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library ieee;
use ieee.std_logic_1164.all;
package DataStructures is
-- Simple hashing functions
function Modulo_Int (d : integer; size : positive) return natural;
function Modulo (d : string; size : positive) return natural;
-- Dictionaries
package Integer_Integer_Dict_Pkg is new work.corelib_Dict
generic map (KEY_TYPE => integer,
VALUE_TYPE => integer,
to_hash => Modulo_Int);
package Integer_StdLogicVector_Dict_Pkg is new work.corelib_Dict
generic map (KEY_TYPE => integer,
VALUE_TYPE => std_logic_vector,
to_hash => Modulo_Int);
package String_String_Dict_Pkg is new work.corelib_Dict
generic map (KEY_TYPE => string,
VALUE_TYPE => string,
to_hash => Modulo);
package String_StdLogicVector_Dict_Pkg is new work.corelib_Dict
generic map (KEY_TYPE => string,
VALUE_TYPE => std_logic_vector,
to_hash => Modulo);
-- Aliases for convenience reasons
alias Integer_Integer_Dict is Integer_Integer_Dict_Pkg.PT_DICT;
alias Integer_Slv_Dict is Integer_StdLogicVector_Dict_Pkg.PT_DICT;
alias String_String_Dict is String_String_Dict_Pkg.PT_DICT;
alias String_Slv_Dict is String_StdLogicVector_Dict_Pkg.PT_DICT;
end package;
package body DataStructures is
-- Simple modulo function for integers
function Modulo_int (d : integer; size : positive) return natural is
begin
return d mod size;
end function Modulo_Int;
-- Simple modulo function for ISO 8859 Latin-1 8-bit strings
-- of arbitrary length (>= VHDL 93)
function Modulo (d : string; size : positive) return natural is
variable hash : natural := 0;
begin
assert size <= ((natural'high - 255) / 256 + 1)
report Modulo[string, natural return natural]'instance_name & ": size parameter too large, possible overflow"
severity failure;
for i in d'range loop
hash := (hash * 256 + Character'Pos (d(i))) mod size;
end loop;
return hash;
end function Modulo;
end package body DataStructures;
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