Only update the LSF data once per superframe

SP5WWP/m17-coder/m17-coder-sym.c

@@ -266,6 +266,8 @@ int main(void)
     if(fread(next_data, 16, 1, stdin)<1) finished=1;
 
     while(!finished)
+    {
+        if(lich_cnt == 0)
         {
             lsf = next_lsf;
 
@@ -273,6 +275,7 @@ int main(void)
             uint16_t ccrc=LSF_CRC(&lsf);
             lsf.crc[0]=ccrc>>8;
             lsf.crc[1]=ccrc&0xFF;
+        }
 
         memcpy(data, next_data, sizeof(data));