VisualApplets
Operator Reference

Operator Library: Memory

This operator facilitates the random read of the buffered data. The frame data is transferred into the operator via link I. The random read of the data can be performed by transferring addresses to ports RColA (read column address) and RRowA (read row address). The operator will use the addresses to read the frame data by the given coordinates. The resulting output frame will have the image dimensions of the address inputs. One VisualApplets resource of type RAM is required. Check 'Allocation of Device Resources' for more information. For information on the latency of the operator, see Table 43, 'Individual Latencies of the Operators in Library Memory'.

The FrameBufferRandomRead (frame buffer random read) operator buffers the image stream in the Frame Grabber RAM (DRAM). One VisualApplets resource of type RAM is required.

The operator has two states:

The image data input and the address inputs are not synchronous to each other. They may have different image dimensions. Both address inputs RColA and RRowA have to be O-synchronous.

Please note the timing of the input links. The address inputs must not be sourced by the same operator as the data link input I without buffering. This is because while writing the image data into the operator, no addresses to read the current frame can be accepted. Only if the frame is fully stored into the buffer, addresses can be accepted. In many cases, the operator CreateBlankImage is used to generate the images for the addresses.

The operator uses large non-FPGA memory. If only small frames or lines have to be stored consider using operators FrameMemoryRandomRd or LineMemoryRandomRd.

To measure the fill level of the buffer the operator provides 2 parameters: FillLevel and Overflow. FillLevel shows the percentage fill level of the RAM. The Overflow parameter is set to 1 when FillLevel is close to or is 100% and the next image to be stored in the buffer will exceed the RAM capacity. In case of an overflow, input frames are discarded. Users have to poll for the overflow parameter. As the duration of the overflow state can be very short it is possible that it is in between of a polling cycle of the operator.

Parameter InfiniteSource is used to specify if the operator is directly connected to a camera or is sequenced with other memory operators. Check 'Infinite Sources / Connecting Cameras' for more information.

Bandwidth Optimization

The theoretical bandwidth [bits/second] going through an operator that uses the Frame Grabber RAM (DRAM) is calculated in accord with the following formula:

However, the actual bandwidth is always less than the theoretical bandwidth due to the DRAM efficiency.

The maximum bandwidth going through the operator is reached if the product of Bit Width and Parallelism is equal to the internal RAM Port Width.

	Platform-specific values
	RAM Port Width and System Clock are platform-specific. See Appendix. Device Resources for detailed information on your individual platform.

Supported Link Format

Link Parameter	Input Link I	Input Link RColA	Input Link RRowA	Output Link O
Bit Width	[1, 64]	auto	auto	as I
Arithmetic	{unsigned, signed}	unsigned	unsigned	as I
Parallelism	1	{1, 2}	as RColA	as I
Kernel Columns	[1, Ram Data Width / Bit Width / Kernel Rows]	1	1	as I
Kernel Rows	[1, Ram Data Width / Bit Width / Kernel Columns]	1	1	as I
Img Protocol	VALT_IMAGE2D	as I	as I	as I
Color Format	any	VAF_GRAY	VAF_GRAY	as I
Color Flavor	any	FL_NONE	FL_NONE	as I
Max. Img Width	any	any	as RColA	as RColA
Max. Img Height	any	any	as RColA	as RColA

	The range of the input bit width is: For unsigned inputs: [1, 64] For signed inputs: [2, 64] For unsigned color inputs: [3, 63] For signed color inputs: [6, 63]. The input bit width must not exceed the native ram data width. Check Appendix. Device Resources for more information.
	The bit width of the column address is:
	The bit width of the row address is:
	The parallelism on the address ports has to be set to 2 in order to use the operator in an efficient way.
	I.BitWidth x I.Kernel Columns x I.Kernel Rows <= RamDataWidth.
	I.MaxImgWidth * I.MaxImgHeight must not exceed the available RAM size: 2^RamAddressWidth.