From 3a5b28675c4755bad0300c97374a26740dbd0a64 Mon Sep 17 00:00:00 2001
From: csrichter <csrichter@hotmail.de>
Date: Fri, 2 Jun 2017 15:16:54 +0200
Subject: [PATCH] RDS error correction fixed? (XORd offsetword to block before
 correcting)

---
 lib/rds_decoder_redsea_impl.cc | 31 ++++++++++++++++++++++---------
 lib/rds_decoder_redsea_impl.h  |  1 +
 2 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/lib/rds_decoder_redsea_impl.cc b/lib/rds_decoder_redsea_impl.cc
index 8e4aaba..080fbca 100644
--- a/lib/rds_decoder_redsea_impl.cc
+++ b/lib/rds_decoder_redsea_impl.cc
@@ -179,15 +179,15 @@ static const char * const offset_name[]={"A","B","C","D","c"};*/
 }
 
 uint32_t rds_decoder_redsea_impl::correctBurstErrors(uint32_t block, char offset) {
-  uint32_t syndrome = calc_syndrome(block,26);
-  //uint32_t syndrome = calcSyndrome_vec(block);
+  //uint32_t syndrome = calc_syndrome(block,26);
+  uint32_t syndrome = calc_syndrome(block ^ offset_char_to_word(offset),26);
   uint32_t corrected_block = block;
   //dout << "trying to correct sy:"<<syndrome<<"\t\toffset:"<<offset;//<<std::endl;
   //dout << "\tcount:"<<kErrorLookup.count({(uint16_t)syndrome, (char)offset})<<std::endl;
   if (kErrorLookup.count({syndrome, offset}) > 0) {
     uint32_t err = kErrorLookup.at({syndrome, offset});
     //dout << "correcting"<<std::endl;
-    err=0;//correction disabled
+    //err=0;//disables error correction
     corrected_block ^= err;
     
   }
@@ -221,6 +221,19 @@ void rds_decoder_redsea_impl::decode_group(uint16_t *group) {
         pmt::pmt_t pdu(pmt::cons(meta, data));  // make PDU: (metadata, data) pair
         message_port_pub(pmt::mp("out"), pdu);
 }
+unsigned int rds_decoder_redsea_impl::offset_char_to_word(char offset_char){
+//  {'A','B','C','D','c'};
+//  {252,408,360,436,848};
+  switch(offset_char){
+    case 'A':return offset_word[0];
+    case 'B':return offset_word[1];
+    case 'C':return offset_word[2];
+    case 'D':return offset_word[3];
+    case 'c':return offset_word[4];
+  }
+  std::cout << "error converting offset char to word"<<std::endl;
+  return 0;//
+}
 //work function
 int rds_decoder_redsea_impl::work (int noutput_items,
                 gr_vector_const_void_star &input_items,
@@ -350,11 +363,11 @@ int rds_decoder_redsea_impl::work (int noutput_items,
                                                         dataword=(corrected_block>>10) & 0xffff;
                                                         checkword=corrected_block & 0x3ff;
                                                         
-                                                        //dout << "corrected error"<<std::endl;
-//                                                         dout << "old: rx:"<<block_received_crc<<"\tcalc:"<<block_calculated_crc<<std::endl;
-//                                                         block_received_crc=checkword^offset_word[block_number];
-//                                                         block_calculated_crc=calc_syndrome(dataword,16);
-//                                                         dout << "new: rx:"<<block_received_crc<<"\tcalc:"<<block_calculated_crc<<std::endl;
+                                                        dout << "corrected error:"<<std::endl;
+                                                        dout << "old: rx:"<<block_received_crc<<"\tcalc:"<<block_calculated_crc<<std::endl;
+                                                        block_received_crc=checkword^offset_word[block_number];
+                                                        block_calculated_crc=calc_syndrome(dataword,16);
+                                                        dout << "new: rx:"<<block_received_crc<<"\tcalc:"<<block_calculated_crc<<std::endl;
                                                         
                                                         offset_char=expected_offset_char[block_number];
                                                   }
@@ -374,7 +387,7 @@ int rds_decoder_redsea_impl::work (int noutput_items,
                                         }
                                         if (block_number==1 && good_block) {//2nd block - > read group type variant
                                                 variant=(dataword>>11)& 0x1;
-                                                uint8_t group=(dataword>>12)& 0xf;
+//                                                 uint8_t group=(dataword>>12)& 0xf;
 //                                                 dout << "group:"<<std::setw(2)<< unsigned(group);
 //                                                 //dout << "\tvariant:" << unsigned(variant);
 //                                                 if (variant==0)
diff --git a/lib/rds_decoder_redsea_impl.h b/lib/rds_decoder_redsea_impl.h
index 2c5f09f..1053877 100644
--- a/lib/rds_decoder_redsea_impl.h
+++ b/lib/rds_decoder_redsea_impl.h
@@ -76,6 +76,7 @@ private:
         eOffset offsetForSyndrome(uint16_t syndrome);
         eOffset nextOffsetFor(eOffset o);
         uint32_t correctBurstErrors(uint32_t block, char offset);
+        unsigned int offset_char_to_word(char offset_char);
         
 
     };