Subversion Repositories xilinx_virtex_fp_library

`timescale 1ns / 1ps

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

// Company:     UPT

// Engineer:    Constantina-Elena Gavriliu

// 

// Create Date:    00:31:28 11/19/2013 

// Design Name: 

// Module Name:    DualPathFPAdder 

// Project Name: 

// Target Devices: 

// Tool versions: 

// Description: A ± B

//                              //do not take into consideration cases for which the operation generates a NaN or Infinity exception (with corresponding sign) when initial "special cases" are not such exceptions

//

// Dependencies:        ClosePath.v

//                                      FarPath.v

//                                      special_cases.v

//                                      effective_op.v

//

// Revision: 

// Revision 0.01 - File Created

// Additional Comments: 

//

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

module DualPathFPAdder #(       parameter size_mantissa                         = 24, //1.M

                                                        parameter size_exponent                         = 8,

                                                        parameter size_exception_field          = 2,

                                                        parameter size_counter                          = 5,    //log2(size_mantissa) + 1 = 5)

                                                        parameter [size_exception_field - 1 : 0] zero                    = 0, //00

                                                        parameter [size_exception_field - 1 : 0] normal_number   = 1, //01

                                                        parameter [size_exception_field - 1 : 0] infinity                = 2, //10

                                                        parameter [size_exception_field - 1 : 0] NaN                     = 3, //11

                                                        parameter [1 : 0] FP_operation   = 0,

                                                        parameter [1 : 0] FP_to_int              = 1,

                                                        parameter [1 : 0] int_operation = 3,

                                                        parameter pipeline                                      = 0,

                                                        parameter pipeline_pos                          = 0,     // 8 bits

                                                        parameter double_size_mantissa  = size_mantissa + size_mantissa,

                                                        parameter double_size_counter           = size_counter + 1,

                                                        parameter size  = size_mantissa + size_exponent + size_exception_field)

                                                        (       input [size - 1 : 0] a_number_i,

                                                                input [size - 1 : 0] b_number_i,

                                                                input sub,

                                                                output[size - 1 : 0] resulted_number_o);

        wire [size_exception_field - 1 : 0] sp_case_a_number, sp_case_b_number;

        wire [size_mantissa - 1 : 0] m_a_number, m_b_number;

        wire [size_exponent - 1 : 0] e_a_number, e_b_number;

        wire s_a_number, s_b_number;

        wire [size_exponent     : 0] a_greater_exponent, b_greater_exponent;

        wire [size_exponent - 1 : 0] exp_difference;

        wire [size_exponent     : 0] exp_inter;

        wire [size_mantissa - 1 : 0] shifted_m_b;

        wire [size_mantissa - 1 : 0] initial_rounding_bits, inter_rounding_bits;

        wire eff_op;

        wire [size_mantissa     : 0] unnormalized_mantissa;

        wire [size_mantissa-1 : 0] fp_resulted_m_o, cp_resulted_m_o;

        wire [size_exponent-1 : 0] fp_resulted_e_o, cp_resulted_e_o;

        wire [size_exception_field - 1 : 0] resulted_exception_field;

        wire resulted_sign;

        wire zero_flag;

        wire [4:0] sign_cases;

        reg intermediar_sign;

        assign e_a_number       = a_number_i[size_mantissa + size_exponent - 1 : size_mantissa - 1];

        assign e_b_number = b_number_i[size_mantissa + size_exponent - 1 : size_mantissa - 1];

        assign s_a_number = a_number_i[size - size_exception_field - 1];

        assign s_b_number = b_number_i[size - size_exception_field - 1];

        assign sp_case_a_number = a_number_i[size - 1 : size - size_exception_field];

        assign sp_case_b_number = b_number_i[size - 1 : size - size_exception_field];

        //find the greater exponent

        assign a_greater_exponent = e_a_number - e_b_number;

        assign b_greater_exponent = e_b_number - e_a_number;

        //find the difference between exponents

        assign exp_difference   = (a_greater_exponent[size_exponent])? b_greater_exponent[size_exponent - 1 : 0] : a_greater_exponent[size_exponent - 1 : 0];

        assign exp_inter                = (b_greater_exponent[size_exponent])? {1'b0, e_a_number} : {1'b0, e_b_number};

        //set shifter always on m_b_number

        assign {m_a_number, m_b_number} = (b_greater_exponent[size_exponent])?

                                                                                                        {{1'b1, a_number_i[size_mantissa - 2 :0]}, {1'b1, b_number_i[size_mantissa - 2 :0]}} :

                                                                                                        {{1'b1, b_number_i[size_mantissa - 2 :0]}, {1'b1, a_number_i[size_mantissa - 2 :0]}};

        effective_op effective_op_instance( .a_sign(s_a_number), .b_sign(s_b_number), .sub(sub), .eff_op(eff_op));

        //instantiate FarPath component

        FarPath #(      .size_in_mantissa(size_mantissa),

                                        .size_out_mantissa(size_mantissa),

                                        .size_exponent(size_exponent),

                                        .pipeline(pipeline),

                                        .pipeline_pos(pipeline_pos),

                                        .size_counter(size_counter),

                                        .double_size_in_mantissa(double_size_mantissa))

                FarPath_instance (      .m_a_number(m_a_number),

                                                        .m_b_number(m_b_number),

                                                        .eff_op(eff_op),

                                                        .exp_difference(exp_difference),

                                    .exp_inter(exp_inter),

                                    .resulted_m_o(fp_resulted_m_o),

                                    .resulted_e_o(fp_resulted_e_o));

        //instantiate ClosePath component

        ClosePath #(.size_in_mantissa(size_mantissa),

                                        .size_out_mantissa(size_mantissa),

                                        .size_exponent(size_exponent),

                                        .pipeline(pipeline),

                                        .pipeline_pos(pipeline_pos),

                                        .size_counter(size_counter),

                                        .double_size_in_mantissa(double_size_mantissa))

                ClosePath_instance(     .m_a_number(m_a_number),

                                                        .m_b_number(m_b_number),

                                                        .exp_difference(exp_difference[0]),

                                                                .exp_inter(exp_inter),

                                                                .resulted_m_o(cp_resulted_m_o),

                                                                .resulted_e_o(cp_resulted_e_o),

                                                                .ovf(ovf));

        //compute exception_field

        special_cases   #(      .size_exception_field(size_exception_field),

                                                        .zero(zero),

                                                        .normal_number(normal_number),

                                                        .infinity(infinity),

                                                        .NaN(NaN))

                special_cases_instance( .sp_case_a_number(sp_case_a_number),

                                                                                .sp_case_b_number(sp_case_b_number),

                                                                                .sp_case_result_o(resulted_exception_field));

        //set zero_flag in case of equal numbers

        assign zero_flag = (exp_difference > 1 | !eff_op)?

                                                                ~((|{fp_resulted_m_o, resulted_exception_field[1]}) & (|resulted_exception_field))  :

                                                                ~((|{cp_resulted_m_o, resulted_exception_field[1]}) & (|resulted_exception_field));

        assign sign_cases = {eff_op, s_a_number, s_b_number, a_greater_exponent[size_exponent], b_greater_exponent[size_exponent]};

        always

                @(*)

        begin

                case (sign_cases)

                        5'b00000:       intermediar_sign = 1'b0;

                        5'b00001:       intermediar_sign = 1'b0;

                        5'b00010:       intermediar_sign = 1'b0;

                        5'b10000:       intermediar_sign = ~ovf;

                        5'b10001:       intermediar_sign = 1'b0;

                        5'b10010:       intermediar_sign = 1'b1;

                        5'b10100:       intermediar_sign = ~ovf;

                        5'b10101:       intermediar_sign = 1'b0;

                        5'b10110:       intermediar_sign = 1'b1;

                        5'b00100:       intermediar_sign = 1'b0;

                        5'b00101:       intermediar_sign = 1'b0;

                        5'b00110:       intermediar_sign = 1'b0;

                        5'b11000:       intermediar_sign = ovf;

                        5'b11001:       intermediar_sign = 1'b1;

                        5'b11010:       intermediar_sign = 1'b0;

                        5'b01000:       intermediar_sign = 1'b1;

                        5'b01001:       intermediar_sign = 1'b1;

                        5'b01010:       intermediar_sign = 1'b1;

                        5'b01100:       intermediar_sign = 1'b1;

                        5'b01101:       intermediar_sign = 1'b1;

                        5'b01110:       intermediar_sign = 1'b1;

                        5'b11100:       intermediar_sign = ovf;

                        5'b11101:       intermediar_sign = 1'b1;

                        5'b11110:       intermediar_sign = 1'b0;

                        default: intermediar_sign = 1'b1;

                endcase

        end

        assign resulted_sign = intermediar_sign;

        assign resulted_number_o = (zero_flag)? {size{1'b0}} :

                                                                        (!sp_case_a_number)? {b_number_i[size-1 : size-size_exception_field], eff_op ^ s_b_number, b_number_i[size-1-size_exception_field-1 : 0]} :

                                                                        (!sp_case_b_number)? {a_number_i[size-1 : 0]} :

                                                                        (exp_difference > 1 | !eff_op)?         {resulted_exception_field, resulted_sign, fp_resulted_e_o, fp_resulted_m_o[size_mantissa-2 : 0]}:

                                                                                                                                                {resulted_exception_field, resulted_sign, cp_resulted_e_o, cp_resulted_m_o[size_mantissa-2 : 0]};

endmodule