Mill Computing, Inc. Forums The Mill Architecture Vector ops Reply To: Vector ops

goldbug
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Post count: 52

My shot at this using alternate:

 
// %0 contains [0,0,1,0]
// %1 contains [A,B,C,D]
F("pick_reduce_4") %0, %1;  
   pick      (%0, %1)        %2;     
   
   alternate (%2, %2)        %3 %4,
   recur     (%3, %4, %3)    %5;

   alternate (%5, %5)        %6 %7,
   recur     (%6, %7, %6)    %8;

   extract   (%8, w(0ul))   %9
   ret       (%9);

Some example runs:


   input: %0 = [1,0,0,0] %1 = [a,b,c,d]

   %2 = [a,,,]
   %3 = [a,a,,]   %4=[,,,]
   %5 = [a,a,,]
   %6 = [a,a,a,a] %7=[,,,]
   %8 = [a,a,a,a]
   %9 = a

   input: %0 = [0,1,0,0] %1 = [a,b,c,d]

   %2 = [,b,,]
   %3 = [,,b,b]      %4=[,,,]
   %5 = [,,b,b]
   %6 = [,,,]        %7=[b,b,b,b]
   %8 = [b,b,b,b]
   %9 = b

   input: %0 = [0,0,1,0] %1 = [a,b,c,d]

   %2 = [,,c,]
   %3 = [,,,]      %4=[c,c,,]
   %5 = [c,c,,]
   %6 = [c,c,c,c]  %7=[,,,]
   %8 = [c,c,c,c]
   %9 = c

   input: %0 = [0,0,0,1] %1 = [a,b,c,d]

   %2 = [,,,d]
   %3 = [,,,]      %4=[,,d,d]
   %5 = [,,d,d]
   %6 = [,,,]      %7=[d,d,d,d]
   %8 = [d,d,d,d]
   %9 = d

Shuffle is to reorder a vector? If I understand it correctly:


    shuffle ([a,b,c,d],  [3,2,1,0])  =  [d,c,b,a]
    shuffle ([a,b,c,d],  [1,1,1,1])  =  [b,b,b,b]
    shuffle ([a,b,c,d], [0, None, None, None]) = [a, None, None, None]

Then perhaps we can use the left operation to find the index of the selected element, this should work for vectors of any size and it would be O(1):


F("pick_reduce") %0, %1;  
   left       (%0)           %2;

   // this just builds a vector the same width as the data vector
   // the first element is the index of the element we want
   // the rest do not matter and can be junk
   inject     (%1, %2, 0)    %3;
   
   shuffle    (%1, %3)       %4;

   extract    (%4, 0)        %5,
   ret        (%5);   

If I understand correctly, the left operation will return the amount of leading zeroes. So if %0 = [0,0,1,0], then %2 will be 2.
Then I create a vector with that result as the first element in %3 and use that to shuffle the input vector, the first element in the result will be the element at position 2.

Is this correct Ivan?

  • This reply was modified 4 years, 11 months ago by  goldbug.
  • This reply was modified 4 years, 11 months ago by  goldbug.
  • This reply was modified 4 years, 11 months ago by  goldbug.