From db6af0f2f4f826489a542d3f22153da788ffef09 Mon Sep 17 00:00:00 2001
From: Pawel Jalocha <Pawel.Jalocha@gmail.com>
Date: Sun, 7 Aug 2022 05:01:03 +0100
Subject: [PATCH] Keep APRS messages within the IGC

---
 utils/aprs2igc.cc | 38 ++++++++++++++++++++++----------------
 utils/ognconv.cpp |  2 +-
 2 files changed, 23 insertions(+), 17 deletions(-)

diff --git a/utils/aprs2igc.cc b/utils/aprs2igc.cc
index e6c1886..7ccbf26 100644
--- a/utils/aprs2igc.cc
+++ b/utils/aprs2igc.cc
@@ -12,9 +12,12 @@
 
 static bool Earlier(const char *Line1, const char *Line2) { return strcmp(Line1, Line2)<0; }
 
-static int Verbose    =  1;
+static int Verbose    =  0;
 static int GeoidSepar = 40;
 
+const int MaxLineLen = 256;
+const int MaxIGClen  =  64;
+
 static FILE *OutFile = 0;
 
 int main(int argc, char *argv[])
@@ -22,8 +25,8 @@ int main(int argc, char *argv[])
   { printf("Usage: %s <own-aircraft-APRS-call> <input-file.aprs>\n", argv[0]);
     return 0; }
 
-  const char *OwnAcft = argv[1]; int OwnAcftLen = strlen(OwnAcft);
-  char OutFileName[32]; strcpy(OutFileName, OwnAcft); strcat(OutFileName, ".IGC");
+  const char *OwnAcft = argv[1]; int OwnAcftLen = strlen(OwnAcft);       // target aircraft APRS name
+  char OutFileName[32]; strcpy(OutFileName, OwnAcft); strcat(OutFileName, ".IGC"); // create the IGC file name
 
   const char *InpFileName = argv[2];
   FILE *InpFile;
@@ -33,32 +36,35 @@ int main(int argc, char *argv[])
     if(InpFile==0) { printf("Cannot open %s for read\n", InpFileName); return 0; }
   }
 
-  std::vector<char *> OutLine;
-  char InpLine[256];
-  // char OutLine[256];
+  std::vector<char *> OutLine;                                           // list of APRS lines for the selected aircraft
+  char InpLine[MaxLineLen];
+  // char OutLine[MaxLineLen];
   int InpLines=0;
   // int OutLines=0;
-  char *Out=0;
+  char *Out=0;                                                           // (new) IGC line allocated
   for( ; ; )
-  { if(fgets(InpLine, 256, InpFile)==0) break;
+  { if(fgets(InpLine, MaxLineLen, InpFile)==0) break;                    // read line from the input
     char *EOL = strchr(InpLine, '\n'); if(EOL==0) break;
     *EOL = 0;
     InpLines++;
-    if(memcmp(InpLine, OwnAcft, OwnAcftLen)) continue;
-    if(Out==0) Out = (char *)malloc(60);
-    int OutLen=APRS2IGC(Out, InpLine, GeoidSepar);
-    if(OutLen>0)
-    { if(Verbose) printf("%s => %s [%d]\n", InpLine, Out, OutLen);
-      OutLine.push_back(Out); Out=0; }
+    if(memcmp(InpLine, OwnAcft, OwnAcftLen)) continue;                   // must start with the selected APRS name
+    if(Out==0) Out = (char *)malloc(MaxIGClen+MaxLineLen);               // allocated (new) IGC line
+    int OutLen=APRS2IGC(Out, InpLine, GeoidSepar);                       // convert APRS to IGC B-record
+    if(OutLen>0)                                                         // if correct conversion
+    { // if(Verbose) printf("%s => %s [%d]\n", InpLine, Out, OutLen);
+      OutLen += Format_String(Out+OutLen, "LGNE ");
+      OutLen += Format_String(Out+OutLen, InpLine);
+      Out[OutLen++] = '\n'; Out[OutLen] = 0;
+      OutLine.push_back(Out); Out=0; }                                   // add the new IGC line to the list
   }
   if(Out) { free(Out); Out=0; }
   if(InpFile!=stdin) fclose(InpFile);
   printf("%d lines from %s\n", InpLines, InpFileName);
 
-  std::sort(OutLine.begin(), OutLine.end(), Earlier);
+  std::sort(OutLine.begin(), OutLine.end(), Earlier);                    // sort the IGC B-record lines
   OutFile=fopen(OutFileName, "wt");
   if(OutFile==0) { printf("Cannot open %s for write\n", OutFileName); return 0; }
-  for(size_t Idx=0; Idx<OutLine.size(); Idx++)
+  for(size_t Idx=0; Idx<OutLine.size(); Idx++)                           // look over (now sorted) IGC B-records
   { fprintf(OutFile, "%s", OutLine[Idx]); }
   fclose(OutFile);
   printf("%lu lines to %s\n", OutLine.size(), OutFileName);
diff --git a/utils/ognconv.cpp b/utils/ognconv.cpp
index 5393e8a..6de1425 100644
--- a/utils/ognconv.cpp
+++ b/utils/ognconv.cpp
@@ -277,7 +277,7 @@ int APRS2IGC(char *Out, const char *Inp, int GeoidSepar)             // convert
   Msg++;                                                             // where message starts
   if(Msg[0]!='/' || Msg[7]!='h') return 0;
   const char *Pos = Msg+8; if(Pos[4]!='.' || Pos[14]!='.') return 0; // where position starts
-  const char *ExtPos = strstr(Pos+18, " !W"); if(ExtPos[5]=='!') ExtPos+=3; else ExtPos=0;
+  const char *ExtPos = strstr(Pos+18, " !W"); if(ExtPos && ExtPos[5]=='!') ExtPos+=3; else ExtPos=0;
   Out[Len++]='B';                                                    // B-record
   memcpy(Out+Len, Msg+1, 6); Len+=6;                                 // copy UTC time
   memcpy(Out+Len, Pos, 4); Len+=4;                                   // copy DDMM