101 lines
2.2 KiB
Coq
101 lines
2.2 KiB
Coq
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/*
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* Milkymist SoC
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* Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012 Sebastien Bourdeauducq
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, version 3 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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module minimac3_tx(
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input phy_tx_clk,
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input tx_start,
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output reg tx_done,
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input [10:0] tx_count,
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input [7:0] txb_dat,
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output [10:0] txb_adr,
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output reg phy_tx_en,
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output reg [3:0] phy_tx_data
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);
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reg phy_tx_en_r;
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reg phy_tx_data_sel;
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wire [3:0] phy_tx_data_r = phy_tx_data_sel ? txb_dat[7:4] : txb_dat[3:0];
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always @(posedge phy_tx_clk) begin
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phy_tx_en <= phy_tx_en_r;
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phy_tx_data <= phy_tx_data_r;
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end
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reg [10:0] byte_count;
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reg byte_count_reset;
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reg byte_count_inc;
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always @(posedge phy_tx_clk) begin
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if(byte_count_reset)
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byte_count <= 11'd0;
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else if(byte_count_inc)
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byte_count <= byte_count + 11'd1;
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end
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assign txb_adr = byte_count;
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wire byte_count_max = byte_count == tx_count;
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parameter IDLE = 2'd0;
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parameter SEND_LO = 2'd1;
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parameter SEND_HI = 2'd2;
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parameter TERMINATE = 2'd3;
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reg [1:0] state;
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reg [1:0] next_state;
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initial state <= IDLE;
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always @(posedge phy_tx_clk)
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state <= next_state;
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always @(*) begin
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phy_tx_en_r = 1'b0;
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phy_tx_data_sel = 1'b0;
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byte_count_reset = 1'b0;
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byte_count_inc = 1'b0;
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tx_done = 1'b0;
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next_state = state;
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case(state)
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IDLE: begin
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byte_count_reset = 1'b1;
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if(tx_start)
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next_state = SEND_LO;
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end
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SEND_LO: begin
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byte_count_inc = 1'b1;
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phy_tx_en_r = 1'b1;
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phy_tx_data_sel = 1'b0;
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next_state = SEND_HI;
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end
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SEND_HI: begin
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phy_tx_en_r = 1'b1;
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phy_tx_data_sel = 1'b1;
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if(byte_count_max)
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next_state = TERMINATE;
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else
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next_state = SEND_LO;
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end
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TERMINATE: begin
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byte_count_reset = 1'b1;
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tx_done = 1'b1;
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next_state = IDLE;
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end
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endcase
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end
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endmodule
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