// (C) 2001-2013 Altera Corporation. All rights reserved.
// Your use of Altera Corporation's design tools, logic functions and other
// software and tools, and its AMPP partner logic functions, and any output
// files any of the foregoing (including device programming or simulation
// files), and any associated documentation or information are expressly subject
// to the terms and conditions of the Altera Program License Subscription
// Agreement, Altera MegaCore Function License Agreement, or other applicable
// license agreement, including, without limitation, that your use is for the
// sole purpose of programming logic devices manufactured by Altera and sold by
// Altera or its authorized distributors. Please refer to the applicable
// agreement for further details.
// (C) 2001-2012 Altera Corporation. All rights reserved.
// Your use of Altera Corporation's design tools, logic functions and other
// software and tools, and its AMPP partner logic functions, and any output
// files any of the foregoing (including device programming or simulation
// files), and any associated documentation or information are expressly subject
// to the terms and conditions of the Altera Program License Subscription
// Agreement, Altera MegaCore Function License Agreement, or other applicable
// license agreement, including, without limitation, that your use is for the
// sole purpose of programming logic devices manufactured by Altera and sold by
// Altera or its authorized distributors. Please refer to the applicable
// agreement for further details.
// $Id: //acds/rel/13.0sp1/ip/merlin/altera_merlin_slave_agent/altera_merlin_burst_uncompressor.sv#1 $
// $Revision: #1 $
// $Date: 2013/03/07 $
// $Author: swbranch $
// ------------------------------------------
// Merlin Burst Uncompressor
//
// Compressed read bursts -> uncompressed
// ------------------------------------------
`timescale 1 ns / 1 ns
module altera_merlin_burst_uncompressor
#(
parameter ADDR_W = 16,
parameter BURSTWRAP_W = 3,
parameter BYTE_CNT_W = 4,
parameter PKT_SYMBOLS = 4,
parameter BURST_SIZE_W = 3
)
(
input clk,
input reset,
// sink ST signals
input sink_startofpacket,
input sink_endofpacket,
input sink_valid,
output sink_ready,
// sink ST "data"
input [ADDR_W - 1: 0] sink_addr,
input [BURSTWRAP_W - 1 : 0] sink_burstwrap,
input [BYTE_CNT_W - 1 : 0] sink_byte_cnt,
input sink_is_compressed,
input [BURST_SIZE_W-1 : 0] sink_burstsize,
// source ST signals
output source_startofpacket,
output source_endofpacket,
output source_valid,
input source_ready,
// source ST "data"
output [ADDR_W - 1: 0] source_addr,
output [BURSTWRAP_W - 1 : 0] source_burstwrap,
output [BYTE_CNT_W - 1 : 0] source_byte_cnt,
// Note: in the slave agent, the output should always be uncompressed. In
// other applications, it may be required to leave-compressed or not. How to
// control? Seems like a simple mux - pass-through if no uncompression is
// required.
output source_is_compressed,
output [BURST_SIZE_W-1 : 0] source_burstsize
);
//----------------------------------------------------
// AXSIZE decoding
//
// Turns the axsize value into the actual number of bytes
// being transferred.
// ---------------------------------------------------
function reg[63:0] bytes_in_transfer;
input [2:0] axsize;
case (axsize)
3'b000: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000000001;
3'b001: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000000010;
3'b010: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000000100;
3'b011: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000001000;
3'b100: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000010000;
3'b101: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000100000;
3'b110: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000001000000;
3'b111: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000010000000;
default:bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000000001;
endcase
endfunction
// num_symbols is PKT_SYMBOLS, appropriately sized.
wire [31:0] int_num_symbols = PKT_SYMBOLS;
wire [BYTE_CNT_W-1:0] num_symbols = int_num_symbols[BYTE_CNT_W-1:0];
// def: Burst Compression. In a merlin network, a compressed burst is one
// which is transmitted in a single beat. Example: read burst. In
// constrast, an uncompressed burst (example: write burst) is transmitted in
// one beat per writedata item.
//
// For compressed bursts which require response packets, burst
// uncompression is required. Concrete example: a read burst of size 8
// occupies one response-fifo position. When that fifo position reaches the
// front of the FIFO, the slave starts providing the required 8 readdatavalid
// pulses. The 8 return response beats must be provided in a single packet,
// with incrementing address and decrementing byte_cnt fields. Upon receipt
// of the final readdata item of the burst, the response FIFO item is
// retired.
// Burst uncompression logic provides:
// a) 2-state FSM (idle, busy)
// reset to idle state
// transition to busy state for 2nd and subsequent rdv pulses
// - a single-cycle burst (aka non-burst read) causes no transition to
// busy state.
// b) response startofpacket/endofpacket logic. The response FIFO item
// will have sop asserted, and may have eop asserted. (In the case of
// multiple read bursts transmit in the command fabric in a single packet,
// the eop assertion will come in a later FIFO item.) To support packet
// conservation, and emit a well-formed packet on the response fabric,
// i) response fabric startofpacket is asserted only for the first resp.
// beat;
// ii) response fabric endofpacket is asserted only for the last resp.
// beat.
// c) response address field. The response address field contains an
// incrementing sequence, such that each readdata item is associated with
// its slave-map location. N.b. a) computing the address correctly requires
// knowledge of burstwrap behavior b) there may be no clients of the address
// field, which makes this field a good target for optimization. See
// burst_uncompress_address_counter below.
// d) response byte_cnt field. The response byte_cnt field contains a
// decrementing sequence, such that each beat of the response contains the
// count of bytes to follow. In the case of sub-bursts in a single packet,
// the byte_cnt field may decrement down to num_symbols, then back up to
// some value, multiple times in the packet.
reg burst_uncompress_busy;
reg [BYTE_CNT_W-1:0] burst_uncompress_byte_counter;
wire first_packet_beat;
wire last_packet_beat;
assign first_packet_beat = sink_valid & ~burst_uncompress_busy;
// First cycle: burst_uncompress_byte_counter isn't ready yet, mux the input to
// the output.
assign source_byte_cnt =
first_packet_beat ? sink_byte_cnt : burst_uncompress_byte_counter;
assign source_valid = sink_valid;
// Last packet beat is set throughout receipt of an uncompressed read burst
// from the response FIFO - this forces all the burst uncompression machinery
// idle.
assign last_packet_beat = ~sink_is_compressed |
(
burst_uncompress_busy ?
(sink_valid & (burst_uncompress_byte_counter == num_symbols)) :
sink_valid & (sink_byte_cnt == num_symbols)
);
always @(posedge clk or posedge reset) begin
if (reset) begin
burst_uncompress_busy <= '0;
burst_uncompress_byte_counter <= '0;
end
else begin
if (source_valid & source_ready & sink_valid) begin
// No matter what the current state, last_packet_beat leads to
// idle.
if (last_packet_beat) begin
burst_uncompress_busy <= '0;
burst_uncompress_byte_counter <= '0;
end
else begin
if (burst_uncompress_busy) begin
burst_uncompress_byte_counter <= burst_uncompress_byte_counter ?
(burst_uncompress_byte_counter - num_symbols) :
(sink_byte_cnt - num_symbols);
end
else begin // not busy, at least one more beat to go
burst_uncompress_byte_counter <= sink_byte_cnt - num_symbols;
// To do: should busy go true for numsymbols-size compressed
// bursts?
burst_uncompress_busy <= '1;
end
end
end
end
end
wire [ADDR_W - 1 : 0 ] addr_width_burstwrap;
reg [ADDR_W - 1 : 0 ] burst_uncompress_address_base;
reg [ADDR_W - 1 : 0] burst_uncompress_address_offset;
wire [63:0] decoded_burstsize_wire;
wire [ADDR_W-1:0] decoded_burstsize;
// The input burstwrap value can be used as a mask against address values,
// but with one caveat: the address width may be (probably is) wider than
// the burstwrap width. The spec says: extend the msb of the burstwrap
// value out over the entire address width (but only if the address width
// actually is wider than the burstwrap width; otherwise it's a 0-width or
// negative range and concatenation multiplier).
assign addr_width_burstwrap[BURSTWRAP_W - 1 : 0] = sink_burstwrap;
generate
if (ADDR_W > BURSTWRAP_W) begin : addr_sign_extend
// Sign-extend, just wires:
assign addr_width_burstwrap[ADDR_W - 1 : BURSTWRAP_W] =
{(ADDR_W - BURSTWRAP_W) {sink_burstwrap[BURSTWRAP_W - 1]}};
end
endgenerate
always @(posedge clk or posedge reset) begin
if (reset) begin
burst_uncompress_address_base <= '0;
end
else if (first_packet_beat & source_ready) begin
burst_uncompress_address_base <= sink_addr & ~addr_width_burstwrap;
end
end
assign decoded_burstsize_wire = bytes_in_transfer(sink_burstsize); //expand it to 64 bits
assign decoded_burstsize = decoded_burstsize_wire[ADDR_W-1:0]; //then take the width that is needed
wire [ADDR_W - 1 : 0] p1_burst_uncompress_address_offset =
(
(first_packet_beat ?
sink_addr :
burst_uncompress_address_offset) + decoded_burstsize
) &
addr_width_burstwrap;
always @(posedge clk or posedge reset) begin
if (reset) begin
burst_uncompress_address_offset <= '0;
end
else begin
if (source_ready & source_valid) begin
burst_uncompress_address_offset <= p1_burst_uncompress_address_offset;
// if (first_packet_beat) begin
// burst_uncompress_address_offset <=
// (sink_addr + num_symbols) & addr_width_burstwrap;
// end
// else begin
// burst_uncompress_address_offset <=
// (burst_uncompress_address_offset + num_symbols) & addr_width_burstwrap;
// end
end
end
end
// On the first packet beat, send the input address out unchanged,
// while values are computed/registered for 2nd and subsequent beats.
assign source_addr = first_packet_beat ? sink_addr :
burst_uncompress_address_base | burst_uncompress_address_offset;
assign source_burstwrap = sink_burstwrap;
assign source_burstsize = sink_burstsize;
//-------------------------------------------------------------------
// A single (compressed) read burst will have sop/eop in the same beat.
// A sequence of read sub-bursts emitted by a burst adapter in response to a
// single read burst will have sop on the first sub-burst, eop on the last.
// Assert eop only upon (sink_endofpacket & last_packet_beat) to preserve
// packet conservation.
assign source_startofpacket = sink_startofpacket & ~burst_uncompress_busy;
assign source_endofpacket = sink_endofpacket & last_packet_beat;
assign sink_ready = source_valid & source_ready & last_packet_beat;
// This is correct for the slave agent usage, but won't always be true in the
// width adapter. To do: add an "please uncompress" input, and use it to
// pass-through or modify, and set source_is_compressed accordingly.
assign source_is_compressed = 1'b0;
endmodule
