Namespace std.memory

Using std.stream

#rem monkeydoc DataBuffer class.
#end
Class DataBuffer

	#rem monkeydoc Creates a new databuffer.
	
	The new databuffer initally uses little endian byte order. You can change this via the ByteOrder property.
	
	@example
	
	\#Import "<std>"
	
	Using std.memory
	
	Function Main()

		Local buf:=New DataBuffer( 10 )
		
		Print buf.Length
	
		For Local i:=0 Until 10
			buf.PokeByte( i,i*2 )
		Next
		
		For Local i:=0 Until 10
			Print buf.PeekByte( i )
		Next
		
	End
	
	@end
	
	@param length The length of the databuffer to create, in bytes.
	
	#end
	Method New( length:Int )
		_length=length
		_data=Cast<UByte Ptr>( libc.malloc( length ) )
		_byteOrder=ByteOrder.LittleEndian
		_swapEndian=False
	End
	
	#rem monkeydoc Frees the databuffer's internal memory.
	
	Once discarded, a databuffer's length is set to 0.
	
	#end
	Method Discard()
		libc.free( _data )
		_data=Null
		_length=0
	End
	
	#rem monkeydoc A raw pointer to the databuffer's internal memory.
	
	Note: This pointer will change if the databuffer is resized using Resize.
	
	#end
	Property Data:UByte Ptr()
		Return _data
	End
	
	#rem monkeydoc The length of the databuffer in bytes.
	#end
	Property Length:Int()
		Return _length
	End
	
	#rem monkeydoc The byte order of the databuffer.
	#end
	Property ByteOrder:ByteOrder()
		Return _byteOrder
	Setter( byteOrder:ByteOrder )
		_byteOrder=byteOrder
		_swapEndian=(_byteOrder=ByteOrder.BigEndian)
	End

	#rem monkeydoc Resizes the databuffer.
	
	Note: This method reallocates the internal memory buffer and will cause the Data property to change.
	
	@param length The new length of the databuffer.
	
	#end	
	Method Resize( length:Int )
		Local data:=Cast<UByte Ptr>( libc.malloc( length ) )
		libc.memcpy( data,_data,Min( length,_length ) )
		libc.free( _data )
		_data=data
	End
	
	#rem monkeydoc Reads a byte from the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to read.
	
	#return The byte read from `offset`.
	
	#end
	Method PeekByte:Byte( offset:Int )
		DebugAssert( offset>=0 And offset<_length )
		
		Return Cast<Byte Ptr>( _data+offset )[0]
	End
	
	#rem monkeydoc Reads a ubyte from the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to read.
	
	#return The ubyte read from `offset`.
	
	#end
	Method PeekUByte:UByte( offset:Int )
		DebugAssert( offset>=0 And offset<_length )

		Return Cast<UByte Ptr>( _data+offset )[0]
	End
	
	#rem monkeydoc Reads a 16 bit short from the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to read.
	
	#return The short read from `offset`.
	
	#end
	Method PeekShort:Short( offset:Int )
		DebugAssert( offset>=0 And offset<_length-1 )
		
		Local t:=Cast<Short Ptr>( _data+offset )[0]
		If _swapEndian Swap2( Varptr t )
		Return t
	End
	
	#rem monkeydoc Reads a 16 bit ushort from the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to read.
	
	#return The ushort read from `offset`.
	
	#end
	Method PeekUShort:UShort( offset:Int )
		DebugAssert( offset>=0 And offset<_length-1 )

		Local t:=Cast<UShort Ptr>( _data+offset )[0]
		If _swapEndian Swap2( Varptr t )
		Return t
	End
	
	#rem monkeydoc Reads a 32 bit int from the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to read.
	
	#return The int read from `offset`.
	
	#end
	Method PeekInt:Int( offset:Int )
		DebugAssert( offset>=0 And offset<_length-3 )
	
		Local t:=Cast<Int Ptr>( _data+offset )[0]
		If _swapEndian Swap4( Varptr t )
		Return t
	End
	
	#rem monkeydoc Reads a 32 bit uint from the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to read.
	
	#return The uint read from `offset`.
	
	#end
	Method PeekUInt:UInt( offset:Int )
		DebugAssert( offset>=0 And offset<_length-3 )

		Local t:=Cast<UInt Ptr>( _data+offset )[0]
		If _swapEndian Swap4( Varptr t )
		Return t
	End
	
	#rem monkeydoc Reads a 64 bit long from the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to read.
	
	#return The long read from `offset`.
	
	#end
	Method PeekLong:Long( offset:Int )
		DebugAssert( offset>=0 And offset<_length-7 )
		
		Local t:=Cast<Long Ptr>( _data+offset )[0]
		If _swapEndian Swap8( Varptr t )
		Return t
	End
		
	#rem monkeydoc Reads a 64 bit ulong from the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to read.
	
	#return The ulong read from `offset`.
	
	#end
	Method PeekULong:ULong( offset:Int )
		DebugAssert( offset>=0 And offset<_length-7 )

		Local t:=Cast<ULong Ptr>( _data+offset )[0]
		If _swapEndian Swap8( Varptr t )
		Return t
	End
	
	#rem monkeydoc Reads a 32 bit float from the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to read.
	
	#return The float read from `offset`.
	
	#end
	Method PeekFloat:Float( offset:Int )
		DebugAssert( offset>=0 And offset<_length-3 )

		Local t:=Cast<Float Ptr>( _data+offset )[0]
		If _swapEndian Swap4( Varptr t )
		Return t
	End
	
	#rem monkeydoc Reads a 64 bit double from the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to read.
	
	#return The double read from `offset`.
	
	#end
	Method PeekDouble:Double( offset:Int )
		DebugAssert( offset>=0 And offset<_length-7 )
	
		Local t:=Cast<Double Ptr>( _data+offset )[0]
		If _swapEndian Swap8( Varptr t )
		Return t
	End
	
	#rem monkeydoc Writes a byte to the databuffer
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to write.
	
	#end
	Method PokeByte( offset:Int,value:Byte )
		DebugAssert( offset>=0 And offset<_length )
	
		Cast<Byte Ptr>( _data+offset )[0]=value
	End
	
	#rem monkeydoc Writes an unsigned byte to the databuffer.
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to write.
	
	#end
	Method PokeUByte( offset:Int,value:UByte )
		DebugAssert( offset>=0 And offset<_length )

		Cast<UByte Ptr>( _data+offset )[0]=value
	End
	
	#rem monkeydoc Writes a 16 bit short to the databuffer
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to write.
	
	#end
	Method PokeShort( offset:Int,value:Short )
		DebugAssert( offset>=0 And offset<_length-1 )
	
		If _swapEndian Swap2( Varptr value )
		Cast<Short Ptr>( _data+offset )[0]=value
	End
	
	#rem monkeydoc Writes a 16 bit unsigned short to the databuffer
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to write.
	
	#end
	Method PokeUShort( offset:Int,value:UShort )
		DebugAssert( offset>=0 And offset<_length-1 )

		If _swapEndian Swap2( Varptr value )
		Cast<UShort Ptr>( _data+offset )[0]=value
	End
	
	#rem monkeydoc Writes a 32 bit int to the databuffer
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to write.
	
	#end
	Method PokeInt( offset:Int,value:Int )
		DebugAssert( offset>=0 And offset<_length-3 )
	
		If _swapEndian Swap4( Varptr value )
		Cast<Int Ptr>( _data+offset )[0]=value
	End
	
	#rem monkeydoc Writes a 32 bit unsigned int to the databuffer
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to write.
	
	#end
	Method PokeUInt( offset:Int,value:UInt )
		DebugAssert( offset>=0 And offset<_length-3 )

		If _swapEndian Swap4( Varptr value )
		Cast<UInt Ptr>( _data+offset )[0]=value
	End
	
	#rem monkeydoc Writes a 64 bit long to the databuffer
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to write.
	
	#end
	Method PokeLong( offset:Int,value:Long )
		DebugAssert( offset>=0 And offset<_length-7 )

		If _swapEndian Swap8( Varptr value )
		Cast<Long Ptr>( _data+offset )[0]=value
	End
	
	#rem monkeydoc Writes a 64 bit unsigned long to the databuffer
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to write.
	
	#end
	Method PokeULong( offset:Int,value:ULong )
		DebugAssert( offset>=0 And offset<_length-7 )
		
		If _swapEndian Swap8( Varptr value )
		Cast<ULong Ptr>( _data+offset )[0]=value
	End
	
	#rem monkeydoc Writes a 32 bit float to the databuffer
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to write.
	
	#end
	Method PokeFloat( offset:Int,value:Float )
		DebugAssert( offset>=0 And offset<_length-3 )
	
		If _swapEndian Swap4( Varptr value )
		Cast<Float Ptr>( _data+offset )[0]=value
	End
	
	#rem monkeydoc Writes a 64 bit double to the databuffer
	
	In debug builds, a runtime error will occur if `offset` is outside the range of the databuffer.
	
	#param offset The offset to write.
	
	#end
	Method PokeDouble( offset:Int,value:Double )
		DebugAssert( offset>=0 And offset<_length-7 )
	
		If _swapEndian Swap8( Varptr value )
		Cast<Double Ptr>( _data+offset )[0]=value
	End
	
	#rem monkeydoc Copies databuffer data.
	
	In debug builds, a runtime error while occur if an attempt it made to copy data outside the range of either databuffer.
	
	@param dst The destination databuffer.
	
	@param srcOffset The starting byte offset in this databuffer to copy from.
	
	@param dstOffset The starting byte offest in the destination databuffer to copy to.
	
	@param count The number of bytes to copy.
	
	#end
	Method CopyTo( dst:DataBuffer,srcOffset:Int,dstOffset:Int,count:Int )
		DebugAssert( srcOffset>=0 And srcOffset+count<=_length And dstOffset>=0 And dstOffset+count<=dst._length )
		
		libc.memmove( dst._data+dstOffset,_data+srcOffset,count )
	End
	
	#rem monkeydoc Saves the contents of the databuffer to a file.
	
	@param path The file path.
	
	@return True if successful, false if `path` could not be opened or not all data could be written.
	
	#end
	Method Save:Bool( path:String )
	
		Local stream:=Stream.Open( path,"w" )
		If Not stream Return False
		
		Local n:=stream.Write( _data,_length )
		
		stream.Close()
		
		Return n=_length
	End
	
	#rem monkeydoc Creates a databuffer with the contents of a file.
	
	@param path The file path.
	
	@return A new databuffer containing the contents of `path`, or null if `path` could not be opened.
	
	#end
	Function Load:DataBuffer( path:String )
	
		Local stream:=Stream.Open( path,"r" )
		If Not stream Return Null
		
		Local length:=stream.Length
		Local buf:=New DataBuffer( length )
		stream.Read( buf.Data,length )
		
		stream.Close()
		Return buf
	End

	Private
	
	Field _data:UByte Ptr
	Field _length:Int
	Field _byteOrder:ByteOrder
	Field _swapEndian:Bool
	
	Function Swap2( v:Void Ptr )
		Local t:=Cast<UShort Ptr>( v )[0]
		Cast<UShort Ptr>( v )[0]=(t Shr 8 & $ff) | (t & $ff) Shl 8
	End
	
	Function Swap4( v:Void Ptr )
		Local t:=Cast<UInt Ptr>( v )[0]
		Cast<UInt Ptr>( v )[0]=(t Shr 24 & $ff) | (t & $ff) Shl 24 | (t Shr 8 & $ff00) | (t & $ff00) Shl 8
	End
	
	Function Swap8( v:Void Ptr )
		Local t:=Cast<ULong Ptr>( v )[0]
		Cast<ULong Ptr>( v )[0]=(t Shr 56 & $ff) | (t & $ff) Shl 56 | (t Shr 40 & $ff00) | (t & $ff00) Shl 40 | (t Shr 24 & $ff0000) | (t & $ff0000) Shl 24 | (t Shr 8 & $ff000000) | (t & $ff000000) Shl 8
	End

End