8_bitpkg.vhd

北京里工大学ASIC设计研究所的100个 VHDL程序设计例子

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PACKAGE bit_rtl_pkg is
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   subtype short is integer  range 0 to 65535;

   subtype int4  is integer  range 0 to 16;

   subtype int8  is integer  range 0 to 255;
	

   function bit_to_int (in1:bit_vector) 
	  return integer;

   function int_to_bit1( aa3: integer;len:integer) 
	  return bit_vector;

   function int_to_bit (in1:integer) 
	  return bit_vector;

   function "+" ( in1, in2 : bit_vector ) 
	  return integer;

   function "+" ( in1, in2 : bit_vector ) 
	  return bit_vector;

   function "+" ( in1: bit_vector;in2: integer ) 
	  return bit_vector;

   function "-" ( in1, in2: bit_vector ) 
	  return integer;

   function "-" ( in1, in2 : bit_vector ) 
	  return bit_vector;

   function "-" ( in1: bit_vector;in2: integer ) 
	  return bit_vector;

   function "*" ( in1,in2: bit_vector ) 
	  return bit_vector;
 
   function "*" ( in1,in2: bit_vector ) 
	  return integer;

   function "/" ( in1,in2: bit_vector ) 
	  return bit_vector;
 
   function "/" ( in1,in2: bit_vector ) 
	  return integer;

end bit_rtl_pkg;

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PACKAGE BODY bit_rtl_pkg is
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  function bit_to_int (in1:bit_vector) return integer is
	   ALIAS v1: BIT_VECTOR(in1'LENGTH-1 DOWNTO 0) IS in1;
	   variable inpv : bit_vector(in1'LENGTH-1 DOWNTO 0 );
       variable SUM: integer := 0;
	   variable negative :boolean:= false;
  begin
	   inpv := in1;
	   if  v1(v1'length-1) = '1' then
          for i in v1'length-1 downto 0 loop
			 inpv(i) := not inpv(i);
		  end loop;
	      lp1: 
		  for i in 0 to v1'length-1 loop
			  if  inpv(i) = '1' THEN
				 inpv(i) := '0';
              else 
				 inpv(i) := '1';
				 exit lp1; 
			  end if;
		  end loop;
		  negative := true;
       end if;

       for i in v1'length-1 downto 0 loop
         if inpv(i) = '1' then
            SUM := SUM + 2**i;
         end if;
       end loop;

       if negative then
          return (0-SUM);
       else
		  return SUM;
	   end if;
   end bit_to_int; 

   function log2( in1: integer )
   return integer 
   is
   begin
		return 1;
   end;

   function int_to_bit1( aa3: integer;len:integer) return bit_vector is 
		variable i,aa4: integer;
		variable j    : integer;
		--variable digit1: integer:=2**(len-1);
		variable result1 :bit_vector((len-1) downto 0);
   begin

		i:=0;

		if  aa3 < 0 then
		   aa4 := 0-aa3;
        else 
		   aa4:=aa3;
        end if;

		while(aa4>0) loop
		   if ( aa4 mod 2 = 1 )  then
		      result1(i) := '1' ;
           else
			  result1(i) := '0';
           end if;
           i:=i+1;
		   aa4 := aa4/2;
        end loop;
		j:=len-1;
		for j in len-1 downto i loop
		   result1(j) := '0';
        end loop;

		if (aa3<0) then
           for i in len-1 downto 0 loop
			  result1(i) := not result1(i);
           end loop;
		   lp1:
		   for i in 0 to len-1 loop
			  if  result1(i) = '1' THEN
				 result1(i) := '0';
              else 
				 result1(i) := '1';
				 exit lp1;
              end if;
           end loop;
		end if;

	    --   for i in (len-1) downto 0 loop
		--  if aa4 >= digit1 then
	    --         result1(i):='1';
        --             aa4 := aa4 - digit1;
		--  else
		--     result1(i):='0';
		--  end if;
		--  digit1:=digit1/2;
        --       end loop;

        return result1;
   end int_to_bit1;

   function int_to_bit (in1:integer) 
   return bit_vector 
   is
       variable temp: integer;
       variable digit: integer;
	   variable i    : integer;
       variable result :bit_vector( log2(in1) downto 0);
   begin
       temp:=in1;
	   i   :=0;
	   result:= "000000000000000000000000000000000";
	   while (temp > 0) loop
		  digit := temp mod 2;
		  if ( digit = 1) then
			 result(i) := '1';
          else
			 result(i) := '0';
          end if;
		  i:=i+1;
		  temp := temp /2;
       end loop;
       return result;
   end int_to_bit;

   function "+" ( in1, in2 : bit_vector ) 
   return integer 
   is
   begin
     return(bit_to_int(in1)+bit_to_int(in2));
   end "+";

   function "+" ( in1, in2 : bit_vector ) return bit_vector is
   begin
     return (int_to_bit1( 
		bit_to_int(in1)+ bit_to_int(in2),in1'length
			 ));
   end "+";

   function "+" ( in1 : bit_vector;in2:integer ) 
   return bit_vector is
   begin
     return(int_to_bit1(bit_to_int(in1)+in2,in1'length));
   end "+";

   function "-" ( in1, in2 : bit_vector ) return integer is
   begin
     return(bit_to_int(in1)-bit_to_int(in2));
   end "-";

   function "-" ( in1, in2 : bit_vector ) return bit_vector is
   begin
     return(int_to_bit1(bit_to_int(in1)- bit_to_int(in2),in1'length));
   end "-";

   function "-" ( in1 : bit_vector;in2:integer ) 
   return bit_vector is
   begin
     return(int_to_bit1(bit_to_int(in1)-in2,in1'length));
   end "-";

   function "*" ( in1, in2 : bit_vector ) return integer is
   begin
     return( bit_to_int(in1)*bit_to_int(in2) );
   end "*";

   function "*" ( in1, in2 : bit_vector ) return bit_vector is
   begin
     return( int_to_bit1( bit_to_int(in1)*bit_to_int(in2),in1'length ));
   end "*";

   function "/" ( in1, in2 : bit_vector ) return integer is
   begin
     return(bit_to_int(in1)/ bit_to_int(in2));
   end "/";

   function "/" ( in1, in2 : bit_vector ) return bit_vector is
   begin
     return(int_to_bit1(bit_to_int(in1)/ bit_to_int(in2),in1'length));
   end "/";

end bit_rtl_pkg;