PCIe Packet Writer

ENTITY PCIE_PKT_WRITER IS

Basic description (more information in README)

This module accepts packets and the address to which it shall be written into memory. It splits packets according to the PCIe MTU and memory page boundaries. Then it generates an Upstream DMA header for each of these packet parts. Its output interface is compatible with the PTC module.

Input packets are expected to start at the beginning of the word (Item 0).

Check out this diagram for a top-level view of the PCIe Packet Writer’s architecture.

Generics

Generic	Type	Default	Description
=====	MFB parameters	=====	=====
MFB_REGIONS	natural	1	Number of MFB Regions in a word, cannot handle more than 1.
MFB_REGION_SIZE	natural	8
MFB_BLOCK_SIZE	natural	8
MFB_ITEM_WIDTH	natural	8
=====	Other parameters	=====	=====
PKT_MTU	integer	2**12	Maximum packet size (in bytes).
PCIE_MPS_WIDTH	integer	15
ADDRESS_WIDTH	natural	64
PAGE_SIZE	natural	4096	Size of a RAM page (in bytes). Must be a power of two.
DEVICE	string	“AGILEX”

Ports

Port	Type	Mode	Description
CLK	std_logic	in
RESET	std_logic	in
PCIE_MPS	std_logic_vector(PCIE_MPS_WIDTH-1 downto 0)	in	Specifies the currently configured max PCIe write request (in bytes). PCIe specification allows at least 128.
=====	RX Interface	=====	=====
RX_MVB_ADDRESS	std_logic_vector(MFB_REGIONS*ADDRESS_WIDTH-1 downto 0)	in
RX_MVB_LENGTH	std_logic_vector(MFB_REGIONS*log2(PKT_MTU+1)-1 downto 0)	in
RX_MVB_VLD	std_logic_vector(MFB_REGIONS-1 downto 0)	in
RX_MVB_SRC_RDY	std_logic	in
RX_MVB_DST_RDY	std_logic	out
RX_MFB_DATA	std_logic_vector(MFB_REGIONS*MFB_REGION_SIZE*MFB_BLOCK_SIZE*MFB_ITEM_WIDTH-1 downto 0)	in
RX_MFB_SOF	std_logic_vector(MFB_REGIONS-1 downto 0)	in
RX_MFB_EOF	std_logic_vector(MFB_REGIONS-1 downto 0)	in
RX_MFB_SOF_POS	std_logic_vector(MFB_REGIONS*max(1,log2(MFB_REGION_SIZE))-1 downto 0)	in
RX_MFB_EOF_POS	std_logic_vector(MFB_REGIONS*max(1,log2(MFB_REGION_SIZE*MFB_BLOCK_SIZE))-1 downto 0)	in
RX_MFB_SRC_RDY	std_logic	in
RX_MFB_DST_RDY	std_logic	out
=====	TX Interface	=====	=====
TX_MVB_DATA	std_logic_vector(MFB_REGIONS*DMA_UPHDR_WIDTH-1 downto 0)	out	Contains DMA Upstream header
TX_MVB_VLD	std_logic_vector(MFB_REGIONS-1 downto 0)	out
TX_MVB_SRC_RDY	std_logic	out
TX_MVB_DST_RDY	std_logic	in
TX_MFB_DATA	std_logic_vector(MFB_REGIONS*MFB_REGION_SIZE*MFB_BLOCK_SIZE*MFB_ITEM_WIDTH-1 downto 0)	out
TX_MFB_SOF	std_logic_vector(MFB_REGIONS-1 downto 0)	out
TX_MFB_EOF	std_logic_vector(MFB_REGIONS-1 downto 0)	out
TX_MFB_SOF_POS	std_logic_vector(MFB_REGIONS*max(1,log2(MFB_REGION_SIZE))-1 downto 0)	out
TX_MFB_EOF_POS	std_logic_vector(MFB_REGIONS*max(1,log2(MFB_REGION_SIZE*MFB_BLOCK_SIZE))-1 downto 0)	out
TX_MFB_SRC_RDY	std_logic	out
TX_MFB_DST_RDY	std_logic	in

Architecture

Top-level architecture of the PCIe Packet Writer component