MFB Reconfigurator

MFB Reconfigurator reconfigures a MFB bus interface from an arbitrary configuration to another arbitrary configuration. This includes changing of ITEM_WIDTH, BLOCK_SIZE, REGION_SIZE and number of REGIONS.

Warning

All of the MFB parameteres (bot RX and TX) are required to be powers of 2.

Architecture

MFB Reconfigurator does not perform all the required transformations at once. Instead it consists of components, which modify partial attributes of the MFB bus. These components are connected to a pipeline to form a full power MFB Reconfigurator.

The components included in the architecture are as follows:

1. MFB Item Reconfigurator

   Is cappable of dividing Items into smaller Items to increase their number or joining multiple Items in one Block to decrease their number.

   ENTITY MFB_ITEM_RECONFIGURATOR IS

   Generics

   Generic	Type	Default	Description
   =====	MFB Configuration	=====	=====
   REGIONS	integer	2
   REGION_SIZE	integer	1
   RX_BLOCK_SIZE	integer	8
   TX_BLOCK_SIZE	integer	8
   RX_ITEM_WIDTH	integer	32
   META_WIDTH	integer	0
   =====	Others	=====	=====
   DEVICE	string	“ULTRASCALE”	Target device
   TX_ITEM_WIDTH	integer	RX_ITEM_WIDTH*RX_BLOCK_SIZE/TX_BLOCK_SIZE	Derived parameters DO NOT CHANGE!

   Ports

   Port	Type	Mode	Description
   CLK	std_logic	in
   RESET	std_logic	in
   =====	MFB input interface	=====	=====
   RX_DATA	std_logic_vector(REGIONS*REGION_SIZE*RX_BLOCK_SIZE*RX_ITEM_WIDTH-1 downto 0)	in
   RX_META	std_logic_vector(REGIONS*META_WIDTH-1 downto 0)	in
   RX_SOF	std_logic_vector(REGIONS-1 downto 0)	in
   RX_EOF	std_logic_vector(REGIONS-1 downto 0)	in
   RX_SOF_POS	std_logic_vector(REGIONS*max(1,log2(REGION_SIZE))-1 downto 0)	in
   RX_EOF_POS	std_logic_vector(REGIONS*max(1,log2(REGION_SIZE*RX_BLOCK_SIZE))-1 downto 0)	in
   RX_SRC_RDY	std_logic	in
   RX_DST_RDY	std_logic	out
   =====	MFB output interface	=====	=====
   TX_DATA	std_logic_vector(REGIONS*REGION_SIZE*TX_BLOCK_SIZE*TX_ITEM_WIDTH-1 downto 0)	out
   TX_META	std_logic_vector(REGIONS*META_WIDTH-1 downto 0)	out
   TX_SOF	std_logic_vector(REGIONS-1 downto 0)	out
   TX_EOF	std_logic_vector(REGIONS-1 downto 0)	out
   TX_SOF_POS	std_logic_vector(REGIONS*max(1,log2(REGION_SIZE))-1 downto 0)	out
   TX_EOF_POS	std_logic_vector(REGIONS*max(1,log2(REGION_SIZE*TX_BLOCK_SIZE))-1 downto 0)	out
   TX_SRC_RDY	std_logic	out
   TX_DST_RDY	std_logic	in

2. MFB Block Reconfigurator

   Division of Blocks into smaller Blocks — the division is only done between Items; the component cannot split Items — or joining of multiple Blocks within the same Region into bigger Blocks.

   ENTITY MFB_BLOCK_RECONFIGURATOR IS

   Generics

   Generic	Type	Default	Description
   =====	MFB Configuration	=====	INEFFICIENCY WARNING (for FRAME_ALIGN == 0): When RX_REGION_SIZE > TX_REGION_SIZE all TX Frames are generated with SOF aligned to Region. Might decrease throughput due to unnessesary gaps.
   REGIONS	integer	2
   RX_REGION_SIZE	integer	1
   TX_REGION_SIZE	integer	2
   RX_BLOCK_SIZE	integer	8
   ITEM_WIDTH	integer	32
   META_WIDTH	integer	0
   =====	Others	=====	=====
   META_MODE	integer	0	Metadata validity mode 0 -> with SOF 1 -> with EOF
   FIFO_SIZE	integer	32	Input FIFO size (in number of MFB words) Only applies when RX_REGION_SIZE > TX_REGION_SIZE
   FRAME_ALIGN	integer	0	Frame alignment mode (Only applies when RX_REGION_SIZE > TX_REGION_SIZE) 0 - align to start of Region 1 - align to start of Block (ONLY SUPPORTED WHEN ALL FRAMES ARE BIGGER THAN TX MFB BLOCK)
   DEVICE	string	“ULTRASCALE”	Target device
   TX_BLOCK_SIZE	integer	RX_BLOCK_SIZE*RX_REGION_SIZE/TX_REGION_SIZE	Derived parameters DO NOT CHANGE!

   Ports

   Port	Type	Mode	Description
   CLK	std_logic	in
   RESET	std_logic	in
   =====	MFB input interface	=====	=====
   RX_DATA	std_logic_vector(REGIONS*RX_REGION_SIZE*RX_BLOCK_SIZE*ITEM_WIDTH-1 downto 0)	in
   RX_META	std_logic_vector(REGIONS*META_WIDTH-1 downto 0)	in
   RX_SOF	std_logic_vector(REGIONS-1 downto 0)	in
   RX_EOF	std_logic_vector(REGIONS-1 downto 0)	in
   RX_SOF_POS	std_logic_vector(REGIONS*max(1,log2(RX_REGION_SIZE))-1 downto 0)	in
   RX_EOF_POS	std_logic_vector(REGIONS*max(1,log2(RX_REGION_SIZE*RX_BLOCK_SIZE))-1 downto 0)	in
   RX_SRC_RDY	std_logic	in
   RX_DST_RDY	std_logic	out
   =====	MFB output interface	=====	=====
   TX_DATA	std_logic_vector(REGIONS*TX_REGION_SIZE*TX_BLOCK_SIZE*ITEM_WIDTH-1 downto 0)	out
   TX_META	std_logic_vector(REGIONS*META_WIDTH-1 downto 0)	out
   TX_SOF	std_logic_vector(REGIONS-1 downto 0)	out
   TX_EOF	std_logic_vector(REGIONS-1 downto 0)	out
   TX_SOF_POS	std_logic_vector(REGIONS*max(1,log2(TX_REGION_SIZE))-1 downto 0)	out
   TX_EOF_POS	std_logic_vector(REGIONS*max(1,log2(TX_REGION_SIZE*TX_BLOCK_SIZE))-1 downto 0)	out
   TX_SRC_RDY	std_logic	out
   TX_DST_RDY	std_logic	in

3. MFB Region Reconfigurator

   Division of Regions into smaller Regions — the division is only done between Blocks; the component cannot split Blocks — or joining of multiple Regions within the word into bigger Regions.

   ENTITY MFB_REGION_RECONFIGURATOR IS

   Generics

   Generic	Type	Default	Description
   =====	MFB Configuration	=====	INEFFICIENCY WARNING (for FRAME_ALIGN == 0): When TX_REGIONS < RX_REGIONS all TX Frames are generated with SOF aligned to start of a Region. This might decrease throughput due to unnessesary gaps.
   RX_REGIONS	integer	2
   TX_REGIONS	integer	1
   RX_REGION_SIZE	integer	1
   BLOCK_SIZE	integer	8
   ITEM_WIDTH	integer	32
   META_WIDTH	integer	0
   =====	Others	=====	=====
   META_MODE	integer	0	Metadata validity mode 0 -> with SOF 1 -> with EOF
   FIFO_SIZE	integer	32	Input FIFO size (in number of MFB words) Only applies when RX_REGIONS > TX_REGIONS
   FRAME_ALIGN	integer	0	Frame alignment mode (Only applies when TX_REGIONS < RX_REGIONS) 0 - align to start of Region (requires more resources) 1 - align to start of Block (ONLY SUPPORTED WHEN ALL FRAMES ARE BIGGER THAN TX MFB REGION)
   DEVICE	string	“ULTRASCALE”	Target device
   TX_REGION_SIZE	integer	RX_REGION_SIZE*RX_REGIONS/TX_REGIONS	Derived parameters DO NOT CHANGE!

   Ports

   Port	Type	Mode	Description
   =====	Clock and Reset	=====	=====
   CLK	std_logic	in
   RESET	std_logic	in
   =====	MFB input interface	=====	=====
   RX_DATA	std_logic_vector(RX_REGIONS*RX_REGION_SIZE*BLOCK_SIZE*ITEM_WIDTH-1 downto 0)	in
   RX_META	std_logic_vector(RX_REGIONS*META_WIDTH-1 downto 0)	in
   RX_SOF	std_logic_vector(RX_REGIONS-1 downto 0)	in
   RX_EOF	std_logic_vector(RX_REGIONS-1 downto 0)	in
   RX_SOF_POS	std_logic_vector(RX_REGIONS*max(1,log2(RX_REGION_SIZE))-1 downto 0)	in
   RX_EOF_POS	std_logic_vector(RX_REGIONS*max(1,log2(RX_REGION_SIZE*BLOCK_SIZE))-1 downto 0)	in
   RX_SRC_RDY	std_logic	in
   RX_DST_RDY	std_logic	out
   =====	MFB output interface	=====	=====
   TX_DATA	std_logic_vector(TX_REGIONS*TX_REGION_SIZE*BLOCK_SIZE*ITEM_WIDTH-1 downto 0)	out
   TX_META	std_logic_vector(TX_REGIONS*META_WIDTH-1 downto 0)	out
   TX_SOF	std_logic_vector(TX_REGIONS-1 downto 0)	out
   TX_EOF	std_logic_vector(TX_REGIONS-1 downto 0)	out
   TX_SOF_POS	std_logic_vector(TX_REGIONS*max(1,log2(TX_REGION_SIZE))-1 downto 0)	out
   TX_EOF_POS	std_logic_vector(TX_REGIONS*max(1,log2(TX_REGION_SIZE*BLOCK_SIZE))-1 downto 0)	out
   TX_SRC_RDY	std_logic	out
   TX_DST_RDY	std_logic	in

4. MFB Transformer

It is important to realize, that the components cannot be placed in the MFB Reconfigurator in an arbitrary order. In fact, as you can see in the diagram above, all of them appart from the MFB Transformer are required to be present twice. One of the 2 copies is needed when division is being done; the other when joining is done. The means, that there is allways one of these 2 copies, which is not needed, and is reduced to simple straight RX-to-TX connection. For example: when the ITEM_WIDTH is being lowered, the first copy of Item Reconfigurator is used to divide Items into smaller Items, while the second copy is not needed. When the ITEM_WIDTH is being increased, it is the other way around. If the respective MFB parameter is not changing at all, neither of the 2 copies are needed and both are reduced to straight conenctions. (If the RX MFB configuration is the same as the TX MFB configuration, the whole component is reduced to straight signal connections.)

The reason for this are the constraints, which each of the components has in order to work. For example: Let’s say you have a MFB bus with 2 MFB Regions, 2 MFB Blocks each, 2 MFB Items each, 8 bits wide each (configuration (2,2,2,8)). And you want to reconfigure this but into a single MFB Item 128 bits wide (1,1,1,128). Since the original bus was only 2*2*2*8 = 64 bits wide, you will need MFB Transformer to increase the word size. At the same time you cannot perform any transformations before the word is resized, because neither Items Reconfigurator, nor Block Reconfigurator, nor Region Reconfigurator can create an Item / BLock / Region, which is wider than the whole current word. This means, that the first 3 components will actualy be removed and the pipeline will start with the MFB Transformer.

Constraints and side-effects

The MFB Reconfigurator has a few constraints and side-effects concerning secondary MFB bus characteristics.

First there are side-effects caused by the very nature of the MFB bus:

If you are increasing the value ITEM_WIDTH, you are reducing the resolution of the EOF_POS value. This in turn means that you are reducing the resolution of the frame length information. In that case, Item Reconfigurator round the value of EOF_POS up, which will lead to invalid data appearing at the end of each previously unaligned frame. (e.g.: If there is a frame with the size of 1 MFB Item and we are doubling the ITEM_WIDTH, then the output frame will also have the size of 1 MFB Item, but it will be a larger MFB Item and only the beginig will contain valid data.)

Data shifting

Some reconfigurations will require shifting of frame data within the data word. Data shifting is the most resource-consuming action of the MFB Reconfigurator. It also raises the component latency and, in case of a complicated MFB configuration, may lead to timing problems. Data shifting in the MFB Reconfigurator occurs when either of these two operations are required:

1. Blocks are being merged together (BLOCK_SIZE * ITEM_WIDTH is being increased).

2. Reginos are being merged together (REGION_SIZE * BLOCK_SIZE * ITEM_WIDTH is being increased).

In these two cases, a situation may occur, when multiple SOFs or EOFs occur in the same Region after the reconfiguration. This is not allowed on the MFB bus and data shifting is thus required. The user can prevent this by declaring, that such situation will not occur on the data bus using generics FRAMES_OVER_TX_BLOCK and FRAMES_OVER_TX_REGION respectively.

When data shifting is required, the MFB Reconfigurator does not support shared Regions for TX MFB. (TX MFB interface will not contain any Regions with data from 2 different frames.) This is done in sake of logic complexity and implementation difficulty reduction. When data is being shifted, each output data block is dependent on all previous input data blocks. To support shared output Regions, the logic would also have to check for presence of double SOF or EOF in the output Region, which would add dependency on all othee output Blocks in the same Region.