umapinfo: implement demo extension (#224)

Source/d_main.c

@@ -121,6 +121,8 @@ boolean singletics = false; // debug flag to cancel adaptiveness
 boolean nosfxparm;
 boolean nomusicparm;
 
+boolean umapinfo_loaded = false;
+
 //jff 4/18/98
 extern boolean inhelpscreens;
 
@@ -1639,7 +1641,10 @@ static void D_ProcessUMInWad(int i)
       D_ProcessUMInWad(lumpinfo[i].next);
       if (!strncasecmp(lumpinfo[i].name, "umapinfo", 8) &&
           lumpinfo[i].namespace == ns_global)
-        U_ParseMapInfo((const char *)W_CacheLumpNum(i, PU_CACHE), W_LumpLength(i));
+        {
+          U_ParseMapInfo((const char *)W_CacheLumpNum(i, PU_CACHE), W_LumpLength(i));
+          umapinfo_loaded = true;
+        }
     }
 }
 

Source/d_main.h

@@ -53,6 +53,8 @@ extern boolean pistolstart;
 extern boolean nosfxparm;
 extern boolean nomusicparm;
 
+extern boolean umapinfo_loaded;
+
 // Called by IO functions when input is detected.
 void D_PostEvent(event_t* ev);
 

Source/g_game.c

@@ -1253,12 +1253,78 @@ static void G_DoPlayDemo(void)
     return;
   }
 
+  // ano - jun2019
+  // so the format is
+  // demover byte == 255
+  // "PR+UM" signature (w/ ending null terminator)
+  // extension_version byte. for now this should always be "1"
+  // 2 bytes for num_extensions (little-endian)
+  // num_extensions *
+  //    1 byte string length
+  //    and length chars (up to 65535 obviously)
+  // note that the format has each length by each string
+  // as opposed to a table of lengths
+  // an example extensions string is "UMAPINFO".
+  // then finally the "real" demover byte is present here
+  demover = *demo_p++;
+
+  if (demover == 255)
+  {
+    boolean using_umapinfo = false;
+    int extension_version = -1;
+    int num_extensions;
+
+    // we check for the PR+UM signature as mentioned.
+    // Eternity Engine also uses 255 demover, with other signatures.
+    if (strncmp((const char *)demo_p, "PR+UM", 5) != 0)
+    {
+      I_Error("G_DoPlayDemo: Extended demo format 255 found, but \"PR+UM\" string not found.");
+    }
+
+    demo_p += 6;
+    extension_version = *demo_p++;
+
+    if (extension_version != 1)
+    {
+      I_Error("G_DoPlayDemo: Extended demo format version %d unrecognized.", extension_version);
+    }
+
+    num_extensions  =                 *demo_p++;
+    num_extensions |= ((unsigned int)(*demo_p++)) <<  8;
+
+    for (i = 0; i < num_extensions; i++)
+    {
+      int r_len = *demo_p++;
+
+      // ano - jun2019 - when more potential extension strings get added,
+      // this section can become more complex
+      if (r_len == 8 && strncmp((const char *)demo_p, "UMAPINFO", 8) == 0)
+      {
+        using_umapinfo = true;
+      }
+      else
+      {
+        I_Error("G_DoPlayDemo: Extended demo format extension unrecognized.");
+      }
+
+      demo_p += r_len;
+    }
+
+    // skip map name
+    if (using_umapinfo)
+    {
+      demo_p += 8;
+    }
+    // ano - jun2019 - this is to support other demovers effectively?
+    // while still having the extended features
+    demover = *demo_p++;
+  }
+
   // killough 2/22/98, 2/28/98: autodetect old demos and act accordingly.
   // Old demos turn on demo_compatibility => compatibility; new demos load
   // compatibility flag, and other flags as well, as a part of the demo.
 
-  demo_version =      // killough 7/19/98: use the version id stored in demo
-  demover = *demo_p++;
+  demo_version = demover;     // killough 7/19/98: use the version id stored in demo
 
   // [FG] PrBoom's own demo format starts with demo version 210
   if (demover >= 210 && demover != MBF21VERSION)
@@ -3025,6 +3091,68 @@ void G_BeginRecording(void)
 
   demo_p = demobuffer;
 
+  if (umapinfo_loaded)
+  {
+    int num_extensions = 1;
+    char mapname[9] = {0};
+
+    // demover
+    *demo_p++ = 0xFF;
+    // signature
+    *demo_p++ = 'P';
+    *demo_p++ = 'R';
+    *demo_p++ = '+';
+    *demo_p++ = 'U';
+    *demo_p++ = 'M';
+    *demo_p++ = '\0';
+    // extension version
+    *demo_p++ = 1;
+    //
+    *demo_p++ =  num_extensions & 0xff;
+    *demo_p++ = (num_extensions >> 8) & 0xff;
+
+    // ano - note that the format has each length by each string
+    // as opposed to a table of lengths
+    *demo_p++ = 0x08;
+    *demo_p++ = 'U';
+    *demo_p++ = 'M';
+    *demo_p++ = 'A';
+    *demo_p++ = 'P';
+    *demo_p++ = 'I';
+    *demo_p++ = 'N';
+    *demo_p++ = 'F';
+    *demo_p++ = 'O';
+    // ano - to properly extend this to support other extension strings
+    // we wouldn't just plop this here, but right now we only support the 1
+    // in the future, we should assume that chunks in the header should
+    // follow the order of their appearance in the extensions table.
+
+    // [XA] get the map name from gamemapinfo if the
+    // starting map has a UMAPINFO definition. if not,
+    // fall back to the usual MAPxx/ExMy default.
+    if (gamemapinfo)
+    {
+      strncpy(mapname, gamemapinfo->mapname, 8);
+    }
+    else if(gamemode == commercial)
+    {
+      snprintf(mapname, 9, "MAP%02d", gamemap);
+    }
+    else
+    {
+      snprintf(mapname, 9, "E%dM%d", gameepisode, gamemap);
+    }
+
+    for (i = 0; i < 8; i++)
+    {
+      // FIXME - the toupper is a hacky workaround for the case insensitivity
+      // in the current UMAPINFO reader. lump names should probably not be
+      // lowercase ever (?)
+      *demo_p++ = toupper(mapname[i]);
+    }
+  }
+  // ano - done with the extension format!
+
   if (complevel == MBFVERSION || complevel == MBF21VERSION)
   {
     if (complevel == MBF21VERSION)
@@ -3051,8 +3179,6 @@ void G_BeginRecording(void)
   *demo_p++ = compatibility;       // killough 2/22/98
   }
 
-  demo_version = complevel;
-
   *demo_p++ = gameskill;
   *demo_p++ = gameepisode;
   *demo_p++ = gamemap;