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Altera_Forum
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10 years ago

Fmax Improvment

I'm trying to improve Fmax in our design. See the archived quartus II proejct file in the attachment. The source files are also attached. In my currrent design, after compilation, Fmax can reach ...
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Altera_Forum
Icon for Honored Contributor rankHonored Contributor
10 years ago

Thank you. Tricky and flz476555. I already change my code with "unsigned" to make it more readable as below.

In my code, there is a long "if" + "elsif" chain which has lower Fmax very much. Do you have any idea to optimize the code if adding pipeline is not an option? 

signal Setting_TotPixel : unsigned(15 downto 0) := (others=>'0');
signal Setting_Pixel 	: unsigned(15 downto 0) := (others=>'0');
		-- Gray bar(16 gray bars)
      	HelperGrayBar <= "1111"; -- gray level 15	
      	if Setting_Pixel < (Setting_TotPixel/16) then
      		HelperGrayBar <= "0000"; -- black
      	elsif Setting_Pixel < (Setting_TotPixel/8)  then
      		HelperGrayBar <= "0001"; -- gray level 1
			elsif Setting_Pixel < ((Setting_TotPixel/8)  + (Setting_TotPixel/16)) then
      		HelperGrayBar <= "0010"; -- gray level 2
      	elsif Setting_Pixel < (Setting_TotPixel/4)  then
      		HelperGrayBar <= "0011"; -- gray level 3
			elsif Setting_Pixel < ((Setting_TotPixel/4)) + ((Setting_TotPixel/16)) then
      		HelperGrayBar <= "0100"; -- gray level 4
			elsif Setting_Pixel < ((Setting_TotPixel/4)) + ((Setting_TotPixel/8)) then
      		HelperGrayBar <= "0101"; -- gray level 5
			elsif Setting_Pixel < ((Setting_TotPixel/2) - (Setting_TotPixel/16)) then
      		HelperGrayBar <= "0110"; -- gray level 6
			elsif Setting_Pixel < (Setting_TotPixel/2) then
      		HelperGrayBar <= "0111"; -- gray level 7
			elsif Setting_Pixel < ((Setting_TotPixel/2) + (Setting_TotPixel/16)) then
      		HelperGrayBar <= "1000"; -- gray level 8
			elsif Setting_Pixel < ((Setting_TotPixel/2) + (Setting_TotPixel/8)) then
      		HelperGrayBar <= "1001"; -- gray level 9
			elsif Setting_Pixel < ((Setting_TotPixel/2) + (Setting_TotPixel/8) + (Setting_TotPixel/16)) then
      		HelperGrayBar <= "1010"; -- gray level 10
			elsif Setting_Pixel < ((Setting_TotPixel/2) + (Setting_TotPixel/4)) then
      		HelperGrayBar <= "1011"; -- gray level 11
			elsif Setting_Pixel < ((Setting_TotPixel/2) + (Setting_TotPixel/4) + (Setting_TotPixel/16)) then
      		HelperGrayBar <= "1100"; -- gray level 12
			elsif Setting_Pixel < ((Setting_TotPixel/2) + (Setting_TotPixel/4) + (Setting_TotPixel/8)) then
      		HelperGrayBar <= "1101"; -- gray level 13
			elsif Setting_Pixel < (Setting_TotPixel - (Setting_TotPixel/16)) then
      		HelperGrayBar <= "1110"; -- gray level 14
      	end if;