40 lines
695 B
C++
40 lines
695 B
C++
/*
|
|
Copyright (c) 2013 Microsoft Corporation. All rights reserved.
|
|
Released under Apache 2.0 license as described in the file LICENSE.
|
|
|
|
Author: Leonardo de Moura
|
|
*/
|
|
#include "runtime/debug.h"
|
|
|
|
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;
|
|
}
|
|
|
|
// make sure no one calls the math.h log2 accidentally
|
|
double log2(int v) {
|
|
(void)v;
|
|
lean_unreachable();
|
|
}
|
|
}
|