float_built_bus26.v

IEEE754 floating point adder

/* ------------------------------------------------------------
// MODULE: Float_Built_Bus26 (no clock)
// Edition: one
// Matlab Code:  None
// C Code: None
// Architecture Diagram: add_sub_floating.ppt
// Date: 2008/01/30
// Update: 2008/01/30
//         2008/02/12 debug for zero
// ------------------------------------------------------------ */
module Float_Built_Bus26(data_sgnfc_in,data_exp_in,data_out);

/* ------------------------------------------------------------
// Parameters definition
// ------------------------------------------------------------ */

/* ------------------------------------------------------------
// Unmodified arameters definition
// ------------------------------------------------------------ */

parameter in_sgnfc_lng=26,//data_in significant part length
	  out_sgnfc_lng=25,//data_out significant part length
	  exp_lng=7,//data_in(out) exponent part length
	  out_data_lng=32;//data_out total length
	  
/* ------------------------------------------------------------
// I/O declaration
// ------------------------------------------------------------ */
input [in_sgnfc_lng-1:0]data_sgnfc_in; //data_sgnfc_in

input [exp_lng-1:0]data_exp_in; //data_exp_in

output [out_data_lng-1:0]data_out; //  data_out

/* ------------------------------------------------------------
// Connection wire declaration
// ------------------------------------------------------------ */
wire [in_sgnfc_lng-2:0]compl_data_sgnfc; //inv data_sgnfc_in

wire [in_sgnfc_lng-2:0]decoder_in; //input for decoder

reg [5:0]exp_shift_number; //shifter number for exp //must modified by hand

reg [4:0]shift_number; //shifter number for exp //must modified by hand

wire [in_sgnfc_lng-2:0]shifted_data;

wire [exp_lng:0]exp_out;
wire [out_sgnfc_lng-1:0]sgnfc_out;
wire min_overflow;//only detect too small value for debug in total system

wire [exp_lng-1:0] exp_out_real;

/* ------------------------------------------------------------
// Module instance
// ------------------------------------------------------------ */

//assign compl_data_sgnfc=~data_sgnfc_in[in_sgnfc_lng-2:0];
assign decoder_in=data_sgnfc_in[in_sgnfc_lng-2:0];

//decoder for shift number

always @(decoder_in)
begin
	if (decoder_in[in_sgnfc_lng-2])//copy until "in_sgnfc_lng-X=0"
	begin
		exp_shift_number<=6'b00_0001;//in_sgnfc_lng-out_sgnfc_lng=1//change here
		shift_number<=5'd0;//dont touch
	end
	else
	if (decoder_in[in_sgnfc_lng-3])
	begin
		exp_shift_number<=6'b00_0000;//0//change here
		shift_number<=5'd1;//dont touch
	end
	else
	if (decoder_in[in_sgnfc_lng-4])
	begin
		exp_shift_number<=6'b11_1111;//-1//change here
		shift_number<=5'd2;//dont touch
	end
	else
	if (decoder_in[in_sgnfc_lng-5])
	begin
		exp_shift_number<=6'b11_1110;//-2//change here
		shift_number<=5'd3;//dont touch
	end
	else
	if (decoder_in[in_sgnfc_lng-6])
	begin
		exp_shift_number<=6'b11_1101;//-3//change here
		shift_number<=5'd4;//dont touch
	end
	else
	if (decoder_in[in_sgnfc_lng-7])
	begin
		exp_shift_number<=6'b11_1100;//-4//change here
		shift_number<=5'd5;//dont touch
	end
	else
	if (decoder_in[in_sgnfc_lng-8])
	begin
		exp_shift_number<=6'b11_1011;//-5//change here
		shift_number<=5'd6;//dont touch
	end
	else
	if (decoder_in[in_sgnfc_lng-9])
	begin
		exp_shift_number<=6'b11_1010;//-6//change here
		shift_number<=5'd7;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-10])
	begin
		exp_shift_number<=6'b11_1001;//-7//change here
		shift_number<=5'd8;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-11])
	begin
		exp_shift_number<=6'b11_1000;//-8//change here
		shift_number<=5'd9;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-12])
	begin
		exp_shift_number<=6'b11_0111;//-9//change here
		shift_number<=5'd10;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-13])
	begin
		exp_shift_number<=6'b11_0110;//-10//change here
		shift_number<=5'd11;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-14])
	begin
		exp_shift_number<=6'b11_0101;//-11//change here
		shift_number<=5'd12;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-15])
	begin
		exp_shift_number<=6'b11_0100;//-12//change here
		shift_number<=5'd13;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-16])
	begin
		exp_shift_number<=6'b11_0011;//-13//change here
		shift_number<=5'd14;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-17])
	begin
		exp_shift_number<=6'b11_0010;//-14//change here
		shift_number<=5'd15;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-18])
	begin
		exp_shift_number<=6'b11_0001;//-15//change here
		shift_number<=5'd16;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-19])
	begin
		exp_shift_number<=6'b11_0000;//-16//change here
		shift_number<=5'd17;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-20])
	begin
		exp_shift_number<=6'b10_1111;//-17//change here
		shift_number<=5'd18;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-21])
	begin
		exp_shift_number<=6'b10_1110;//-18//change here
		shift_number<=5'd19;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-22])
	begin
		exp_shift_number<=6'b10_1101;//-19//change here
		shift_number<=5'd20;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-23])
	begin
		exp_shift_number<=6'b10_1100;//-20//change here
		shift_number<=5'd21;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-24])
	begin
		exp_shift_number<=6'b10_1011;//-21//change here
		shift_number<=5'd22;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-25])
	begin
		exp_shift_number<=6'b10_1010;//-22//change here
		shift_number<=5'd23;//dont touch
	end
	else 
	if (decoder_in[in_sgnfc_lng-26])
	begin
		exp_shift_number<=6'b10_1001;//-23//change here
		shift_number<=5'd24;//dont touch
	end
	else //mean this number is zero
	begin
		exp_shift_number<=6'b0;//0//dont touch
		shift_number<=in_sgnfc_lng;//dont touch
	end		

end

//exp 

assign exp_out={{2{exp_shift_number[5]}},exp_shift_number}+{data_exp_in[6],data_exp_in};

assign min_overflow=(exp_out[exp_lng]&~exp_out[exp_lng-1]); //1:0 for min overfloe//0:1 for max overflow//XOR for min and max overflow

//shift

assign shifted_data=data_sgnfc_in[in_sgnfc_lng-2:0]<<shift_number;
assign sgnfc_out=min_overflow?{out_sgnfc_lng{1'b0}}:{data_sgnfc_in[in_sgnfc_lng-1],shifted_data[in_sgnfc_lng-2:in_sgnfc_lng-out_sgnfc_lng]};

//output results

assign exp_out_real = ((min_overflow)||(~sgnfc_out[out_sgnfc_lng-2])) ? 7'b100_0000 : exp_out[exp_lng-1:0];

assign data_out={sgnfc_out,exp_out_real};

endmodule