MEL PICBASIC Forum - Sorting Numbers

  • Sorting Numbers

    by
    Melanie
    Published on - 2nd July 2010 16:35  Number of Views: 8650  
    In professional embedded applications, when you take an ADC reading, good practice states that you take more than one and eradicate any anomalies. That way, when your sensor sits at the end of a length of cable, you can eliminate lightning strikes and the odd Redneck trying to weld his pickup truck in near proximity.

    Well, the way I achieve that is to take say 16 ADC readings, sort them in sequential order of value, junk the top and bottom four readings as being 'out-of-range', sum and average the middle eight... this makes ADC readings in industrial applications pretty much bomb-proof...

    Now, whilst there's quite a few tricks and treats within this, here's a simple sort routine for doing just that (when you analyse it, it's pretty similar to your example Trent albeit a little more compact)... The Data to be sorted sits in an array called RawData, and when it falls out of the subroutine, RawData is in sequential order. Change DataA and RawData variables to WORDS if you need them. Those that know will notice that the additional variable DataA is only needed because PBP's SWAP command doesn't work with arrays.

    Code:
        CounterA var Byte
    DataA var Byte
    RawData var Byte [16]
    .. ..

        '
        '    Sort Array
        '    ----------
SortArray:
    CounterA=0
SortLoop:
    If RawData(CounterA+1) < RawData(CounterA) then
        DataA=RawData(CounterA)
        RawData(CounterA)=RawData(CounterA+1)
        RawData(CounterA+1+0)=DataA
        If CounterA > 0 then CounterA=CounterA-2
        endif
    CounterA=CounterA+1
    If CounterA < 15 then goto SortLoop
    Return
    And a version/test by Darrel:
    Code:
    ;Initialize your hardware first

A      VAR WORD
B      VAR WORD
TempA  VAR WORD
TempB  VAR WORD

LCDOUT $FE,1

For A = 0 to 65535
    LCDOUT $FE,2,"A=",DEC A
    For B = 0 to 65535
        TempA = A
        TempB = B
        TempA = TempA ^ TempB
        TempB = TempA ^ TempB
        TempA = TempA ^ TempB
        IF (TempA <> B) OR (TempB <> A) THEN ; Test Failed
            LCDOUT $FE,1,"Test Failed",$FE,$C0,"A=",DEC A,", B =",DEC B
            STOP
        ENDIF
    Next B
Next A

LCDOUT $FE,1,"Test Passed!"
STOP
    Then some 40 hours later (@ 20Mhz) [that's over 4 billion combinations],
    you would no doubt see the message "Test Passed!" on the LCD.

    Only a half hour into it, but it's still passing. Kinda obvious what the result will be.

    Update: 43hrs, Test Passed! (obviously)
    This article was originally published in forum thread: Number Sort Algorithm started by T.Jackson View original post