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URL https://opencores.org/ocsvn/lzrw1-compressor-core/lzrw1-compressor-core/trunk

Subversion Repositories lzrw1-compressor-core

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  • This comparison shows the changes necessary to convert path 
    /lzrw1-compressor-core/trunk/hw/HDL
    from Rev 2 to Rev 3
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  •

Rev 2 → Rev 3

/LZRWcompressor.vhd
178,7 → 178,7
signal Candidate2xDN, Candidate2xDP : std_logic_vector(LOOK_AHEAD_LEN*8-1 downto 0) := (others => '0');
signal NextWrAdr2xDN, NextWrAdr2xDP : integer range 0 to LOOK_AHEAD_LEN := 0;
signal CandAddr2xDN, CandAddr2xDP : std_logic_vector(11 downto 0) := (others => '0');
signal CandLen2xD : integer range 0 to LOOK_AHEAD_LEN;
signal CandLen2xDN, CandLen2xDP : integer range 0 to LOOK_AHEAD_LEN;
signal EndOfData2xSN, EndOfData2xSP : std_logic := '0';
signal OffsetIntxD : integer range -HIST_BUF_LEN to HIST_BUF_LEN;
signal OffsetxD : std_logic_vector(11 downto 0);
213,15 → 213,15
Strobe0xSN <= '0';
EndOfData0xSN <= '0';
DataIn0xDN <= DataIn0xDP;
BusyxSN <= '0';
BusyxSN <= '0';
 
case StatexSP is
when ST_FILL_LOOK_AHEAD =>
-- don't shift here, we are still loading data
--ShiftLookAheadxSN <= StrobexSI; -- the shift is delayed by one cycle because we have to process the byte first
WrHistBufxS <= StrobexSI;
DataIn0xDN <= DataInxDI;
if FlushBufxSI='1' then
WrHistBufxS <= StrobexSI;
DataIn0xDN <= DataInxDI;
if FlushBufxSI = '1' then
StatexSN <= ST_DRAIN_LOOK_AHEAD;
elsif LookAheadLenxDP = LOOK_AHEAD_LEN-1 then
-- this byte is number look_ahead_len-1, so it is the last one before the buffer is full
256,7 → 256,7
end case;
 
if OutFIFOLengthxD > OUT_FIFO_THR then
BusyxSN <= '1'; -- request stop of data input if output FIFO is full
BusyxSN <= '1'; -- request stop of data input if output FIFO is full
end if;
end process;
 
293,7 → 293,7
process (DataInxDI, LookAheadLenxDP, ShiftLookAheadxSP, StrobexSI,
lookAheadBufxDP)
begin -- process
lookAheadBufxDN(i) <= lookAheadBufxDP(i); -- default: do nothing
lookAheadBufxDN(i) <= lookAheadBufxDP(i); -- default: do nothing
if ShiftLookAheadxSP = '1' then
lookAheadBufxDN(i) <= lookAheadBufxDP(i+1); -- shift done one entry
elsif LookAheadLenxDP = i and StrobexSI = '1' then
400,27 → 400,32
MaxCandLenxD <= LOOK_AHEAD_LEN;
 
-- use a shifter to implement the last two bytes of the address
process (CandAddr1xDP, CandAddr2xDP, Candidate2xDP, HistBufLen1xDP,
HistBufLen2xDP, HistBufOutxD, LookAheadBuf1xDP, LookAheadBuf2xDP,
LookAheadLen1xDP, LookAheadLen2xDP, LookAheadPtr1xDP, MaxCandLenxD,
Strobe1xSP)
process (CandAddr1xDP, CandAddr2xDP, CandLen2xDP, Candidate2xDP,
HistBufLen1xDP, HistBufLen2xDP, HistBufOutxD, LookAheadBuf1xDP,
LookAheadBuf2xDP, LookAheadLen1xDP, LookAheadLen2xDP,
LookAheadPtr1xDP, LookAheadPtr2xDP, MaxCandLenxD, Strobe1xSP)
begin
Candidate2xDN <= Candidate2xDP;
LookAheadBuf2xDN <= LookAheadBuf2xDP;
LookAheadLen2xDN <= LookAheadLen2xDP;
CandAddr2xDN <= CandAddr2xDP;
LookAheadPtr2xDN <= LookAheadPtr2xDP;
HistBufLen2xDN <= HistBufLen2xDP;
 
CandLen2xDN <= CandLen2xDP;
-- send data through pipeline when strobe is high
if Strobe1xSP = '1' then
-- note: the history buffer can't load data only from addresses where the
-- last two bits are zero. If this was not the case we shift the candidate
-- (which makes it shorter) to correct that
case CandAddr1xDP(1 downto 0) is
when "00" => Candidate2xDN <= HistBufOutxD; -- no shifting
CandLen2xD <= MaxCandLenxD;
CandLen2xDN <= MaxCandLenxD;
when "01" => Candidate2xDN <= x"00" & HistBufOutxD(LOOK_AHEAD_LEN*8-1 downto 8); -- shift one byte
CandLen2xD <= MaxCandLenxD-1; -- we shifted one byte out -> candidate is one byte shorter
CandLen2xDN <= MaxCandLenxD-1; -- we shifted one byte out -> candidate is one byte shorter
when "10" => Candidate2xDN <= x"0000" & HistBufOutxD(LOOK_AHEAD_LEN*8-1 downto 16); -- shift 2 bytes
CandLen2xD <= MaxCandLenxD-2;
CandLen2xDN <= MaxCandLenxD-2;
when "11" => Candidate2xDN <= x"000000" & HistBufOutxD(LOOK_AHEAD_LEN*8-1 downto 24); -- shift 3 bytes
CandLen2xD <= MaxCandLenxD-3;
CandLen2xDN <= MaxCandLenxD-3;
when others => null;
end case;
 
457,7 → 462,7
LookAheadxDI => CompLAIn3xD,
LookAheadLenxDI => LookAheadLen2xDP,
CandidatexDI => Candidate2xDP,
CandidateLenxDI => CandLen2xD,
CandidateLenxDI => CandLen2xDP,
MatchLenxDO => MatchLenxD);
 
-- calculate the offset
574,6 → 579,7
LookAheadPtr2xDP <= LookAheadPtr2xDN;
CandAddr2xDP <= CandAddr2xDN;
Candidate2xDP <= Candidate2xDN;
CandLen2xDP <= CandLen2xDN;
HashTableEntry2xDP <= HashTableEntry2xDN;
EndOfData0xSP <= EndOfData0xSN;
EndOfData1xSP <= EndOfData1xSN;

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