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URL https://opencores.org/ocsvn/deflatecore/deflatecore/trunk

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/trunk/HashChain.vhd
30,81 → 30,15
Output_E : in bit -- Output Enable
);
end HashChain;
 
 
--From Robert Sedgwicks Algorithms in C
architecture RSHash of HashChain is
signal mode: integer;
begin
mode <= 0 when clock = '1' and reset = '0' and Output_E = '1' else -- Active data being latched to output
1 when clock = '0' and reset = '0' and Output_E = '1' else -- No change to output till thge next clock
2 when clock = '1' and reset = '1' and Output_E = '1' else -- Reset active
2 when clock = '1' and reset = '1' and Output_E = '0' else -- Reset active
3 when clock = '1' and reset = '0' and Output_E = '0' else -- Disable output
4;
 
Process (mode)
variable a, b, hash : std_logic_vector (Hash_Width -1 downto 0); -- Variables for calculating the output
begin
case mode is
when 0 => --Calculate the hash key of the current input value using the input data
hash := hash * a;
hash := hash + Data_in;
a := a * b;
when 2 =>
hash := X"0000_0000"; -- Reset hash value to 0
a:=X"0005_C6B7"; -- Reset a to 378551
b:=X"0000_F8C9"; -- Reset b to 63689
when 3=> -- Need to implement a disable output section
 
when OTHERS => -- Do nothing
 
End case;
hash_o<= hash; -- Latch the calculated hash value to the output
end process;
end RSHash;
 
--An algorithm produced by Professor Daniel J. Bernstein and
--shown first to the world on the usenet newsgroup comp.lang.c.
--It is one of the most efficient hash functions ever published
--Actual function hash(i) = hash(i - 1) * 33 + str[i];
architecture DJB of HashChain is
signal mode: integer;
 
begin
mode <= 0 when clock = '1' and reset = '0' and Output_E = '1' else -- Active data being latched to output
1 when clock = '0' and reset = '0' and Output_E = '1' else -- No change to output till thge next clock
2 when clock = '1' and reset = '1' and Output_E = '1' else -- Reset active
2 when clock = '1' and reset = '1' and Output_E = '0' else -- Reset active
3 when clock = '1' and reset = '0' and Output_E = '0' else -- Disable output
4;
 
Process (mode)
variable a, b, hash :std_logic_vector (Hash_Width - 1 downto 0); -- Variables for calculating the output
begin
case mode is
when 0 => --Calculate the hash key of the current input value using the Data on the input vector
a := hash * X"21"; --Multiply the hash value by 33
hash := a + hash + Data_in; --Add the above value to the previous hash and add the input data
when 2 => --Reset
hash := X"16c7"; --Reset initial hash value to 5831
when 3=> -- Need to implement a disable output section
 
when OTHERS => -- Do nothing
 
End case;
hash_o<= hash; -- Latch the clculated hash value to the output
end process;
end DJB;
 
--An algorithm produced by Professor Daniel J. Bernstein and
--shown first to the world on the usenet newsgroup comp.lang.c.
--It is one of the most efficient hash functions ever published
--Actual function hash(i) = hash(i - 1) * 33 + str[i];
--Function now implemented using XOR hash(i) = hash(i - 1) * 33 ^ str[i];
architecture DJB2 of HashChain is
signal mode: integer;
 
signal tempval:std_logic_vector (Hash_Width - 1 downto 0);
begin
mode <= 0 when clock = '1' and reset = '0' and Output_E = '1' else -- Active data being latched to output
1 when clock = '0' and reset = '0' and Output_E = '1' else -- No change to output till thge next clock
119,7 → 53,10
case mode is
when 0 => --Calculate the hash key of the current input value using the Data on the input vector
a := hash * X"21"; --Multiply the hash value by 33
hash := (a + hash) xor Data_in; --Add the above value to the previous hash and add the input data
b := X"00000000";
b := b + Data_in;
tempval <= a+hash;
hash := tempval xor b; --Add the above value to the previous hash and add the input data
when 2 => --Reset
hash := X"16c7"; --Reset initial hash value to 5831
when 3=> -- Need to implement a disable output section
130,51 → 67,18
hash_o<= hash; -- Latch the clculated hash value to the output
end process;
end DJB2;
--This algorithm was created for sdbm (a public-domain reimplementation of ndbm) database library.
--it was found to do well in scrambling bits, causing better distribution of the keys and fewer splits.
--it also happens to be a good general hashing function with good distribution.
--the actual function is hash(i) = hash(i - 1) * 65599 + str[i];
architecture sdbm of HashChain is
signal mode: integer;
 
begin
mode <= 0 when clock = '1' and reset = '0' and Output_E = '1' else -- Active data being latched to output
1 when clock = '0' and reset = '0' and Output_E = '1' else -- No change to output till thge next clock
2 when clock = '1' and reset = '1' and Output_E = '1' else -- Reset active
2 when clock = '1' and reset = '1' and Output_E = '0' else -- Reset active
3 when clock = '1' and reset = '0' and Output_E = '0' else -- Disable output
4;
 
Process (mode)
variable a, b, hash : std_logic_vector (Hash_Width - 1 downto 0); -- Variables for calculating the output
begin
case mode is
when 0 => --Calculate the hash key of the current input value using the Data on the input vector
a := hash * X"1003f"; --Multiply the previous hash with 65599
hash := a + hash + Data_in; --Add the above result to theprevious hash and add the input data
when 2 =>
hash := X"0"; -- Reset
when 3=> -- Need to implement a disable output section
 
when OTHERS => -- Do nothing
 
End case;
hash_o<= hash; -- Assign the clculated hash value to the output
end process;
end sdbm;
 
--Configuration:
--Assign the name of the algorithm as the configuration.
 
Configuration rs_hash of hashchain is
for rshash
end for;
end rs_hash;
--Configuration rs_hash of hashchain is
--for rshash
--end for;
--end rs_hash;
 
Configuration djb_hash of hashchain is
for djb
end for;
end djb_hash;
--Configuration djb_hash of hashchain is
--for djb
--end for;
--end djb_hash;
 
Configuration djb2_hash of hashchain is
for djb2
181,8 → 85,8
end for;
end djb2_hash;
 
Configuration sdbm_hash of hashchain is
for sdbm
end for;
end sdbm_hash;
--Configuration sdbm_hash of hashchain is
--for sdbm
--end for;
--end sdbm_hash;
 

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