Kenny Baby wrote:
>
> I am trying to write a bcd down counter. If i have a hex value of
> 0x81 and then decrement the file with 'decf file,f' the new value
> will be 0x80, if i dec again i will get 0x7f. I thought that the dc
> flag would be set when going from 0x80 to 0x7f. It doe's'nt appear to
> in mpasm using a pic18c84. Is'nt the dc flag a carry/borrow. whis is
> set when going up from 0x0f-0x10 and down from 0x80-0x7f. The data
> sheets say the the dc flag is effected by 'decf file' inst.

The incf and decf instructions affect Z only. If you want a digit
carry bit (DC) on an increment or decrement, you have to add or
substract the literal value one.
Remember the DC bit is reversed when used as a borrow flag.

--
Friendly Regards

Tjaart van der Walt
mailto:tjaart@wasp.co.za
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