If I have a bit mask (i.e. a decimal conversion of a binary number) and I want to find the ...
Ah, I think I've got it
Thanks!
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| Bitwise conversions http://www.x404.co.uk/forum/viewtopic.php?f=4&t=16202 |
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| Author: | Fogmeister [ Tue Apr 03, 2012 10:34 pm ] |
| Post subject: | Bitwise conversions |
If I have a bit mask (i.e. a decimal conversion of a binary number) and I want to find the ... Ah, I think I've got it Thanks!
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| Author: | Fogmeister [ Wed Apr 04, 2012 1:58 pm ] |
| Post subject: | Re: Bitwise conversions |
OK, got a question now It is bitwise operator related but be thinking about sudoku to put it in context. I will be comparing three cells. Cell a will have the definite number 7 in it (for example). Cell b will have the definite number 5 in it. Cell c will have the candidate numbers 1, 3, 5 and 7 in it. They can all "see" each other (i.e. in the same box, row or column). At the moment my loop runs and I end up so that... Cell a = 7 Cell b = 5 Cell c = 1,3 (i.e. it has had 5 and 7 eliminated) BTW (7 is actually 64 and 1,3 is actually 5 (bitwise)). That's all very good and VERY quick but at the end I want to see what has been removed. If I take a copy at the beginning so I have ... origCell a = 7 origCell b = 5 origCell c = 1,3,5,7 How can I compare cell c and origCell c to see what has been eliminated? cell c = 1,3 = 5 = 000000101 origCell c = 1,3,5,7 = 85 = 001010101 Ah, XOR! cell c XOR origCell c = 001010000 = 80 Is that right? |
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| Author: | Fogmeister [ Wed Apr 04, 2012 2:15 pm ] | |||||||||
| Post subject: | Re: Bitwise conversions | |||||||||
Ah, I can then get the individual bits using a shift operator.
This lists all the numbers (bits) that were eliminated from the given cell. |
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