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//////////////////////////////////////////////////////////////////////

////                                                              ////

////  or1200_fpu_div                                              ////

////                                                              ////

////  This file is part of the OpenRISC 1200 project              ////

////  http://opencores.org/project,or1k                           ////

////                                                              ////

////  Description                                                 ////

////  division entity for the division unit                       ////

////                                                              ////

////  To Do:                                                      ////

////                                                              ////

////                                                              ////

////  Author(s):                                                  ////

////      - Original design (FPU100) -                            ////

////        Jidan Al-eryani, jidan@gmx.net                        ////

////      - Conv. to Verilog and inclusion in OR1200 -            ////

////        Julius Baxter, julius@opencores.org                   ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

//

//  Copyright (C) 2006, 2010

//

//      This source file may be used and distributed without        

//      restriction provided that this copyright statement is not   

//      removed from the file and that any derivative work contains 

//      the original copyright notice and the associated disclaimer.

//                                                           

//              THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY     

//      EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED   

//      TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS   

//      FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR      

//      OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,         

//      INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES    

//      (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE   

//      GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR        

//      BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF  

//      LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT  

//      (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT  

//      OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE         

//      POSSIBILITY OF SUCH DAMAGE. 

//

module or1200_fpu_div

  (

   clk_i,

   dvdnd_i,

   dvsor_i,

   sign_dvd_i,

   sign_div_i,

   start_i,

   ready_o,

   qutnt_o,

   rmndr_o,

   sign_o,

   div_zero_o

   );

   parameter FP_WIDTH = 32;

   parameter MUL_SERIAL = 0; // 0 for parallel multiplier, 1 for serial

   parameter MUL_COUNT = 11; //11 for parallel multiplier, 34 for serial

   parameter FRAC_WIDTH = 23;

   parameter EXP_WIDTH = 8;

   parameter ZERO_VECTOR = 31'd0;

   parameter INF = 31'b1111111100000000000000000000000;

   parameter QNAN = 31'b1111111110000000000000000000000;

   parameter SNAN = 31'b1111111100000000000000000000001;

   input clk_i;

   input [2*(FRAC_WIDTH+2)-1:0] dvdnd_i;

   input [FRAC_WIDTH+3:0]        dvsor_i;

   input                        sign_dvd_i;

   input                        sign_div_i;

   input                        start_i;

   output                       ready_o;

   output [FRAC_WIDTH+3:0]       qutnt_o;

   output [FRAC_WIDTH+3:0]       rmndr_o;

   output                       sign_o;

   output                       div_zero_o;

   parameter t_state_waiting = 1'b0,

               t_state_busy = 1'b1;

   reg [FRAC_WIDTH+3:0]  s_qutnt_o;

   reg [FRAC_WIDTH+3:0]  s_rmndr_o;

   reg [2*(FRAC_WIDTH+2)-1:0]    s_dvdnd_i;

   reg [FRAC_WIDTH+3:0]  s_dvsor_i;

   reg                          s_sign_dvd_i, s_sign_div_i;

   wire                         s_sign_o;

   wire                         s_div_zero_o;

   reg                          s_start_i;

   reg                          s_ready_o;

   reg                          s_state;

   reg [4:0]                     s_count;

   reg [FRAC_WIDTH+3:0]  s_dvd;

   // Input Register

   always @(posedge clk_i)

     begin

        s_dvdnd_i <= dvdnd_i;

        s_dvsor_i <= dvsor_i;

        s_sign_dvd_i<= sign_dvd_i;

        s_sign_div_i<= sign_div_i;

        s_start_i <= start_i;

     end

   assign qutnt_o = s_qutnt_o;

   assign rmndr_o = s_rmndr_o;

   assign sign_o = s_sign_o;

   assign ready_o = s_ready_o;

   assign div_zero_o = s_div_zero_o;

   assign s_sign_o = sign_dvd_i ^ sign_div_i;

   assign s_div_zero_o = !(|s_dvsor_i) & (|s_dvdnd_i);

   always @(posedge clk_i)

     if (s_start_i)

       begin

          s_state <= t_state_busy;

          s_count <= 26;

       end

     else if (!(|s_count) & s_state==t_state_busy)

       begin

          s_state <= t_state_waiting;

          s_ready_o <= 1;

          s_count <=26;

       end

     else if (s_state==t_state_busy)

       s_count <= s_count - 1;

     else

       begin

          s_state <= t_state_waiting;

          s_ready_o <= 0;

       end

   wire [26:0] v_div;

   assign v_div = (s_count==26) ? {3'd0,s_dvdnd_i[49:26]} : s_dvd;

   wire [26:0] v_div_minus_s_dvsor_i;

   assign v_div_minus_s_dvsor_i = v_div - s_dvsor_i;

   always @(posedge clk_i)

     begin

        //Reset

        if (s_start_i)

          begin

             s_qutnt_o <= 0;

             s_rmndr_o <= 0;

          end

        else if (s_state==t_state_busy)

          begin

             if (v_div < s_dvsor_i)

               begin

                  s_qutnt_o[s_count] <= 1'b0;

                  s_dvd <= {v_div[25:0],1'b0};

               end

             else

               begin

                  s_qutnt_o[s_count] <= 1'b1;

                  s_dvd <= {v_div_minus_s_dvsor_i[25:0],1'b0};

               end

             s_rmndr_o <= v_div;

          end // if (s_state==t_state_busy)

     end // always @ (posedge clk_i)

endmodule // or1200_fpu_div