SuperStrict
Import BRL.BankStream
Import BRL.Stream
Import "lzma.bmx"
Rem
bbdoc: LZMA stream wrapper type
about:
#TLzmaStream wraps a raw stream and allows access to uncompressed data.
When writing, the data is compressed and the compressed daa written to the wrapped stream.
If compression expands the data, uncompressed data is written instead.
Changes in the raw stream don't automatically appear in a TLzmaStream
- #ReadSync updates to the current raw stream, but any changes are lost.
Similarly, changes written to a TLzmaStream are only written to the raw stream
on a Flush/FlushStream call or when the stream is closed.
Note: You may lose data if you fail to close/flush the stream before program ends.
Do not rely on the automatic Delete->Close call!
End Rem
Type TLzmaStream Extends TStreamWrapper
Field _basestream:TStream
Field _level:Int = 5
Rem
bbdoc: Closes the stream, writing any changes
End Rem
Method Close()
Flush()
_basestream.Close()
_stream.Close()
End Method
Rem
bbdoc: Updates to current raw stream data
End Rem
Method ReadSync()
'Empty stream?
If _basestream.Size()=0
_stream = CreateBankStream(Null)
Return
End If
'Copy stream contents to a bank
Local b:TBank = CreateBank(_basestream.Size())
CopyStream _basestream, CreateBankStream(b)
'Set up bank for raw access
Local buf:Byte Ptr = b.Lock()
Local size:Int = b.Size()-4
'Is this uncompressed data?
Local usize:Int = Int Ptr(buf)[0] + 1
If usize<=1
Local u:TBank = CreateBank(-usize)
Local ubuf:Byte Ptr = u.Lock()
MemCopy ubuf, buf+4, -usize
u.Unlock()
_stream = CreateBankStream(u)
Return
End If
'Create a bank for uncompressed data
Local u:TBank = CreateBank(usize)
Local ubuf:Byte Ptr = u.Lock()
LzmaUncompress ubuf, usize, buf+4, size
'Not valid LZMA?
If usize <> u.Size()-1 Then Return
u.Unlock()
u.Resize(usize)
_stream = CreateBankStream(u)
End Method
Rem
bbdoc: Flushes current data to the raw stream
End Rem
Method Flush()
'Set up bank for raw access
Local b:TBank = TBankStream(_stream)._bank
Local bsize:Int = b.Size()
Local buf:Byte Ptr = b.Lock()
'Create bank for compressed data
Local csize:Int = bsize + 1024
Local c:TBank = CreateBank(csize)
Local cbuf:Byte Ptr = c.Lock()
LzmaCompress2 cbuf, csize, buf, bsize, _level
_basestream.Seek 0
'Does it fit?
If csize<b.Size()
_basestream.WriteInt b.Size()
_basestream.WriteBytes cbuf, csize
Else
'Write uncompressed
_basestream.WriteInt -b.Size()
_basestream.WriteBytes buf, b.Size()
End If
b.Unlock()
End Method
Function Create:TLzmaStream( stream:TStream )
'Stream must be seekable
If stream=Null Or stream.Seek(0)=-1 Then Return Null
Local l:TLzmaStream = New TLzmaStream
l._basestream = stream
l.ReadSync()
If Not l._stream Then Return Null
Return l
End Function
End Type
Rem
bbdoc: Opens #url as TLzmaStream
about:
An alternative to using OpenStream("lzma::-blah").
End Rem
Function CreateLzmaStream:TLzmaStream( url:Object )
Return TLzmaStream.Create( OpenStream(url) )
End Function
New TLzmaStreamFactory
Type TLzmaStreamFactory Extends TStreamFactory
Method CreateStream:TStream( url:Object,proto$,path$,readable%,writeable% )
If proto<>"lzma" Then Return Null
Local stream:TStream = OpenStream(path)
Assert stream<>Null
Return TLzmaStream.Create( stream )
End Method
End Type |
