lean2/src/util/bit_tricks.cpp

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/*
Copyright (c) 2013 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura
*/
namespace lean {
unsigned log2(unsigned v) {
unsigned r = 0;
if (v & 0xFFFF0000) {
v >>= 16;
r |= 16;
}
if (v & 0xFF00) {
v >>= 8;
r |= 8;
}
if (v & 0xF0) {
v >>= 4;
r |= 4;
}
if (v & 0xC) {
v >>= 2;
r |= 2;
}
if (v & 0x2) {
v >>= 1;
r |= 1;
}
return r;
}
}