documented pack classes, restored old substream creation for FilePack

svn-id: r48324

2 files changed, 6 insertions, 12 deletions

diff --git a/engines/teenagent/pack.cpp b/engines/teenagent/pack.cpp
index c342ea7134..fa57256b3b 100644
--- a/engines/teenagent/pack.cpp
+++ b/engines/teenagent/pack.cpp
@@ -49,12 +49,7 @@ bool FilePack::open(const Common::String &filename) {
 	offsets = new uint32[_fileCount + 1];
 	for (uint32 i = 0; i <= _fileCount; ++i) {
 		offsets[i] = file.readUint32LE();
-		//debug(0, "%d: %06x", i, offsets[i]);
 	}
-	/*	for (uint32 i = 0; i < count; ++i) {
-			debug(0, "%d: len = %d", i, offsets[i + 1] - offsets[i]);
-		}
-	*/
 	return true;
 }
 
@@ -79,13 +74,7 @@ Common::SeekableReadStream *FilePack::getStream(uint32 id) const {
 	if (id < 1 || id > _fileCount)
 		return NULL;
 	//debug(0, "stream: %04x-%04x", offsets[id - 1], offsets[id]);
-	file.seek(offsets[id - 1]);
-	uint32 size = offsets[id] - offsets[id - 1];
-	byte *ptr = (byte *)malloc(size);
-	if (ptr == NULL)
-		return NULL;
-	uint32 r = file.read(ptr, size);
-	return new Common::MemoryReadStream(ptr, r, DisposeAfterUse::YES);
+	return new Common::SeekableSubReadStream(&file, offsets[id - 1], offsets[id]);
 }
 
 
diff --git a/engines/teenagent/pack.h b/engines/teenagent/pack.h
index 53fdf80d33..753941673c 100644
--- a/engines/teenagent/pack.h
+++ b/engines/teenagent/pack.h
@@ -46,6 +46,7 @@ public:
 	virtual Common::SeekableReadStream *getStream(uint32 id) const = 0;
 };
 
+///FilePack keeps opened file and returns substream for each request.
 class FilePack : public Pack {
 	mutable Common::File file;
 	uint32 *offsets;
@@ -62,6 +63,9 @@ public:
 	virtual Common::SeekableReadStream *getStream(uint32 id) const;
 };
 
+/** Pack file which reopens file each request. Do not keep file descriptor open.
+ ** Useful for minimizing file descriptors opened at the same time. Critical for PSP backend.
+ **/
 class TransientFilePack : public Pack {
 	uint32 *offsets;
 	Common::String _filename;
@@ -78,6 +82,7 @@ public:
 	virtual Common::SeekableReadStream *getStream(uint32 id) const;
 };
 
+///MemoryPack loads whole pack in memory, currently unused.
 class MemoryPack : public Pack {
 	struct Chunk {
 		byte *data;