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[/] [aor3000/] [trunk/] [sim/] [div-test/] [main.v] - Blame information for rev 2

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1 2 alfik
/*
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 * This file is subject to the terms and conditions of the BSD License. See
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 * the file "LICENSE" in the main directory of this archive for more details.
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 *
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 * Copyright (C) 2014 Aleksander Osman
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 */
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module main(
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    input               clk,
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    input               rst_n,
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    input               start,
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    input       [2:0]  dividend,
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    input       [2:0]  divisor,
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    output              ready,
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    output      [1:0]  quotient,
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    output      [1:0]  remainder
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);
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//------------------------------------------------------------------------------
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reg [5:0] div_counter;
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always @(posedge clk or negedge rst_n) begin
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    if(rst_n == 1'b0)               div_counter <= 6'd0;
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    else if(start)                  div_counter <= 6'd3;
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    else if(div_counter != 6'd0)    div_counter <= div_counter - 6'd1;
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end
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wire div_working = div_counter > 6'd1;
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wire [4:0] div_diff = { 2'd0, div_dividend } - div_divisor;
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reg [1:0] div_dividend;
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always @(posedge clk or negedge rst_n) begin
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    if(rst_n == 1'b0)                               div_dividend <= 2'd0;
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    else if(start && dividend[2] == 1'b0)          div_dividend <=  dividend[1:0];
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    else if(start && dividend[2] == 1'b1)          div_dividend <= -dividend[1:0];
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    else if(div_working && div_diff[4] == 1'b0)    div_dividend <= div_diff[1:0];
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end
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wire [2:0] divisor_neg = -divisor;
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reg [3:0] div_divisor;
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always @(posedge clk or negedge rst_n) begin
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    if(rst_n == 1'b0)                               div_divisor <= 4'd0;
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    else if(start && divisor[2] == 1'b0)           div_divisor <= { 1'b0, divisor[1:0],     1'd0 };
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    else if(start && divisor[2] == 1'b1)           div_divisor <= { 1'b0, divisor_neg[1:0], 1'd0 };
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    else if(div_working)                            div_divisor <= { 1'b0, div_divisor[3:1] };
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end
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reg [1:0] div_quotient;
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always @(posedge clk or negedge rst_n) begin
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    if(rst_n == 1'b0)                               div_quotient <= 2'd0;
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    else if(start)                                  div_quotient <= 2'd0;
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    else if(div_working && div_diff[4] == 1'b0)    div_quotient <= { div_quotient[0], 1'b1 };
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    else if(div_working && div_diff[4] == 1'b1)    div_quotient <= { div_quotient[0], 1'b0 };
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end
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reg div_quotient_neg;
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always @(posedge clk or negedge rst_n) begin
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    if(rst_n == 1'b0)   div_quotient_neg <= 1'b0;
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    else if(start)      div_quotient_neg <= dividend[2] ^ divisor[2];
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end
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reg div_remainder_neg;
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always @(posedge clk or negedge rst_n) begin
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    if(rst_n == 1'b0)   div_remainder_neg <= 1'b0;
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    else if(start)      div_remainder_neg <= dividend[2];
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end
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assign ready     = div_counter == 6'd1;
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assign quotient  = (div_quotient_neg)?   -div_quotient[1:0] : div_quotient[1:0];
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assign remainder = (div_remainder_neg)?  -div_dividend[1:0] : div_dividend[1:0];
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//------------------------------------------------------------------------------
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wire _unused_ok = &{ 1'b0, div_diff[3:2], divisor_neg[2],  1'b0 };
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//------------------------------------------------------------------------------
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endmodule

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