Added 'virtual resource' mechanism for temporary memory loaded lump lists. If you can come up with a better name then I'm all ears.

src/w_wad.c

@@ -1888,3 +1888,98 @@ int W_VerifyNMUSlumps(const char *filename)
 	};
 	return W_VerifyFile(filename, NMUSlist, false);
 }
+
+/** \brief Generates a virtual resource used for level data loading.
+ *
+ * \param lumpnum_t reference
+ * \return Virtual resource
+ *
+ */
+virtres_t* vres_GetMap (lumpnum_t lumpnum)
+{
+	UINT32 i;
+	virtres_t*	vres	= NULL;
+	virtlump_t*	vlumps	= NULL;
+	size_t	numlumps	= 0;
+
+	if (W_IsLumpWad(lumpnum))
+	{
+		// Remember that we're assuming that the WAD will have a specific set of lumps in a specific order.
+		UINT8 *wadData = W_CacheLumpNum(lumpnum, PU_LEVEL);
+		filelump_t *fileinfo = (filelump_t *)(wadData + ((wadinfo_t *)wadData)->infotableofs);
+		numlumps = ((wadinfo_t *)wadData)->numlumps;
+		vlumps = Z_Malloc(sizeof(virtlump_t)*numlumps, PU_LEVEL, NULL);
+
+		// Build the lumps.
+		for (i = 0; i < numlumps; i++)
+		{
+			vlumps[i].size = (size_t)(((filelump_t *)(fileinfo + i))->size);
+			// Play it safe with the name in this case.
+			memcpy(vlumps[i].name, (fileinfo + i)->name, 8);
+			vlumps[i].name[8] = '\0';
+			vlumps[i].data = Z_Malloc(vlumps[i].size, PU_LEVEL, NULL); // This is memory inefficient, sorry about that.
+			memcpy(vlumps[i].data, wadData + (fileinfo + i)->filepos, vlumps[i].size);
+		}
+
+		Z_Free(wadData);
+	}
+	else
+	{
+		// Count number of lumps until the end of resource OR up until next "MAPXX" lump.
+		lumpnum_t lumppos = lumpnum + 1;
+		for (i = LUMPNUM(lumppos); i < wadfiles[WADFILENUM(lumpnum)]->numlumps; i++, lumppos++, numlumps++)
+			if (memcmp(W_CheckNameForNum(lumppos), "MAP", 3) == 0)
+				break;
+		numlumps++;
+
+		vlumps = Z_Malloc(sizeof(virtlump_t)*numlumps, PU_LEVEL, NULL);
+		for (i = 0; i < numlumps; i++, lumpnum++)
+		{
+			vlumps[i].size = W_LumpLength(lumpnum);
+			memcpy(vlumps[i].name, W_CheckNameForNum(lumpnum), 8);
+			vlumps[i].name[8] = '\0';
+			vlumps[i].data = W_CacheLumpNum(lumpnum, PU_LEVEL);
+		}
+	}
+	vres = Z_Malloc(sizeof(virtres_t), PU_LEVEL, NULL);
+	vres->vlumps	= vlumps;
+	vres->numlumps	= numlumps;
+	return vres;
+}
+
+/** \brief Frees zone memory for a given virtual resource.
+ *
+ * \param Virtual resource
+ */
+void vres_Free (virtres_t* vres)
+{
+	while (vres->numlumps--)
+		Z_Free(vres->vlumps[vres->numlumps].data);
+	Z_Free(vres->vlumps);
+	Z_Free(vres);
+}
+
+/** (Debug) Prints lumps from a virtual resource into console.
+ */
+static void vres_Diag (const virtres_t* vres)
+{
+	UINT32 i;
+	for (i = 0; i < vres->numlumps; i++)
+		CONS_Printf("%s\n", vres->vlumps[i].name);
+}
+
+/** \brief Finds a lump in a given virtual resource.
+ *
+ * \param Virtual resource
+ * \param Lump name to look for
+ * \return Virtual lump if found, NULL otherwise
+ *
+ */
+virtlump_t* vres_Find(const virtres_t* vres, const char* name)
+{
+	UINT32 i;
+	for (i = 0; i < vres->numlumps; i++)
+		if (fastcmp(name, vres->vlumps[i].name))
+			return &vres->vlumps[i];
+	return NULL;
+}

src/w_wad.h

@@ -72,6 +72,25 @@ typedef struct
 	compmethod compression; // lump compression method
 } lumpinfo_t;
 
+// =========================================================================
+//                         'VIRTUAL' RESOURCES
+// =========================================================================
+
+typedef struct {
+	char name[9];
+	UINT8* data;
+	size_t size;
+} virtlump_t;
+
+typedef struct {
+	size_t numlumps;
+	virtlump_t* vlumps;
+} virtres_t;
+
+virtres_t* vres_GetMap (lumpnum_t);
+void vres_Free (virtres_t*);
+virtlump_t* vres_Find (const virtres_t*, const char*);
+
 // =========================================================================
 //                         DYNAMIC WAD LOADING
 // =========================================================================