📄 compressor.vhd
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DatoHeader := 0;
else
DatoHeader := DatoHeader + 1;
end if;
end case;
CompressingInt <= '1';
if ColumnToCompress = "0000000000" then --we've changed line, careful
--because we have to process the last block of the previous line
Linea := (not LineToCompress(3)) & "000";
Columna := ImgColumns(9 downto 3) & "000";
else
Linea := LineToCompress(3) & "000";
Columna := (ColumnToCompress(9 downto 3) - 1) & "000";
end if;
Bloque := ColumnToCompress(1 downto 0);
StepV <= 0;
weY2 <= '0';
weCb2 <= '0';
weCr2 <= '0';
Coeficiente := 0;
Save <= '0';
IniDC := '1';
GetPrevDC := '1';
WriteAdditionalBits <= '0';
else
we <= '0';
LumaBlock := Bloque(1) nor Bloque(0); --it is 1 if we are dealing with luminance component
--It is necessary that Base be here so that it changes when Bloque changes in the "if" of Done in the last image's block
if Bloque = "00" then --Q Coefficients of Table 0 (luminance)
BaseH := (others => '0'); --address 0 of Huffman Luminance Table
case Compression is
when "00" => --Low Quality
Base := "100000000";
when "01" => --Medium Quality
Base := "010000000";
when others => --10 High Quality
Base := "000000000";
end case;
else --Q Coefficients of Table 1 (chroma)
BaseH := "010110000"; --address 0 of Huffman Chrominance Table
case Compression is
when "00" => --Low Quality
Base := "101000000";
when "01" => --Medium Quality
Base := "011000000";
when others => --10 High Quality
Base := "001000000";
end case;
end if;
case StepV is
when 0 => --with the first data to let addrXX2 load and have the data in memory
weY2 <= '0';
weCb2 <= '0';
weCr2 <= '0';
if CompressingInt = '1' and Done = '0' then --Done=0 cause in case it is a Y block (but not the fourth (the last)) coming from StepV=3
StepV <= 1;
else
StepV <= 0;
end if;
NDe <= '0';
RFDInt <= '0';
when 1 => --Feeding of DCT1 with 64 pixels
if RFD = '1' then --DCT1 ready for data (RFD)
NDe <= '1';
ND <= NDe; --this way we delay ND one cycle to synchronize data
if RFDInt = '0' then
case Bloque is
when "00" => --block Y
DIND <= doutY(7 downto 0);
when "01" => --block Cb
DIND <= doutCb(7 downto 0);
when others => --can only be block Cr
DIND <= doutCr(7 downto 0);
end case;
else
DIND <= RFDIntData; --to recover the "lost" cycle because RFD was 0 (if the DCT was such that RFD were 0 for more than a cycle it would be necessary to change this part)
RFDInt <= '0';
end if;
if Columna(2 downto 0) = "111" then
Columna := Columna(9 downto 3) & "000";
Linea := Linea + 1;
if Linea(2 downto 0) = "000" then --we've finished this StepV, now we'll wait for the results
StepV <= 2; --we shall go to StepV 2 with the first column of the block
Linea(3) := not Linea(3); --makes it rest in current block
Primera := '1'; --to not let StepV 2 change Linea or Column in its 1st cycle because they already have adequate values
end if;
else
Columna := Columna + 1;
end if;
else
--to not lose the just read pixel (rememer that reads are ahead of their time!!)
RFDInt <= '1';
case Bloque is
when "00" => --block Y
RFDIntData <= doutY(7 downto 0);
when "01" => --block Cb
RFDIntData <= doutCb(7 downto 0);
when others => --can only be block Cr
RFDIntData <= doutCr(7 downto 0);
end case;
--ND <= '0';
end if;
weY2 <= '0';
weCb2 <= '0';
weCr2 <= '0';
addrQ <= Base; --DC Coefficient's Q (Base + Linea*8 + Columna)
QDC := (others => '0');
when 2 => --we receive the data, quantize it, truncate it and save them back to the buffer
--watch out because DCT1 outputs data column-wise (feeding was row-wise)
NDe <= '0'; --it stayed high while sending data byte
ND <= NDe;
case Bloque is --needed to send the last data of the block (it is alright!!!)
when "00" => --block Y
DIND <= doutY(7 downto 0);
when "01" => --block Cb
DIND <= doutCb(7 downto 0);
when others => --can only be block Cr
DIND <= doutCr(7 downto 0);
end case;
if RDY = '1' then --output data ready!!
if QDC /= 0 then
DCTQ := MultiplierQ(DOUTD(14 downto 3), QDC);
QDC := (others => '0');
else
DCTQ := MultiplierQ(DOUTD(14 downto 3), DOUTQ); --multiply the DCT coefficient times Qyx fraction's numerator
end if;
--if DCTQ(24) = '0' then --it is positive, let's round
DCTQ(24 downto 14) := DCTQ(24 downto 14) + DCTQ(13); --round to nearest integer
--end if;
--if DCTQ(24 downto 13) = "111111111111" then --it is less or equal than -0.5, roung to 0
-- DCTQ(24 downto 13) := "000000000000"; --or else it will be read as -1
--end if;
case Bloque is --the "+ DCTQ(13)" is the nearest integer round!
when "00" => --block Y
dinY2 <= DCTQ(24) & DCTQ(24 downto 14);-- + DCTQ(13); --we divide (shifting right) by the general Q coefficient denominator (16384) and save the quantized coefficient
--sign-extension
weY2 <= '1';
when "01" => --block Cb
dinCb2 <= DCTQ(24) & DCTQ(24 downto 14);-- + DCTQ(13); --we divide (shifting right) by the general Q coefficient denominator (16384) and save the quantized coefficient
weCb2 <= '1';
when others => --can only be block Cr
dinCr2 <= DCTQ(24) & DCTQ(24 downto 14);-- + DCTQ(13); --we divide (shifting right) by the general Q coefficient denominator (16384) and save the quantized coefficient
weCr2 <= '1';
end case;
--write column-wise
if Linea(2 downto 0) = "111" and Primera = '0' then --have we reached this line's end?
--Primera is used for the first cycle of StepV2 in which Columna and Linea arrive with the right value
--so they need not be changed in order to get the correct address
Linea := Linea(3) & "000";
Columna := Columna + 1;
else
if Primera = '1' then
Primera := '0';
else
Linea := Linea + 1;
if Linea(2 downto 0) = "111" and Columna(2 downto 0) = "111" then --we have finished this StepV, now we must Huffman encode
StepV <= 3;
end if;
end if;
end if;
--the following code is because we must load one cycle early the addrQ so that in the
--current cycle we can have the right Q coefficient for current Linea and Columna values
if Linea(2 downto 0) = "110" then --have we reached the end?
--next coeff. is Linea 0 of the Coeff. Table and Columna is current plus one
addrQ <= Base + Columna(2 downto 0) + 2; --Base + Linea*8 + Columna --> remember coefficient table is 8x8
else
--next coeff is next Linea of the Coeff. Table and current Columna
addrQ <= Base + ((Linea(2 downto 0) + 2) & "000") + Columna(2 downto 0); --Base + Linea*8 + Columna
end if;
else
--during Latency cycles we will be here waiting until RDY is 1
--and also every X cycles when RDY becomes 0 for one cycle
if QDC = 0 and addrQ = Base then --only happens when we enter this StepV from the previous one
QDC := DOUTQ; --save the DC value because Q reading must be ahead by two cycles now
addrQ <= Base + "1000"; --Base + Linea*8 + Columna (Linea=1, Columna=0)
end if;
weY2 <= '0';
weCr2 <= '0';
weCb2 <= '0';
end if;
when 3 =>
weY2 <= '0';
weCr2 <= '0';
weCb2 <= '0';
--Make the "pointers" Linea and Columna point to the beginning of the next block
--must do it here because in the last cycle of StepV2, when StepV becomes 3, Linea and Columna
--must maintain their value
Linea := Linea(3) & "000";
Columna := Columna + 1;
if LumaBlock = '1' then --if we are processing the luminance block we can only save it when we have processed the 4 ones
--that compose the 2x2 block of subsampling, there is no problem with the order of the chroma ones because these ones too
--are saved when we have averaged four and that is controlled by the process RGB2YCbCr
if Linea(3) = '1' and Columna(3) = '0' then --checked, it is alright (remember it points to the next block)
StepV <= 4;
Elemento := "00"; --process the first square (8x8 block) of the 2x2 luminance block (16x16 pixels, 2x2 squares)
--Ready Linea and Columna to read element 00 that Huffman will receive
Linea := (others => '0');
Columna := (Columna(9 downto 4) - 1) & "0000";
else --the three first squares of the 2x2 luminance block are not sent to Huffman yet (subsampling requirements)
StepV <= 0;
Done <= '1';
end if;
else
Columna := Columna - 1;
Columna := Columna(9 downto 3) & "000"; --it is alright, because Columna arrives already adjusted to Cb and Cr.
StepV <= 4;
end if;
WriteAdditionalBits <= '0';
when 4 => --with this dummy cycle we give time to the memory to give us address 0
--for the DC coefficient
weY2 <= '0';
weCr2 <= '0';
weCb2 <= '0';
Save <= '0'; --just in case we left it high in last step
we <= '0';
StepV <= 5;
when 5 => --Linea and Columna point to the beginning of the block
--If we change Linea and/or Columna in cycle 0 of this section, then the new address will
--be sent to memory in cycle 1 and in cycle 2 doutX will have the asked data, so careful!!
case Bloque is
when "00" => --block Y
Coef := doutY;
when "01" => --block Cb
Coef := doutCb;
when others => --can only be block Cr
Coef := doutCr;
end case;
we <= '0';
if Done = '0' then --this way it does not go to look for the DC when we change Block (upsetting FirstDC)
if Save = '0' then
if WriteAdditionalBits = '0' then
if Coeficiente = 0 then
--The previous component is read from the buffer varying Linea and Columna
if IniDC = '1' then --we've not yet obtained the previous DC to calculate the difference
if Linea = "0000" and Columna = "000000000" and FirstDC = '1' and GetPrevDC = '1' then --must do it this way
--or else the luminance, which has 4 blocks in its first Huffmanear takes DC=0 for all
--GetPrevDC = 1 is so that execution doesnt get here if in the previous cycle GetPrevDC became zero in the bottom "if"
--and put Linea and Columna to zero
--we are in the first block of the image, PrevDC is zero
if Bloque = "10" then --if we are in the last, we zero it
FirstDC := '0'; --because it has already been used by the three components (Y,Cb,Cr)
end if;
PrevDC := (others => '0');
IniDC := '0';
else
if GetPrevDC = '1' then
ColBk := Columna; --save the values of Linea and Columna
LinBk := Linea;
--Must obtain the quantized DC coefficient of the last processed block
--as stated by specification, but actually the last block is indicated by MCU
if Columna(9 downto 3) = "0000000" then --first block of the row?
if LumaBlock = '1' then
if Elemento = "00" then
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