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    /xilinx_virtex_fp_library/trunk/SinglePathFPAdder
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Rev 8 → Rev 9

/SinglePathFPAdder.v
18,7 → 18,7
// Additional Comments:
//
//////////////////////////////////////////////////////////////////////////////////
module SinglePathFPAdder #( parameter size_mantissa = 24, //1.M
module SinglePathFPAdder #( parameter size_mantissa = 24, //calculate the size containing the hiden bit 1.M
parameter size_exponent = 8,
parameter size_exception_field = 2,
parameter size_counter = 5, //log2(size_mantissa) + 1 = 5)
32,36 → 32,40
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;
( 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_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_exception_field - 1 : 0] sp_case_a_number, sp_case_b_number;
wire [size_exponent : 0] a_greater_exponent, b_greater_exponent;
wire [size_exponent - 1 : 0] unadjusted_exponent;
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 [size_exponent : 0] exp_inter;
wire [size_mantissa - 1 : 0] shifted_m_b;
wire [size_mantissa - 1 : 0] initial_rounding_bits, inter_rounding_bits, final_rounding_bits;
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_counter - 1 : 0] lzs;
wire [size_mantissa + 1 : 0] adder_mantissa;
wire [size_mantissa + 1 : 0] rounded_mantissa;
wire [size_mantissa : 0] unnormalized_mantissa, unrounded_mantissa;
wire [size_mantissa-1: 0] resulted_mantissa;
wire [size_exponent-1: 0] resulted_exponent;
wire [size_exception_field - 1 : 0] resulted_exception_field;
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;
wire dummy_bit;
wire zero_flag;
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];
68,78 → 72,76
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 = (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
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]}};
//shift m_b_number
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))
.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));
.arith(1'b0),//logical shift
.shft(exp_difference),
.shifted_a({shifted_m_b, initial_rounding_bits}));
//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 adder_mantissa = (eff_op)? ({1'b0, m_a_number} - {1'b0, shifted_m_b}) : ({1'b0, m_a_number} + {1'b0, shifted_m_b});
//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;
assign {unnormalized_mantissa, inter_rounding_bits} =
(adder_mantissa[size_mantissa + 1])? ({~adder_mantissa[size_mantissa : 0], ~initial_rounding_bits}) :
({adder_mantissa[size_mantissa : 0], initial_rounding_bits});
//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),
leading_zeros #( .SIZE_INT(size_mantissa + 1), .SIZE_COUNTER(size_counter), .PIPELINE(pipeline))
leading_zeros_instance (.a(unnormalized_mantissa[size_mantissa : 0]),
.ovf(unnormalized_mantissa[size_mantissa]),
.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),
shifter #( .INPUT_SIZE(double_size_mantissa + 1),
.SHIFT_SIZE(size_counter),
.OUTPUT_SIZE(double_size_mantissa + 2),
.DIRECTION(1'b1), //0=right, 1=left
.PIPELINE(pipeline),
.POSITION(pipeline_pos))
shifter_instance( .a(unnormalized_mantissa),//mantissa
shifter_instance( .a({unnormalized_mantissa, inter_rounding_bits}),//mantissa
.arith(1'b0),//logical shift
.shft(lzs),
.shifted_a({unrounded_mantissa, dummy_bits}));
.shifted_a({unrounded_mantissa, final_rounding_bits, dummy_bit}));
//instantiate rounding_component
rounding #( .SIZE_MOST_S_MANTISSA(size_mantissa + 2),
.SIZE_LEAST_S_MANTISSA(size_mantissa))
rounding_instance( .unrounded_mantissa({1'b0, unrounded_mantissa}),
.dummy_bits(final_rounding_bits),
.rounded_mantissa(rounded_mantissa));
//
//assign g = dummy_bits[size_mantissa + 1];
//assign sticky = |(dummy_bits[size_mantissa : 0]);
//assign round_dec = g & (unrounded_mantissa[0] | sticky);
//adjust exponent in case of overflow
assign adjust_exponent = (rounded_mantissa[size_mantissa + 1])? 2'd2 : 2'd1;
//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);
assign unadjusted_exponent = exp_inter - lzs;
assign resulted_exponent = unadjusted_exponent + adjust_exponent;
//compute resulted_sign
assign resulted_sign = (eff_op)? ((shifted_m_a > shifted_m_b)? s_a_number : ~s_a_number) : s_a_number;
assign resulted_mantissa = (rounded_mantissa[size_mantissa + 1])? (rounded_mantissa[size_mantissa + 1 : 2]) : (rounded_mantissa[size_mantissa : 1]);
//compute exception_field
special_cases #( .size_exception_field(size_exception_field),
150,8 → 152,16
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]};
//set zero_flag in case of equal numbers
assign zero_flag = ~(|(resulted_mantissa));
//compute resulted_sign
assign resulted_sign = (eff_op)?
(!a_greater_exponent[size_exponent]? (!b_greater_exponent[size_exponent]? ~adder_mantissa[size_mantissa+1] : s_a_number) : ~s_b_number) :
s_a_number;
assign resulted_number_o = (zero_flag)? {size{1'b0}} :
{resulted_exception_field, resulted_sign, resulted_exponent, resulted_mantissa[size_mantissa - 2 : 0]};
endmodule

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