47 lines
2.4 KiB
Markdown
47 lines
2.4 KiB
Markdown
uint128
|
|
-------
|
|
|
|
[](https://godoc.org/github.com/lukechampine/uint128)
|
|
[](https://goreportcard.com/report/github.com/lukechampine/uint128)
|
|
|
|
```
|
|
go get lukechampine.com/uint128
|
|
```
|
|
|
|
`uint128` provides a high-performance `Uint128` type that supports standard arithmetic
|
|
operations. Unlike `math/big`, operations on `Uint128` values always produce new values
|
|
instead of modifying a pointer receiver. A `Uint128` value is therefore immutable, just
|
|
like `uint64` and friends.
|
|
|
|
The name `uint128.Uint128` stutters, so I recommend either using a "dot import"
|
|
or aliasing `uint128.Uint128` to give it a project-specific name. Embedding the type
|
|
is not recommended, because methods will still return `uint128.Uint128`; this means that,
|
|
if you want to extend the type with new methods, your best bet is probably to copy the
|
|
source code wholesale and rename the identifier. ¯\\\_(ツ)\_/¯
|
|
|
|
|
|
# Benchmarks
|
|
|
|
Addition, multiplication, and subtraction are on par with their native 64-bit
|
|
equivalents. Division is slower: ~20x slower when dividing a `Uint128` by a
|
|
`uint64`, and ~100x slower when dividing by a `Uint128`. However, division is
|
|
still faster than with `big.Int` (for the same operands), especially when
|
|
dividing by a `uint64`.
|
|
|
|
```
|
|
BenchmarkArithmetic/Add-4 2000000000 0.45 ns/op 0 B/op 0 allocs/op
|
|
BenchmarkArithmetic/Sub-4 2000000000 0.67 ns/op 0 B/op 0 allocs/op
|
|
BenchmarkArithmetic/Mul-4 2000000000 0.42 ns/op 0 B/op 0 allocs/op
|
|
BenchmarkArithmetic/Lsh-4 2000000000 1.06 ns/op 0 B/op 0 allocs/op
|
|
BenchmarkArithmetic/Rsh-4 2000000000 1.06 ns/op 0 B/op 0 allocs/op
|
|
|
|
BenchmarkDivision/native_64/64-4 2000000000 0.39 ns/op 0 B/op 0 allocs/op
|
|
BenchmarkDivision/Div_128/64-4 2000000000 6.28 ns/op 0 B/op 0 allocs/op
|
|
BenchmarkDivision/Div_128/128-4 30000000 45.2 ns/op 0 B/op 0 allocs/op
|
|
BenchmarkDivision/big.Int_128/64-4 20000000 98.2 ns/op 8 B/op 1 allocs/op
|
|
BenchmarkDivision/big.Int_128/128-4 30000000 53.4 ns/op 48 B/op 1 allocs/op
|
|
|
|
BenchmarkString/Uint128-4 10000000 173 ns/op 48 B/op 1 allocs/op
|
|
BenchmarkString/big.Int-4 5000000 350 ns/op 144 B/op 3 allocs/op
|
|
```
|