blob: 391d49ba244dcf4e28b21083e7949de20f0df79e [file] [log] [blame]
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef NET_BASE_INT128_H_
#define NET_BASE_INT128_H_
#include <iosfwd>
#include "base/basictypes.h"
#include "net/base/net_export.h"
struct uint128_pod;
// An unsigned 128-bit integer type. Thread-compatible.
class uint128 {
public:
uint128(); // Sets to 0, but don't trust on this behavior.
uint128(uint64 top, uint64 bottom);
uint128(int bottom);
uint128(uint32 bottom); // Top 96 bits = 0
uint128(uint64 bottom); // hi_ = 0
uint128(const uint128 &val);
uint128(const uint128_pod &val);
void Initialize(uint64 top, uint64 bottom);
uint128& operator=(const uint128& b);
// Arithmetic operators.
// TODO: division, etc.
uint128& operator+=(const uint128& b);
uint128& operator-=(const uint128& b);
uint128& operator*=(const uint128& b);
uint128 operator++(int);
uint128 operator--(int);
uint128& operator<<=(int);
uint128& operator>>=(int);
uint128& operator&=(const uint128& b);
uint128& operator|=(const uint128& b);
uint128& operator^=(const uint128& b);
uint128& operator++();
uint128& operator--();
friend uint64 Uint128Low64(const uint128& v);
friend uint64 Uint128High64(const uint128& v);
// We add "std::" to avoid including all of port.h.
friend NET_EXPORT_PRIVATE std::ostream& operator<<(std::ostream& o,
const uint128& b);
private:
// Little-endian memory order optimizations can benefit from
// having lo_ first, hi_ last.
// See util/endian/endian.h and Load128/Store128 for storing a uint128.
uint64 lo_;
uint64 hi_;
// Not implemented, just declared for catching automatic type conversions.
uint128(uint8);
uint128(uint16);
uint128(float v);
uint128(double v);
};
// This is a POD form of uint128 which can be used for static variables which
// need to be operated on as uint128.
struct uint128_pod {
// Note: The ordering of fields is different than 'class uint128' but the
// same as its 2-arg constructor. This enables more obvious initialization
// of static instances, which is the primary reason for this struct in the
// first place. This does not seem to defeat any optimizations wrt
// operations involving this struct.
uint64 hi;
uint64 lo;
};
NET_EXPORT_PRIVATE extern const uint128_pod kuint128max;
// allow uint128 to be logged
NET_EXPORT_PRIVATE extern std::ostream& operator<<(std::ostream& o,
const uint128& b);
// Methods to access low and high pieces of 128-bit value.
// Defined externally from uint128 to facilitate conversion
// to native 128-bit types when compilers support them.
inline uint64 Uint128Low64(const uint128& v) { return v.lo_; }
inline uint64 Uint128High64(const uint128& v) { return v.hi_; }
// TODO: perhaps it would be nice to have int128, a signed 128-bit type?
// --------------------------------------------------------------------------
// Implementation details follow
// --------------------------------------------------------------------------
inline bool operator==(const uint128& lhs, const uint128& rhs) {
return (Uint128Low64(lhs) == Uint128Low64(rhs) &&
Uint128High64(lhs) == Uint128High64(rhs));
}
inline bool operator!=(const uint128& lhs, const uint128& rhs) {
return !(lhs == rhs);
}
inline uint128& uint128::operator=(const uint128& b) {
lo_ = b.lo_;
hi_ = b.hi_;
return *this;
}
inline uint128::uint128(): lo_(0), hi_(0) { }
inline uint128::uint128(uint64 top, uint64 bottom) : lo_(bottom), hi_(top) { }
inline uint128::uint128(const uint128 &v) : lo_(v.lo_), hi_(v.hi_) { }
inline uint128::uint128(const uint128_pod &v) : lo_(v.lo), hi_(v.hi) { }
inline uint128::uint128(uint64 bottom) : lo_(bottom), hi_(0) { }
inline uint128::uint128(uint32 bottom) : lo_(bottom), hi_(0) { }
inline uint128::uint128(int bottom)
: lo_(static_cast<uint32>(bottom)), hi_(0) {
if (bottom < 0) {
--hi_;
}
}
inline void uint128::Initialize(uint64 top, uint64 bottom) {
hi_ = top;
lo_ = bottom;
}
// Comparison operators.
#define CMP128(op) \
inline bool operator op(const uint128& lhs, const uint128& rhs) { \
return (Uint128High64(lhs) == Uint128High64(rhs)) ? \
(Uint128Low64(lhs) op Uint128Low64(rhs)) : \
(Uint128High64(lhs) op Uint128High64(rhs)); \
}
CMP128(<)
CMP128(>)
CMP128(>=)
CMP128(<=)
#undef CMP128
// Unary operators
inline uint128 operator-(const uint128& val) {
const uint64 hi_flip = ~Uint128High64(val);
const uint64 lo_flip = ~Uint128Low64(val);
const uint64 lo_add = lo_flip + 1;
if (lo_add < lo_flip) {
return uint128(hi_flip + 1, lo_add);
}
return uint128(hi_flip, lo_add);
}
inline bool operator!(const uint128& val) {
return !Uint128High64(val) && !Uint128Low64(val);
}
// Logical operators.
inline uint128 operator~(const uint128& val) {
return uint128(~Uint128High64(val), ~Uint128Low64(val));
}
#define LOGIC128(op) \
inline uint128 operator op(const uint128& lhs, const uint128& rhs) { \
return uint128(Uint128High64(lhs) op Uint128High64(rhs), \
Uint128Low64(lhs) op Uint128Low64(rhs)); \
}
LOGIC128(|)
LOGIC128(&)
LOGIC128(^)
#undef LOGIC128
#define LOGICASSIGN128(op) \
inline uint128& uint128::operator op(const uint128& other) { \
hi_ op other.hi_; \
lo_ op other.lo_; \
return *this; \
}
LOGICASSIGN128(|=)
LOGICASSIGN128(&=)
LOGICASSIGN128(^=)
#undef LOGICASSIGN128
// Shift operators.
inline uint128 operator<<(const uint128& val, int amount) {
// uint64 shifts of >= 64 are undefined, so we will need some special-casing.
if (amount < 64) {
if (amount == 0) {
return val;
}
uint64 new_hi = (Uint128High64(val) << amount) |
(Uint128Low64(val) >> (64 - amount));
uint64 new_lo = Uint128Low64(val) << amount;
return uint128(new_hi, new_lo);
} else if (amount < 128) {
return uint128(Uint128Low64(val) << (amount - 64), 0);
} else {
return uint128(0, 0);
}
}
inline uint128 operator>>(const uint128& val, int amount) {
// uint64 shifts of >= 64 are undefined, so we will need some special-casing.
if (amount < 64) {
if (amount == 0) {
return val;
}
uint64 new_hi = Uint128High64(val) >> amount;
uint64 new_lo = (Uint128Low64(val) >> amount) |
(Uint128High64(val) << (64 - amount));
return uint128(new_hi, new_lo);
} else if (amount < 128) {
return uint128(0, Uint128High64(val) >> (amount - 64));
} else {
return uint128(0, 0);
}
}
inline uint128& uint128::operator<<=(int amount) {
// uint64 shifts of >= 64 are undefined, so we will need some special-casing.
if (amount < 64) {
if (amount != 0) {
hi_ = (hi_ << amount) | (lo_ >> (64 - amount));
lo_ = lo_ << amount;
}
} else if (amount < 128) {
hi_ = lo_ << (amount - 64);
lo_ = 0;
} else {
hi_ = 0;
lo_ = 0;
}
return *this;
}
inline uint128& uint128::operator>>=(int amount) {
// uint64 shifts of >= 64 are undefined, so we will need some special-casing.
if (amount < 64) {
if (amount != 0) {
lo_ = (lo_ >> amount) | (hi_ << (64 - amount));
hi_ = hi_ >> amount;
}
} else if (amount < 128) {
hi_ = 0;
lo_ = hi_ >> (amount - 64);
} else {
hi_ = 0;
lo_ = 0;
}
return *this;
}
inline uint128 operator+(const uint128& lhs, const uint128& rhs) {
return uint128(lhs) += rhs;
}
inline uint128 operator-(const uint128& lhs, const uint128& rhs) {
return uint128(lhs) -= rhs;
}
inline uint128 operator*(const uint128& lhs, const uint128& rhs) {
return uint128(lhs) *= rhs;
}
inline uint128& uint128::operator+=(const uint128& b) {
hi_ += b.hi_;
uint64 lolo = lo_ + b.lo_;
if (lolo < lo_)
++hi_;
lo_ = lolo;
return *this;
}
inline uint128& uint128::operator-=(const uint128& b) {
hi_ -= b.hi_;
if (b.lo_ > lo_)
--hi_;
lo_ -= b.lo_;
return *this;
}
inline uint128& uint128::operator*=(const uint128& b) {
uint64 a96 = hi_ >> 32;
uint64 a64 = hi_ & 0xffffffffu;
uint64 a32 = lo_ >> 32;
uint64 a00 = lo_ & 0xffffffffu;
uint64 b96 = b.hi_ >> 32;
uint64 b64 = b.hi_ & 0xffffffffu;
uint64 b32 = b.lo_ >> 32;
uint64 b00 = b.lo_ & 0xffffffffu;
// multiply [a96 .. a00] x [b96 .. b00]
// terms higher than c96 disappear off the high side
// terms c96 and c64 are safe to ignore carry bit
uint64 c96 = a96 * b00 + a64 * b32 + a32 * b64 + a00 * b96;
uint64 c64 = a64 * b00 + a32 * b32 + a00 * b64;
this->hi_ = (c96 << 32) + c64;
this->lo_ = 0;
// add terms after this one at a time to capture carry
*this += uint128(a32 * b00) << 32;
*this += uint128(a00 * b32) << 32;
*this += a00 * b00;
return *this;
}
inline uint128 uint128::operator++(int) {
uint128 tmp(*this);
*this += 1;
return tmp;
}
inline uint128 uint128::operator--(int) {
uint128 tmp(*this);
*this -= 1;
return tmp;
}
inline uint128& uint128::operator++() {
*this += 1;
return *this;
}
inline uint128& uint128::operator--() {
*this -= 1;
return *this;
}
#endif // NET_BASE_INT128_H_