Finding MSB in bit string

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1 total messages Started by Tom Cunningham Wed, 05 Nov 1986 22:44

#9728

Author: Tom Cunningham
Date: Wed, 05 Nov 1986 22:44

26 lines
1167 bytes

Hopefully this won't get ignored after my last admittedly dumb posting
(re: conversion in printf; thanks for the *civil* replies).  I want to
find the MSB in a bit string without having to do a series of shifts.
Only the single bit in place needs to be isolated, to be used for example
in a powers-of-2 switch.  Finding the LSB in this way is no problem:

	unsigned i, t;

	t = -i;
	i &= t;
	switch (i) {
	case 1:
	case 2:
	case 4:
	case 8:
		.
		.
		.
	}

Any equivalent way to do this to get the MSB?

Tom Cunningham     "Good, fast, cheap -- select two."
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