297 lines
13 KiB
Systemverilog
297 lines
13 KiB
Systemverilog
// (C) 2001-2015 Altera Corporation. All rights reserved.
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// Your use of Altera Corporation's design tools, logic functions and other
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// software and tools, and its AMPP partner logic functions, and any output
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// files any of the foregoing (including device programming or simulation
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// files), and any associated documentation or information are expressly subject
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// to the terms and conditions of the Altera Program License Subscription
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// Agreement, Altera MegaCore Function License Agreement, or other applicable
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// license agreement, including, without limitation, that your use is for the
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// sole purpose of programming logic devices manufactured by Altera and sold by
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// Altera or its authorized distributors. Please refer to the applicable
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// agreement for further details.
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// (C) 2001-2012 Altera Corporation. All rights reserved.
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// Your use of Altera Corporation's design tools, logic functions and other
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// software and tools, and its AMPP partner logic functions, and any output
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// files any of the foregoing (including device programming or simulation
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// files), and any associated documentation or information are expressly subject
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// to the terms and conditions of the Altera Program License Subscription
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// Agreement, Altera MegaCore Function License Agreement, or other applicable
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// license agreement, including, without limitation, that your use is for the
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// sole purpose of programming logic devices manufactured by Altera and sold by
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// Altera or its authorized distributors. Please refer to the applicable
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// agreement for further details.
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// $Id: //acds/rel/15.1/ip/merlin/altera_merlin_slave_agent/altera_merlin_burst_uncompressor.sv#1 $
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// $Revision: #1 $
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// $Date: 2015/08/09 $
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// $Author: swbranch $
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// ------------------------------------------
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// Merlin Burst Uncompressor
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//
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// Compressed read bursts -> uncompressed
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// ------------------------------------------
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`timescale 1 ns / 1 ns
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module altera_merlin_burst_uncompressor
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#(
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parameter ADDR_W = 16,
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parameter BURSTWRAP_W = 3,
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parameter BYTE_CNT_W = 4,
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parameter PKT_SYMBOLS = 4,
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parameter BURST_SIZE_W = 3
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)
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(
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input clk,
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input reset,
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// sink ST signals
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input sink_startofpacket,
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input sink_endofpacket,
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input sink_valid,
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output sink_ready,
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// sink ST "data"
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input [ADDR_W - 1: 0] sink_addr,
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input [BURSTWRAP_W - 1 : 0] sink_burstwrap,
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input [BYTE_CNT_W - 1 : 0] sink_byte_cnt,
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input sink_is_compressed,
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input [BURST_SIZE_W-1 : 0] sink_burstsize,
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// source ST signals
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output source_startofpacket,
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output source_endofpacket,
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output source_valid,
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input source_ready,
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// source ST "data"
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output [ADDR_W - 1: 0] source_addr,
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output [BURSTWRAP_W - 1 : 0] source_burstwrap,
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output [BYTE_CNT_W - 1 : 0] source_byte_cnt,
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// Note: in the slave agent, the output should always be uncompressed. In
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// other applications, it may be required to leave-compressed or not. How to
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// control? Seems like a simple mux - pass-through if no uncompression is
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// required.
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output source_is_compressed,
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output [BURST_SIZE_W-1 : 0] source_burstsize
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);
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//----------------------------------------------------
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// AXSIZE decoding
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//
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// Turns the axsize value into the actual number of bytes
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// being transferred.
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// ---------------------------------------------------
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function reg[63:0] bytes_in_transfer;
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input [BURST_SIZE_W-1:0] axsize;
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case (axsize)
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4'b0000: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000000001;
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4'b0001: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000000010;
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4'b0010: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000000100;
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4'b0011: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000001000;
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4'b0100: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000010000;
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4'b0101: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000100000;
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4'b0110: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000001000000;
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4'b0111: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000010000000;
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4'b1000: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000100000000;
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4'b1001: bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000001000000000;
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default:bytes_in_transfer = 64'b0000000000000000000000000000000000000000000000000000000000000001;
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endcase
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endfunction
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// num_symbols is PKT_SYMBOLS, appropriately sized.
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wire [31:0] int_num_symbols = PKT_SYMBOLS;
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wire [BYTE_CNT_W-1:0] num_symbols = int_num_symbols[BYTE_CNT_W-1:0];
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// def: Burst Compression. In a merlin network, a compressed burst is one
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// which is transmitted in a single beat. Example: read burst. In
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// constrast, an uncompressed burst (example: write burst) is transmitted in
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// one beat per writedata item.
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//
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// For compressed bursts which require response packets, burst
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// uncompression is required. Concrete example: a read burst of size 8
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// occupies one response-fifo position. When that fifo position reaches the
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// front of the FIFO, the slave starts providing the required 8 readdatavalid
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// pulses. The 8 return response beats must be provided in a single packet,
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// with incrementing address and decrementing byte_cnt fields. Upon receipt
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// of the final readdata item of the burst, the response FIFO item is
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// retired.
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// Burst uncompression logic provides:
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// a) 2-state FSM (idle, busy)
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// reset to idle state
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// transition to busy state for 2nd and subsequent rdv pulses
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// - a single-cycle burst (aka non-burst read) causes no transition to
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// busy state.
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// b) response startofpacket/endofpacket logic. The response FIFO item
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// will have sop asserted, and may have eop asserted. (In the case of
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// multiple read bursts transmit in the command fabric in a single packet,
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// the eop assertion will come in a later FIFO item.) To support packet
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// conservation, and emit a well-formed packet on the response fabric,
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// i) response fabric startofpacket is asserted only for the first resp.
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// beat;
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// ii) response fabric endofpacket is asserted only for the last resp.
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// beat.
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// c) response address field. The response address field contains an
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// incrementing sequence, such that each readdata item is associated with
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// its slave-map location. N.b. a) computing the address correctly requires
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// knowledge of burstwrap behavior b) there may be no clients of the address
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// field, which makes this field a good target for optimization. See
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// burst_uncompress_address_counter below.
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// d) response byte_cnt field. The response byte_cnt field contains a
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// decrementing sequence, such that each beat of the response contains the
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// count of bytes to follow. In the case of sub-bursts in a single packet,
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// the byte_cnt field may decrement down to num_symbols, then back up to
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// some value, multiple times in the packet.
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reg burst_uncompress_busy;
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reg [BYTE_CNT_W:0] burst_uncompress_byte_counter;
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wire [BYTE_CNT_W-1:0] burst_uncompress_byte_counter_lint;
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wire first_packet_beat;
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wire last_packet_beat;
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assign first_packet_beat = sink_valid & ~burst_uncompress_busy;
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assign burst_uncompress_byte_counter_lint = burst_uncompress_byte_counter[BYTE_CNT_W-1:0];
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// First cycle: burst_uncompress_byte_counter isn't ready yet, mux the input to
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// the output.
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assign source_byte_cnt =
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first_packet_beat ? sink_byte_cnt : burst_uncompress_byte_counter_lint;
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assign source_valid = sink_valid;
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// Last packet beat is set throughout receipt of an uncompressed read burst
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// from the response FIFO - this forces all the burst uncompression machinery
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// idle.
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assign last_packet_beat = ~sink_is_compressed |
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(
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burst_uncompress_busy ?
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(sink_valid & (burst_uncompress_byte_counter_lint == num_symbols)) :
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sink_valid & (sink_byte_cnt == num_symbols)
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);
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always @(posedge clk or posedge reset) begin
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if (reset) begin
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burst_uncompress_busy <= '0;
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burst_uncompress_byte_counter <= '0;
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end
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else begin
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if (source_valid & source_ready & sink_valid) begin
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// No matter what the current state, last_packet_beat leads to
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// idle.
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if (last_packet_beat) begin
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burst_uncompress_busy <= '0;
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burst_uncompress_byte_counter <= '0;
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end
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else begin
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if (burst_uncompress_busy) begin
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burst_uncompress_byte_counter <= (burst_uncompress_byte_counter > 0) ?
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(burst_uncompress_byte_counter_lint - num_symbols) :
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(sink_byte_cnt - num_symbols);
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end
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else begin // not busy, at least one more beat to go
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burst_uncompress_byte_counter <= sink_byte_cnt - num_symbols;
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// To do: should busy go true for numsymbols-size compressed
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// bursts?
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burst_uncompress_busy <= 1'b1;
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end
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end
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end
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end
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end
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reg [ADDR_W - 1 : 0 ] burst_uncompress_address_base;
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reg [ADDR_W - 1 : 0] burst_uncompress_address_offset;
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wire [63:0] decoded_burstsize_wire;
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wire [ADDR_W-1:0] decoded_burstsize;
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localparam ADD_BURSTWRAP_W = (ADDR_W > BURSTWRAP_W) ? ADDR_W : BURSTWRAP_W;
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wire [ADD_BURSTWRAP_W-1:0] addr_width_burstwrap;
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// The input burstwrap value can be used as a mask against address values,
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// but with one caveat: the address width may be (probably is) wider than
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// the burstwrap width. The spec says: extend the msb of the burstwrap
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// value out over the entire address width (but only if the address width
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// actually is wider than the burstwrap width; otherwise it's a 0-width or
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// negative range and concatenation multiplier).
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generate
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if (ADDR_W > BURSTWRAP_W) begin : addr_sign_extend
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// Sign-extend, just wires:
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assign addr_width_burstwrap[ADDR_W - 1 : BURSTWRAP_W] =
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{(ADDR_W - BURSTWRAP_W) {sink_burstwrap[BURSTWRAP_W - 1]}};
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assign addr_width_burstwrap[BURSTWRAP_W-1:0] = sink_burstwrap [BURSTWRAP_W-1:0];
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end
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else begin
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assign addr_width_burstwrap[BURSTWRAP_W-1 : 0] = sink_burstwrap;
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end
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endgenerate
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always @(posedge clk or posedge reset) begin
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if (reset) begin
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burst_uncompress_address_base <= '0;
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end
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else if (first_packet_beat & source_ready) begin
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burst_uncompress_address_base <= sink_addr & ~addr_width_burstwrap[ADDR_W-1:0];
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end
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end
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assign decoded_burstsize_wire = bytes_in_transfer(sink_burstsize); //expand it to 64 bits
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assign decoded_burstsize = decoded_burstsize_wire[ADDR_W-1:0]; //then take the width that is needed
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wire [ADDR_W : 0] p1_burst_uncompress_address_offset =
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(
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(first_packet_beat ?
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sink_addr :
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burst_uncompress_address_offset) + decoded_burstsize
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) &
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addr_width_burstwrap[ADDR_W-1:0];
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wire [ADDR_W-1:0] p1_burst_uncompress_address_offset_lint = p1_burst_uncompress_address_offset [ADDR_W-1:0];
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always @(posedge clk or posedge reset) begin
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if (reset) begin
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burst_uncompress_address_offset <= '0;
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end
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else begin
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if (source_ready & source_valid) begin
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burst_uncompress_address_offset <= p1_burst_uncompress_address_offset_lint;
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// if (first_packet_beat) begin
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// burst_uncompress_address_offset <=
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// (sink_addr + num_symbols) & addr_width_burstwrap;
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// end
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// else begin
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// burst_uncompress_address_offset <=
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// (burst_uncompress_address_offset + num_symbols) & addr_width_burstwrap;
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// end
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end
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end
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end
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// On the first packet beat, send the input address out unchanged,
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// while values are computed/registered for 2nd and subsequent beats.
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assign source_addr = first_packet_beat ? sink_addr :
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burst_uncompress_address_base | burst_uncompress_address_offset;
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assign source_burstwrap = sink_burstwrap;
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assign source_burstsize = sink_burstsize;
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//-------------------------------------------------------------------
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// A single (compressed) read burst will have sop/eop in the same beat.
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// A sequence of read sub-bursts emitted by a burst adapter in response to a
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// single read burst will have sop on the first sub-burst, eop on the last.
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// Assert eop only upon (sink_endofpacket & last_packet_beat) to preserve
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// packet conservation.
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assign source_startofpacket = sink_startofpacket & ~burst_uncompress_busy;
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assign source_endofpacket = sink_endofpacket & last_packet_beat;
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assign sink_ready = source_valid & source_ready & last_packet_beat;
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// This is correct for the slave agent usage, but won't always be true in the
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// width adapter. To do: add an "please uncompress" input, and use it to
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// pass-through or modify, and set source_is_compressed accordingly.
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assign source_is_compressed = 1'b0;
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endmodule
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