Commit 3a04a2c6 authored by Andrey Filippov's avatar Andrey Filippov

Imlemented single-clock bit stuffer to aggregate MSB aligned variable-length...

Imlemented single-clock bit stuffer to aggregate MSB aligned variable-length (1..27) data to 32-bit words
parent 034b2a33
/*******************************************************************************
* Module: bit_stuffer_27_32
* Date:2015-10-23
* Author: andrey
* Description: Aggregate MSB aligned variable-length (1..27) data to 32-bit words
*
* Copyright (c) 2015 Elphel, Inc .
* bit_stuffer_27_32.v is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* bit_stuffer_27_32.v is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/> .
*******************************************************************************/
`timescale 1ns/1ps
module bit_stuffer_27_32#(
parameter DIN_LEN = 27
)(
input xclk, // pixel clock, sync to incoming data
input rst, // @xclk
input [DIN_LEN-1:0] din, // input data, MSB aligned
input [4:0] dlen, // input data width
input ds, // input data valid
input flush_in, // flush remaining data
output [31:0] d_out, // outpt 32-bit data
output reg [2:0] bytes_out, // bytes left when flush?
output reg dv, // output data valid
output flush_out // delayed flush in matching the data latency
);
localparam DATA1_LEN = DIN_LEN + 32 - 8;
localparam DATA2_LEN = DIN_LEN + 32 - 2;
localparam DATA3_LEN = DIN_LEN + 32 - 1;
reg [DATA1_LEN-1:0] data1; // first stage of the barrel shifter
reg [DATA2_LEN-1:0] data2; // second stage of the barrel shifter
reg [DATA3_LEN-1:0] data3; // second stage of the barrel shifter/ output register
// reg dv_r;
// assign dv = dv_r;
reg [5:0] early_length; // number of bits in the last word (mod 32)
reg [5:0] dlen1; // use for the stage 2, MSB - carry out
reg [5:0] dlen2; // use for the satge 3
reg [31:0] dmask2_rom; // data mask (sync with data2) - 1 use new data, 0 - use old data. Use small ROM?
reg [2:0] stage; // enable shifter stage
wire [5:0] pre_bits_out_w = dlen2[4:0] + 5'h7;
assign d_out = data3[DATA3_LEN-1 -: 32];
always @ (posedge xclk) begin
if (rst) bytes_out <= 0;
else if (stage[1]) bytes_out <= pre_bits_out_w[5:3];
if (rst) stage <= 0;
else stage <= {stage[1:0], ds};
if (rst) early_length <= 0;
else if (ds) early_length <= early_length[4:0] + dlen; // early_length[5] is not used in calculations, it is just carry out
if (rst) dlen1 <= 0;
else if (ds) dlen1 <= early_length; // previous value
if (rst) dlen2 <= 0;
else if (stage[0]) dlen2 <= dlen1; // previous value (position)
// barrel shifter stage 1 (0/8/16/24)
if (ds) case (early_length[4:3])
2'h0: data1 <= { din, 24'b0};
2'h1: data1 <= { 8'b0,din, 16'b0};
2'h2: data1 <= {16'b0,din, 8'b0};
2'h3: data1 <= {24'b0,din };
endcase
// barrel shifter stage 2 (0/2/4/6)
if (stage[0]) case (dlen1[2:1])
2'h0: data2 <= { data1, 6'b0};
2'h1: data2 <= { 2'b0,data1, 4'b0};
2'h2: data2 <= { 4'b0,data1, 2'b0};
2'h3: data2 <= { 6'b0,data1 };
endcase
if (stage[0]) case (dlen1[4:0])
5'h00: dmask2_rom <= 32'hffffffff;
5'h01: dmask2_rom <= 32'hfffffffe;
5'h02: dmask2_rom <= 32'hfffffffc;
5'h03: dmask2_rom <= 32'hfffffff8;
5'h04: dmask2_rom <= 32'hfffffff0;
5'h05: dmask2_rom <= 32'hffffffe0;
5'h06: dmask2_rom <= 32'hffffffc0;
5'h07: dmask2_rom <= 32'hffffff80;
5'h08: dmask2_rom <= 32'hffffff00;
5'h09: dmask2_rom <= 32'hfffffe00;
5'h0a: dmask2_rom <= 32'hfffffc00;
5'h0b: dmask2_rom <= 32'hfffff800;
5'h0c: dmask2_rom <= 32'hfffff000;
5'h0d: dmask2_rom <= 32'hffffe000;
5'h0e: dmask2_rom <= 32'hffffc000;
5'h0f: dmask2_rom <= 32'hffff8000;
5'h10: dmask2_rom <= 32'hffff0000;
5'h11: dmask2_rom <= 32'hfffe0000;
5'h12: dmask2_rom <= 32'hfffc0000;
5'h13: dmask2_rom <= 32'hfff80000;
5'h14: dmask2_rom <= 32'hfff00000;
5'h15: dmask2_rom <= 32'hffe00000;
5'h16: dmask2_rom <= 32'hffc00000;
5'h17: dmask2_rom <= 32'hff800000;
5'h18: dmask2_rom <= 32'hff000000;
5'h19: dmask2_rom <= 32'hfe000000;
5'h1a: dmask2_rom <= 32'hfc000000;
5'h1b: dmask2_rom <= 32'hf8000000;
5'h1c: dmask2_rom <= 32'hf0000000;
5'h1d: dmask2_rom <= 32'he0000000;
5'h1e: dmask2_rom <= 32'hc0000000;
5'h1f: dmask2_rom <= 32'h80000000;
endcase
// barrel shifter stage 3 (0/1), combined with output/hold register
if (stage[1]) begin
data3[DATA3_LEN-1 -: 32] <= (~dmask2_rom & (dlen2[5] ? {data3[DATA3_LEN-1-32 : 0],6'b0}: data3[DATA3_LEN-1 -: 32])) |
( dmask2_rom & (dlen2[0] ? {1'b0,data2[DATA2_LEN-1 -: 31]} : data2[DATA2_LEN-1 -: 32]));
data3[DATA3_LEN-1-32: 0] <= dlen2[0] ? data2[DATA2_LEN-31-1 : 0] : {data2[DATA2_LEN-32-1 : 0], 1'b0};
end
dv <= stage[1] && dlen2[5];
end
endmodule
......@@ -224,7 +224,7 @@ module cmd_encod_tiled_32_rd #(
// ROM-based (registered output) encoded sequence
always @ (posedge clk) begin
if (mrst) rom_r <= 0;
if (mrst) rom_r <= 0; // TODO: make mrst cause gen_addr = 4'hf?
else case (gen_addr)
4'h0: rom_r <= (ENC_CMD_ACTIVATE << ENC_CMD_SHIFT) | (1 << ENC_NOP) | (1 << ENC_PAUSE_SHIFT); // here does not matter, just to work with masked ACTIVATE
4'h1: rom_r <= (ENC_CMD_ACTIVATE << ENC_CMD_SHIFT);
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment