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/*
* Copyright 2016 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
*/
#include <intrin.h>
//
//
//
#include "util.h"
//
//
//
bool
is_pow2_u32(uint32_t n)
{
return (n & (n-1)) == 0;
}
//
//
//
uint32_t
pow2_ru_u32(uint32_t n)
{
n--;
n |= n >> 1;
n |= n >> 2;
n |= n >> 4;
n |= n >> 8;
n |= n >> 16;
n++;
return n;
}
//
//
//
uint32_t
pow2_rd_u32(uint32_t n)
{
return 1u << msb_idx_u32(n);
}
//
// ASSUMES NON-ZERO
//
uint32_t
msb_idx_u32(uint32_t n)
{
#ifdef _MSC_VER
uint32_t index;
_BitScanReverse((unsigned long *)&index,n);
return index;
#elif defined(__GNUC__)
#error "BUSTED msb_index()"
return 31 - __builtin_clz(mask);
#else
#error "No msb_index()"
#endif
}
//
//
//
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