Subversion Repositories xilinx_virtex_fp_library

`timescale 1ns / 1ps

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

// Company: 

// Engineer: 

// 

// Create Date:    16:09:49 11/04/2013 

// Design Name: 

// Module Name:    SinglePathFPAdder 

// Project Name: 

// Target Devices: 

// Tool versions: 

// Description: A ± B

//

// Dependencies: 

//

// Revision: 

// Revision 0.01 - File Created

// Additional Comments: 

//

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

module SinglePathFPAdder #(     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 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)

                                                                        (sub, a_number_i, b_number_i, resulted_number_o);

        input sub;

        input [size - 1 : 0] a_number_i;

        input [size - 1 : 0] b_number_i;

        output[size - 1 : 0] resulted_number_o;

        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_exception_field - 1 : 0] sp_case_a_number, sp_case_b_number;

        wire [size_exponent - 1 : 0] exp_difference;

        wire [size_exponent - 1 : 0] modify_exp_a, modify_exp_b;

        wire [double_size_mantissa - 1 : 0] shifted_m_a, shifted_m_b;

        wire eff_op;

        wire [double_size_mantissa : 0] unnormalized_mantissa;

        wire [double_size_counter-1: 0] lzs;

        wire [size_mantissa-1: 0] unrounded_mantissa;

        wire [size_mantissa-1: 0] resulted_mantissa;

        wire [size_exponent-1: 0] resulted_exponent;

        wire resulted_sign;

        wire [size_exception_field - 1 : 0] resulted_exception_field;

        wire [size_mantissa + 1 : 0] dummy_bits;

        assign m_a_number = {1'b1, a_number_i[size_mantissa - 2 :0]};

        assign m_b_number       = {1'b1, b_number_i[size_mantissa - 2 :0]};

        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 difference between exponents

        assign exp_difference = (e_a_number > e_b_number)? (e_a_number - e_b_number) : (e_b_number - e_a_number);

        assign {modify_exp_a, modify_exp_b} = (e_a_number > e_b_number)? {8'd0, exp_difference} : {exp_difference, 8'd0};

        //shift the right mantissa

        shifter #(      .INPUT_SIZE(size_mantissa),

                                        .SHIFT_SIZE(size_exponent),

                                        .OUTPUT_SIZE(double_size_mantissa),

                                        .DIRECTION(1'b0), //0=right, 1=left

                                        .PIPELINE(pipeline),

                                        .POSITION(pipeline_pos))

                m_a_shifter_instance(   .a(m_a_number),//mantissa

                                                                                .arith(1'b0),//logical shift

                                                                                .shft(modify_exp_a),

                                                                                .shifted_a(shifted_m_a));

        shifter #(      .INPUT_SIZE(size_mantissa),

                                        .SHIFT_SIZE(size_exponent),

                                        .OUTPUT_SIZE(double_size_mantissa),

                                        .DIRECTION(1'b0), //0=right, 1=left

                                        .PIPELINE(pipeline),

                                        .POSITION(pipeline_pos))

                m_b_shifter_instance(   .a(m_b_number),//mantissa

                                                                                .arith(1'b0),//logical shift

                                                                                .shft(modify_exp_b),

                                                                                .shifted_a(shifted_m_b));

        //istantiate effective_operation_component

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

        //compute unnormalized_mantissa

        assign unnormalized_mantissa = (eff_op)? ((shifted_m_a > shifted_m_b)? (shifted_m_a - shifted_m_b) : (shifted_m_b - shifted_m_a)) :

                                                                                                                        shifted_m_a + shifted_m_b;

        //compute leading_zeros over unnormalized mantissa

        leading_zeros #(        .SIZE_INT(double_size_mantissa + 1'b1), .SIZE_COUNTER(double_size_counter), .PIPELINE(pipeline))

                leading_zeros_instance (.a(unnormalized_mantissa),

                                                                                .ovf(1'b0),

                                                                                .lz(lzs));

        //compute shifting over unnormalized_mantissa

        shifter #(      .INPUT_SIZE(double_size_mantissa + 1'b1),

                                        .SHIFT_SIZE(double_size_counter),

                                        .OUTPUT_SIZE(double_size_mantissa + 2'd2),

                                        .DIRECTION(1'b1), //0=right, 1=left

                                        .PIPELINE(pipeline),

                                        .POSITION(pipeline_pos))

                shifter_instance(       .a(unnormalized_mantissa),//mantissa

                                                                .arith(1'b0),//logical shift

                                                                .shft(lzs),

                                                                .shifted_a({unrounded_mantissa, dummy_bits}));

        //

        //assign g = dummy_bits[size_mantissa + 1];

        //assign sticky = |(dummy_bits[size_mantissa : 0]);

        //assign round_dec = g & (unrounded_mantissa[0] | sticky);

        //instantiate rounding_component

        rounding #(     .SIZE_MOST_S_MANTISSA(size_mantissa),

                                .SIZE_LEAST_S_MANTISSA(size_mantissa + 2'd2))

                rounding_instance(      .unrounded_mantissa(unrounded_mantissa),

                                    .dummy_bits(dummy_bits),

                                    .rounded_mantissa(resulted_mantissa));

        //compute resulted_exponent

        assign resulted_exponent = (e_a_number >= e_b_number)? (e_a_number - lzs + 1'b1) : (e_b_number - lzs + 1'b1);

        //compute resulted_sign

        assign resulted_sign = (eff_op)? ((shifted_m_a > shifted_m_b)? s_a_number : ~s_a_number) : s_a_number;

        //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));

        //generate final result                                                 

        assign resulted_number_o = {resulted_exception_field, resulted_sign, resulted_exponent, resulted_mantissa[size_mantissa-2 : 0]};

endmodule