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// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
* Ceph - scalable distributed file system
*
* Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
*
* This is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License version 2.1, as published by the Free Software
* Foundation. See file COPYING.
*
*/
#ifndef CEPH_INTARITH_H
#define CEPH_INTARITH_H
#include <type_traits>
template<typename T, typename U>
constexpr inline std::make_unsigned_t<std::common_type_t<T, U>> div_round_up(T n, U d) {
return (n + d - 1) / d;
}
template<typename T, typename U>
constexpr inline std::make_unsigned_t<std::common_type_t<T, U>> round_up_to(T n, U d) {
return (n % d ? (n + d - n % d) : n);
}
template<typename T, typename U>
constexpr inline std::make_unsigned_t<std::common_type_t<T, U>> shift_round_up(T x, U y) {
return (x + (1 << y) - 1) >> y;
}
/*
* Wrapper to determine if value is a power of 2
*/
template<typename T>
constexpr inline bool isp2(T x) {
return (x & (x - 1)) == 0;
}
/*
* Wrappers for various sorts of alignment and rounding. The "align" must
* be a power of 2. Often times it is a block, sector, or page.
*/
/*
* return x rounded down to an align boundary
* eg, p2align(1200, 1024) == 1024 (1*align)
* eg, p2align(1024, 1024) == 1024 (1*align)
* eg, p2align(0x1234, 0x100) == 0x1200 (0x12*align)
* eg, p2align(0x5600, 0x100) == 0x5600 (0x56*align)
*/
template<typename T>
constexpr inline T p2align(T x, T align) {
return x & -align;
}
/*
* return x % (mod) align
* eg, p2phase(0x1234, 0x100) == 0x34 (x-0x12*align)
* eg, p2phase(0x5600, 0x100) == 0x00 (x-0x56*align)
*/
template<typename T>
constexpr inline T p2phase(T x, T align) {
return x & (align - 1);
}
/*
* return how much space is left in this block (but if it's perfectly
* aligned, return 0).
* eg, p2nphase(0x1234, 0x100) == 0xcc (0x13*align-x)
* eg, p2nphase(0x5600, 0x100) == 0x00 (0x56*align-x)
*/
template<typename T>
constexpr inline T p2nphase(T x, T align) {
return -x & (align - 1);
}
/*
* return x rounded up to an align boundary
* eg, p2roundup(0x1234, 0x100) == 0x1300 (0x13*align)
* eg, p2roundup(0x5600, 0x100) == 0x5600 (0x56*align)
*/
template<typename T>
constexpr inline T p2roundup(T x, T align) {
return -(-x & -align);
}
// count trailing zeros.
// NOTE: the builtin is nondeterministic on 0 input
template<class T>
inline typename std::enable_if<
(std::is_integral<T>::value &&
sizeof(T) <= sizeof(unsigned)),
unsigned>::type ctz(T v) {
if (v == 0)
return sizeof(v) * 8;
return __builtin_ctz(v);
}
template<class T>
inline typename std::enable_if<
(std::is_integral<T>::value &&
sizeof(T) > sizeof(unsigned int) &&
sizeof(T) <= sizeof(unsigned long)),
unsigned>::type ctz(T v) {
if (v == 0)
return sizeof(v) * 8;
return __builtin_ctzl(v);
}
template<class T>
inline typename std::enable_if<
(std::is_integral<T>::value &&
sizeof(T) > sizeof(unsigned long) &&
sizeof(T) <= sizeof(unsigned long long)),
unsigned>::type ctz(T v) {
if (v == 0)
return sizeof(v) * 8;
return __builtin_ctzll(v);
}
// count leading zeros
// NOTE: the builtin is nondeterministic on 0 input
template<class T>
inline typename std::enable_if<
(std::is_integral<T>::value &&
sizeof(T) <= sizeof(unsigned)),
unsigned>::type clz(T v) {
if (v == 0)
return sizeof(v) * 8;
return __builtin_clz(v);
}
template<class T>
inline typename std::enable_if<
(std::is_integral<T>::value &&
sizeof(T) > sizeof(unsigned int) &&
sizeof(T) <= sizeof(unsigned long)),
unsigned>::type clz(T v) {
if (v == 0)
return sizeof(v) * 8;
return __builtin_clzl(v);
}
template<class T>
inline typename std::enable_if<
(std::is_integral<T>::value &&
sizeof(T) > sizeof(unsigned long) &&
sizeof(T) <= sizeof(unsigned long long)),
unsigned>::type clz(T v) {
if (v == 0)
return sizeof(v) * 8;
return __builtin_clzll(v);
}
// count bits (set + any 0's that follow)
template<class T>
inline typename std::enable_if<
(std::is_integral<T>::value &&
sizeof(T) <= sizeof(unsigned)),
unsigned>::type cbits(T v) {
if (v == 0)
return 0;
return (sizeof(v) * 8) - __builtin_clz(v);
}
template<class T>
inline typename std::enable_if<
(std::is_integral<T>::value &&
sizeof(T) > sizeof(unsigned int) &&
sizeof(T) <= sizeof(unsigned long)),
unsigned>::type cbits(T v) {
if (v == 0)
return 0;
return (sizeof(v) * 8) - __builtin_clzl(v);
}
template<class T>
inline typename std::enable_if<
(std::is_integral<T>::value &&
sizeof(T) > sizeof(unsigned long) &&
sizeof(T) <= sizeof(unsigned long long)),
unsigned>::type cbits(T v) {
if (v == 0)
return 0;
return (sizeof(v) * 8) - __builtin_clzll(v);
}
#endif
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