uint128.h 文件参考

Portable 128-bit unsigned integer with native-fastpath multiplication. 更多...

#include <cstdint>
#include <iostream>
#include <type_traits>
#include <utility>
#include "./macros.h"

uint128.h 的引用(Include)关系图:

浏览源代码.

类
class	vlink::Uint128
	128-bit unsigned integer represented as two 64-bit halves with full operator support. 更多...
struct	std::hash< vlink::Uint128 >
	std::hash specialisation enabling vlink::Uint128 keys in unordered containers. 更多...

命名空间
	vlink

类型定义
using	vlink::uint128_t = Uint128
	Convenience alias matching the lowercase fixed-width style of the standard integer types. 更多...

详细描述

Portable 128-bit unsigned integer with native-fastpath multiplication.

vlink::Uint128 stores the value as a pair of uint64_t halves (high_, low_). On GCC and Clang 64-bit targets the multiplication, division and modulo paths delegate to the compiler-native __uint128_t for maximum performance; on platforms without that builtin the portable fallback (mul_u128_fallback / u128_divmod) is used.

Supported operator set:

Category	Operators	Notes
Arithmetic	+ - * / % += -= *= /= %=	Division throws on divisor 0
Bitwise	OR AND XOR NOT shift compound-assign	Shifts clamp to [0, 128]
Comparison	== != < > <= >=	Lexicographic over (high, low)
Increment	++ – (prefix and postfix)	Carry/borrow crosses the 64-bit line
Stream	operator<<(std::ostream&)	Uppercase hexadecimal output

Implicit construction from integral types

The single-argument constructor is intentionally non-explicit so integral literals can flow into Uint128 transparently. Signed source values are sign-extended, unsigned values are zero-extended, and __uint128_t source values are split into halves.

Conversion back to __uint128_t

An explicit operator __uint128_t() is provided on platforms that expose the type.

std::hash specialisation

A std::hash<vlink::Uint128> specialisation at the bottom of this file enables use inside std::unordered_map and std::unordered_set.

Example

vlink::Uint128 a(0, UINT64_MAX);
vlink::Uint128 b(1, 0);
vlink::Uint128 c = a + vlink::Uint128(0, 1);
assert(c == b);
 
std::unordered_map<vlink::uint128_t, std::string> map;
map[vlink::Uint128(0xDEAD, 0xBEEF)] = "key";