Signal Filtering
Posted by anonymous 16 months ago
Snapping
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6 x 3Description
Green input = "data"
Red input = "selector"
Intermediate red wire: subtracts 2^31 from "data" values which are in the "selector". The max value of a signed 32-bit int is 2^31 - 1 so any positive number minus 2^31 is negative.
Last combinator extracts negatives and subtracts 2^31 again, which cancels out the first subtraction: input x becomes (x - 2^31) in red then (x - 2^31 - 2^31) in output which equals x because of 32-bit integer arithmetic.
Adding / subtracting 2^31 FLIPS the int "sign bit"
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