Subversion Repositories xilinx_virtex_fp_library

`timescale 1ns / 1ps

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

// Company:     UPT

// Engineer:    Constantina-Elena Gavriliu

// 

// Create Date:    00:31:57 11/19/2013 

// Design Name: 

// Module Name:    FarPath 

// Project Name: 

// Target Devices: 

// Tool versions: 

// Description: A ± B when |Ea-Eb| >= 2

//

// Dependencies:        rounding.v

//                                      shifter.v

//

// Revision: 

// Revision 0.01 - File Created

// Additional Comments: 

//

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module FarPath  #(      parameter size_in_mantissa                      = 24,   //1.M

                                        parameter size_out_mantissa                     = 24,

                                        parameter size_exponent                         = 8,

                                        parameter pipeline                                      = 0,

                                        parameter pipeline_pos                          = 0,     // 8 bits

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

                                        parameter double_size_in_mantissa   = size_in_mantissa + size_in_mantissa)

                                (       input [size_in_mantissa - 1     : 0] m_a_number,

                                        input [size_in_mantissa - 1 : 0] m_b_number,

                                        input eff_op,

                                        input [size_exponent            : 0] exp_inter,

                                        input [size_exponent - 1 : 0] exp_difference,

                                        output[size_out_mantissa- 1 : 0] resulted_m_o,

                                        output[size_exponent - 1        : 0] resulted_e_o);

        wire [size_exponent - 1 : 0] adjust_mantissa;

        wire [size_exponent - 1 : 0] unadjusted_exponent;

        wire [double_size_in_mantissa:0] normalized_mantissa;

        wire [size_in_mantissa - 1      : 0] shifted_m_b;

        wire [size_in_mantissa + 2      : 0] adder_mantissa;

        wire [size_in_mantissa + 1      : 0] unnormalized_mantissa;

        wire [size_in_mantissa - 1 : 0] initial_rounding_bits;

        wire [size_in_mantissa - 2 : 0] inter_rounding_bits;

        wire dummy_bit;

        wire dummy_ovf, negation_cond, correction;

        //shift m_b_number                              

        shifter #(      .INPUT_SIZE(size_in_mantissa),

                                .SHIFT_SIZE(size_exponent),

                                .OUTPUT_SIZE(double_size_in_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(exp_difference),

                                                                .shifted_a({shifted_m_b, initial_rounding_bits}));

        //compute addition

        assign adder_mantissa = (eff_op)?       ({1'b0, m_a_number, 1'b0} - {1'b0, shifted_m_b, initial_rounding_bits[size_in_mantissa - 1]}) :

                                                                                ({1'b0, m_a_number, 1'b0} + {1'b0, shifted_m_b, initial_rounding_bits[size_in_mantissa - 1]});

        //compute unnormalized_mantissa

        assign unnormalized_mantissa = (adder_mantissa[size_in_mantissa + 2])? ~adder_mantissa[size_in_mantissa + 1 : 0] : adder_mantissa[size_in_mantissa + 1 : 0];

        assign inter_rounding_bits = ((eff_op)? ((|initial_rounding_bits[size_in_mantissa - 2 : 0])?~initial_rounding_bits[size_in_mantissa - 2 : 0] : initial_rounding_bits[size_in_mantissa - 2 : 0]) : initial_rounding_bits[size_in_mantissa - 2 : 0]);

        assign adjust_mantissa = unnormalized_mantissa[size_in_mantissa + 1]? 2'd0 :

                                                                                unnormalized_mantissa[size_in_mantissa]? 2'd1 : 2'd2;

        //compute shifting over unnormalized_mantissa

        shifter #(      .INPUT_SIZE(double_size_in_mantissa+1),

                                        .SHIFT_SIZE(size_exponent),

                                        .OUTPUT_SIZE(double_size_in_mantissa+2),

                                        .DIRECTION(1'b1),

                                        .PIPELINE(pipeline),

                                        .POSITION(pipeline_pos))

                unnormalized_no_shifter_instance(.a({unnormalized_mantissa, inter_rounding_bits}),

                                                                                                        .arith(inter_rounding_bits[0]),

                                                                                                        .shft(adjust_mantissa),

                                                                                                        .shifted_a({normalized_mantissa, dummy_bit}));

        assign correction = eff_op? ((|initial_rounding_bits[size_in_mantissa - 2 : 0])?

                                                                ((adder_mantissa[0] | ((~adder_mantissa[0]) & (~adder_mantissa[size_in_mantissa]) & (~initial_rounding_bits[size_in_mantissa - 1])

                                                                                & (~(&{normalized_mantissa[size_in_mantissa-1 : 0],dummy_bit}))))? 1'b1 : 1'b0) : 1'b0) : 1'b0;

        //instantiate rounding_component

        rounding #(     .SIZE_MOST_S_MANTISSA(size_out_mantissa),

                                        .SIZE_LEAST_S_MANTISSA(size_out_mantissa + 2'd1))

                rounding_instance(      .unrounded_mantissa(normalized_mantissa[double_size_in_mantissa : double_size_in_mantissa - size_out_mantissa + 1]),

                                                                        .dummy_bits(normalized_mantissa[double_size_in_mantissa - size_out_mantissa: 0]),

                                                                        .correction(correction),

                                                                        .rounded_mantissa(resulted_m_o));

        assign unadjusted_exponent = exp_inter - adjust_mantissa;

        assign resulted_e_o = unadjusted_exponent + 1'b1;

endmodule