s19frpackage.vhd

来自「ARM7核在FPGA中的VHDL代码实现」· VHDL 代码 · 共 45 行

-- *********************************************************************************************				  
-- Package for S19 file reader
-- Modified 07.02.2003
-- Designed by Ruslan Lepetenok
-- *********************************************************************************************				  

package S19FRPackage is
function LOG2(Number : positive) return natural;
function CharToNatural(InChar : character) return natural;
end S19FRPackage;

package body S19FRPackage is

function LOG2(Number : positive) return natural is
variable Temp : positive := 1;
begin
if Number=1 then 
 return 0;
  else 
   for i in 1 to integer'high loop
    Temp := 2*Temp; 
     if Temp>=Number then 
      return i;
     end if;
end loop;
end if;	
end LOG2;	

-- Converts symbols 0..9,A..F(a..f) to 
function CharToNatural(InChar : character) return natural is 
variable ArgTmpInt : natural := 0;
begin
if InChar>='0' and InChar<='9' then
 ArgTmpInt := character'pos(InChar)-character'pos('0');
  elsif InChar>='A' and InChar<='F' then
   ArgTmpInt := character'pos(InChar)-character'pos('A')+10;
   elsif InChar>='a' and InChar<='f' then	
    ArgTmpInt := character'pos(InChar)-character'pos('a')+10;
    else report"Error in hexadecimal" severity FAILURE;	   
	end if;	
return ArgTmpInt;
end CharToNatural;

end S19FRPackage;