TVecSmallInt.BlockInit Method

Initializes block processing.

Initializes block processing. Because the size of the CPU cache is limited, significant performance gains can be obtained by splitting long vectors in to a series of short ones, which can all fit in the CPU cache entirely. The BlockInit method is to be used together with Dew.Math.TMtxVecBase.BlockNext and Dew.Math.TMtxVecBase.BlockEnd methods to initialize a block processing while loop. BlockInit will call Dew.Math.TMtxVecBase.SetSubRange to obtain subrange of the data in TVec. The Dew.Math.TMtxVecBase.Length of the subranged vector is determined by the global Dew.Math.Units.Math387.MtxVecBlockSize variable declared in Math387 unit. Default value of MtxVecBlockSize is preset to 800 vector elements for double precision and 1600 elements for single precision. BlockInit supports nested calls and from witihin a blocked while loop you can call procedures and functions which are also blocked. If you use block processing, typical performance gains will range from 2 to a maximum of 6. Block processing can not be used, or it is difficult to apply, in cases where vector elements are not independent of each other. The block processing while loop must be written like this:

a.BlockInit;
while not A.BlockEnd do
begin
  // .... user defined function
a.BlockNext;
end;

Initializes block processing.

Block processing can be applied on possibly already subranged Src object. Src may not be freed or go out of scope until block processing loop has finished. There would be no error raised other than AV.

Initializes block processing.