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Unread 04-10-2005, 20:40
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Re: 16 bit math on PIC

Quote:
Originally Posted by Dave Flowerday
I believe all this is saying is that f (which is specifying a register number) can't be greater than 127, since that PIC only has 128 registers. The contents of the register can be larger than that, however.
I think that the contents are limited to 127. If you look at some of the other instructions, they say 0<f<255. I'm pretty sure it has something to do with signed vs unsigned contents, but I don't know what happens if the instruction causes it to overflow. Various websites mention this 127 limit when it comes to the incf/decf type instructions (ie, if you increment 127, it rolls over to 0). But nobody talks about what happens with the arithmatic operations.
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