PIC Microcontoller Math Method

Two's complemnt of a 16 bit word (2 bytes)

        comf    var,f           ;Complement all bytes
        comf    var+1,f

        incf    var,f           ;Inc. low byte always
        skpnz                   ;Skip if no carry to higher bytes
        incf    var+1,f         ;Carry to next byte

Questions:

Shouldn't the skpnz be skpnc? Ken R Helberg of Altec Lansing replies: incf doesn't affect the carry flag, so skpnz is correct.+
+

Comments:

If I'm not mistaken, the three last lines could be replaced with

incfsz var,F
incf var+1,F+

Stef Says: " Increment of "var+1" must be done only if
incf var
result IS zero. So, incfsz will not work. " +

file: /Techref/microchip/math/neg/16bit.htm, 1KB, , updated: 2011/4/21 04:23, local time: 2025/4/30 04:01,

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PIC Microcontoller Math Method

Two's complemnt of a 16 bit word (2 bytes)

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