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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.
| *
| */
|
| #ifdef _MSC_VER
|
| #include <intrin.h>
|
| #else
|
|
|
| #endif
|
| //
| //
| //
|
| #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)
| {
| #if defined( _MSC_VER )
|
| uint32_t index;
|
| _BitScanReverse((unsigned long *)&index,n);
|
| return index;
|
| #elif defined( __GNUC__ )
|
| return __builtin_clz(n) ^ 31;
|
| #else
|
| #error "No msb_index()"
|
| #endif
| }
|
| //
| //
| //
|
|
