substracting a whole array of values at once

CMOS · 2007-02-11T11:36:22+00:00

hi,i need a whole matrix to be substracted form another in one clockcycle.and i need to store all the values of these matrices in eitherdistributed or block RAM.i thought this is not possible with block RAM, as these have didicatedports that are fixed in width.so tried to use distributed RAM with the following verilog code.parameter nColumns = 100;parameter nRows = 200;parameter RAM_WIDTH = 8;//matrix 1 datareg [RAM_WIDTH-1:0] data_1[nColumns*nRows-1:0];//matrix 2 datareg [RAM_WIDTH-1:0] data_2[nColumns*nRows-1:0];reg [7:0] ix = 0;reg [7:0] iy = 0;reg[10:0] diff = 0;always @ (start) // start will trigger the calculationbeginfor(ix = 0; ix < 100; ix = ix + 1) begin for(iy = 0; iy < 100; iy = iy + 1) begin diff = diff +data_1[iy] - data_2[ix]; endendendise webpack completed stege one systhesis of this code after around 10minutes and did not complete the whole systhesis even after around 3hrs.any assistance is very much appreciated.thank you.

Feb 11, 2007 22 Replies

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CMOS 19 years ago

im not trying to proove a concept regarding SIMULTANIOUS SUBSTRACTION using FPGA's.

its bit more complicated and, this substraction thing (and total verilog code) is just a tool to prove it. thats why i dont bother about the best, most cost efficient way of doint it, as long as i can get results fast. and the code i mentioned is just an example. the actual matrix is maximum = 100 x 10, which allows me to do this in a real chip.

and i dont mind waiting for 100 milliseconds for the calculation, as the current calculation takes 3 seconds to complete. (this is using direct convolution, without doing FFT).

thank you.

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backhus 19 years ago

CMOS schrieb:

Hi CMOS, who named this thread "substracting a whole array of values at once"?

Why don't you tell us what your real problem is. Seems like my teasing was at least good for that purpose.

So you have a big algorithm that needs 3 seconds on some hardware unknown to us, and you need to speed it up? Ok, tell us more. But instead you post tiny fractions of the problem and misleading questions.

With my example I had no cost efficient solution in mind. Just an efficent one, and a practical one.

You say milliseconds is ok if you see that part as a single operation, well if you split that operation into small pieces (like adressing the matrix) you can do these operations within nanoseconds (like 100MHz Clockrate). Both approaches may solve the problem in the same total amount of calculating time, but you have much less problems implementing the 100MHz approach.

Give it a thougt and us better informations.

Best regards Eilert

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Pete Fraser 19 years ago

So why don't you speed things up by using the fequency domain (or are you a troll)?

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