81 7f 7f 7f 7f 81 7f 81 7f 81 7f 7f 81 7f 81 7f 7f 7f 7f 7f 7f 7f 7f 81 81 81 7f 7f 
 7f 7f 81 7f 7f 7f 7f 81 7f 81 7f 7f 81 7f 7f 7f 7f 81 7f 81 7f 7f 7f 81 7f 7f 81 7f 7f 7f 81 81 7f 81 7f 7f 7f 81 7f 81 7f 7f 7f 7f 81 81 7f 81 7f 81 7f 7f 81 7f 81 7f 81  7f  81  7f 7f 7f 7f 7f 7f 81 7f 81 81 81 81 7f 7f 7f 7f 7f 7f 81 7f 7f 7f 81 81 7f 81 7f 81 7f 7f 7f 81 7f 7f 81 7f 81 81 7f 81 7f 81 7f 7f 7f 7f 81 7f 7f 7f 81 81 81 81 7f 7f 7f 
 Decoded: 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
-pdtch_decode: n_errors=0 n_bits_total=676 ber=0.00
+pdtch_decode: n_errors=0 n_bits_total=456 ber=0.00
 
 Encoding: 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f 10 11 12 13 14 15 16 17 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
 U-Bits: