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Altera_Forum
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13 years ago

Using LPM DIVIDE inside VHDL Block

Hi, I am currently trying to implement Color Constancy algorithm for image processing. The algorithm requires at least one division operation (NUMER: 40 bits and DENOM: 40 bits). After scouting...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
13 years ago

Hi all,

A quick update: I am now able to implement my algorithm and it is working fine.

However, the amount of resources being used increased by 25% due to (inferred) division megafunction with compilation time of 8 minutes <- used to be 2.5 minutes. Is this expected? Can we optimise this?

Compiler by default setup LPM_DIVIDE parameter (as expected) to be:

Info (12134): Parameter "LPM_WIDTHN" = "40"

Info (12134): Parameter "LPM_WIDTHD" = "40"

Info (12134): Parameter "LPM_NREPRESENTATION" = "UNSIGNED"

Info (12134): Parameter "LPM_DREPRESENTATION" = "UNSIGNED"

Attached is code snippet for division, where all signals are 40 bits. 


when calc_RGB_dyn =>
      state <= wait_for_new_frame;
		
		-- Calculate dynamic RGB = normalise new RGB
        R_dyn_thresh <= ((R_thresh) / (normaliser));
        G_dyn_thresh <= ((G_thresh) / (normaliser));
        B_dyn_thresh <= ((B_thresh) / (normaliser));
		 
end case;

Vincent