Version: v0.0.0-...-8a52383 Latest Latest Go to latest
Published: Jan 31, 2019 License: BSD-3-Clause

## Documentation ¶

### Overview ¶

Package bits implements bit counting and manipulation functions for the predeclared unsigned integer types.

### Constants ¶

View Source
`const UintSize = uintSize`

UintSize is the size of a uint in bits.

### Variables ¶

This section is empty.

### Functions ¶

`func Add(x, y, carry uint) (sum, carryOut uint)`

Add returns the sum with carry of x, y and carry: sum = x + y + carry. The carry input must be 0 or 1; otherwise the behavior is undefined. The carryOut output is guaranteed to be 0 or 1.

`func Add32(x, y, carry uint32) (sum, carryOut uint32)`

Add32 returns the sum with carry of x, y and carry: sum = x + y + carry. The carry input must be 0 or 1; otherwise the behavior is undefined. The carryOut output is guaranteed to be 0 or 1.

`func Add64(x, y, carry uint64) (sum, carryOut uint64)`

Add64 returns the sum with carry of x, y and carry: sum = x + y + carry. The carry input must be 0 or 1; otherwise the behavior is undefined. The carryOut output is guaranteed to be 0 or 1.

#### func Div ¶

`func Div(hi, lo, y uint) (quo, rem uint)`

Div returns the quotient and remainder of (hi, lo) divided by y: quo = (hi, lo)/y, rem = (hi, lo)%y with the dividend bits' upper half in parameter hi and the lower half in parameter lo. Div panics for y == 0 (division by zero) or y <= hi (quotient overflow).

#### func Div32 ¶

`func Div32(hi, lo, y uint32) (quo, rem uint32)`

Div32 returns the quotient and remainder of (hi, lo) divided by y: quo = (hi, lo)/y, rem = (hi, lo)%y with the dividend bits' upper half in parameter hi and the lower half in parameter lo. Div32 panics for y == 0 (division by zero) or y <= hi (quotient overflow).

#### func Div64 ¶

`func Div64(hi, lo, y uint64) (quo, rem uint64)`

Div64 returns the quotient and remainder of (hi, lo) divided by y: quo = (hi, lo)/y, rem = (hi, lo)%y with the dividend bits' upper half in parameter hi and the lower half in parameter lo. Div64 panics for y == 0 (division by zero) or y <= hi (quotient overflow).

`func LeadingZeros(x uint) int`

LeadingZeros returns the number of leading zero bits in x; the result is UintSize for x == 0.

`func LeadingZeros16(x uint16) int`

LeadingZeros16 returns the number of leading zero bits in x; the result is 16 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
}
```
```Output:

```

`func LeadingZeros32(x uint32) int`

LeadingZeros32 returns the number of leading zero bits in x; the result is 32 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
}
```
```Output:

```

`func LeadingZeros64(x uint64) int`

LeadingZeros64 returns the number of leading zero bits in x; the result is 64 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
}
```
```Output:

```

`func LeadingZeros8(x uint8) int`

LeadingZeros8 returns the number of leading zero bits in x; the result is 8 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
}
```
```Output:

```

#### func Len ¶

`func Len(x uint) int`

Len returns the minimum number of bits required to represent x; the result is 0 for x == 0.

#### func Len16 ¶

`func Len16(x uint16) (n int)`

Len16 returns the minimum number of bits required to represent x; the result is 0 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("Len16(%016b) = %d\n", 8, bits.Len16(8))
}
```
```Output:

Len16(0000000000001000) = 4
```

#### func Len32 ¶

`func Len32(x uint32) (n int)`

Len32 returns the minimum number of bits required to represent x; the result is 0 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("Len32(%032b) = %d\n", 8, bits.Len32(8))
}
```
```Output:

Len32(00000000000000000000000000001000) = 4
```

#### func Len64 ¶

`func Len64(x uint64) (n int)`

Len64 returns the minimum number of bits required to represent x; the result is 0 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("Len64(%064b) = %d\n", 8, bits.Len64(8))
}
```
```Output:

Len64(0000000000000000000000000000000000000000000000000000000000001000) = 4
```

#### func Len8 ¶

`func Len8(x uint8) int`

Len8 returns the minimum number of bits required to represent x; the result is 0 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("Len8(%08b) = %d\n", 8, bits.Len8(8))
}
```
```Output:

Len8(00001000) = 4
```

#### func Mul ¶

`func Mul(x, y uint) (hi, lo uint)`

Mul returns the full-width product of x and y: (hi, lo) = x * y with the product bits' upper half returned in hi and the lower half returned in lo.

#### func Mul32 ¶

`func Mul32(x, y uint32) (hi, lo uint32)`

Mul32 returns the 64-bit product of x and y: (hi, lo) = x * y with the product bits' upper half returned in hi and the lower half returned in lo.

#### func Mul64 ¶

`func Mul64(x, y uint64) (hi, lo uint64)`

Mul64 returns the 128-bit product of x and y: (hi, lo) = x * y with the product bits' upper half returned in hi and the lower half returned in lo.

#### func OnesCount ¶

`func OnesCount(x uint) int`

OnesCount returns the number of one bits ("population count") in x.

#### func OnesCount16 ¶

`func OnesCount16(x uint16) int`

OnesCount16 returns the number of one bits ("population count") in x.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("OnesCount16(%016b) = %d\n", 14, bits.OnesCount16(14))
}
```
```Output:

OnesCount16(0000000000001110) = 3
```

#### func OnesCount32 ¶

`func OnesCount32(x uint32) int`

OnesCount32 returns the number of one bits ("population count") in x.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("OnesCount32(%032b) = %d\n", 14, bits.OnesCount32(14))
}
```
```Output:

OnesCount32(00000000000000000000000000001110) = 3
```

#### func OnesCount64 ¶

`func OnesCount64(x uint64) int`

OnesCount64 returns the number of one bits ("population count") in x.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("OnesCount64(%064b) = %d\n", 14, bits.OnesCount64(14))
}
```
```Output:

OnesCount64(0000000000000000000000000000000000000000000000000000000000001110) = 3
```

#### func OnesCount8 ¶

`func OnesCount8(x uint8) int`

OnesCount8 returns the number of one bits ("population count") in x.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("OnesCount8(%08b) = %d\n", 14, bits.OnesCount8(14))
}
```
```Output:

OnesCount8(00001110) = 3
```

#### func Reverse ¶

`func Reverse(x uint) uint`

Reverse returns the value of x with its bits in reversed order.

#### func Reverse16 ¶

`func Reverse16(x uint16) uint16`

Reverse16 returns the value of x with its bits in reversed order.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%016b\n", 19)
fmt.Printf("%016b\n", bits.Reverse16(19))
}
```
```Output:

0000000000010011
1100100000000000
```

#### func Reverse32 ¶

`func Reverse32(x uint32) uint32`

Reverse32 returns the value of x with its bits in reversed order.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%032b\n", 19)
fmt.Printf("%032b\n", bits.Reverse32(19))
}
```
```Output:

00000000000000000000000000010011
11001000000000000000000000000000
```

#### func Reverse64 ¶

`func Reverse64(x uint64) uint64`

Reverse64 returns the value of x with its bits in reversed order.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%064b\n", 19)
fmt.Printf("%064b\n", bits.Reverse64(19))
}
```
```Output:

0000000000000000000000000000000000000000000000000000000000010011
1100100000000000000000000000000000000000000000000000000000000000
```

#### func Reverse8 ¶

`func Reverse8(x uint8) uint8`

Reverse8 returns the value of x with its bits in reversed order.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%08b\n", 19)
fmt.Printf("%08b\n", bits.Reverse8(19))
}
```
```Output:

00010011
11001000
```

#### func ReverseBytes ¶

`func ReverseBytes(x uint) uint`

ReverseBytes returns the value of x with its bytes in reversed order.

#### func ReverseBytes16 ¶

`func ReverseBytes16(x uint16) uint16`

ReverseBytes16 returns the value of x with its bytes in reversed order.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%016b\n", 15)
fmt.Printf("%016b\n", bits.ReverseBytes16(15))
}
```
```Output:

0000000000001111
0000111100000000
```

#### func ReverseBytes32 ¶

`func ReverseBytes32(x uint32) uint32`

ReverseBytes32 returns the value of x with its bytes in reversed order.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%032b\n", 15)
fmt.Printf("%032b\n", bits.ReverseBytes32(15))
}
```
```Output:

00000000000000000000000000001111
00001111000000000000000000000000
```

#### func ReverseBytes64 ¶

`func ReverseBytes64(x uint64) uint64`

ReverseBytes64 returns the value of x with its bytes in reversed order.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%064b\n", 15)
fmt.Printf("%064b\n", bits.ReverseBytes64(15))
}
```
```Output:

0000000000000000000000000000000000000000000000000000000000001111
0000111100000000000000000000000000000000000000000000000000000000
```

#### func RotateLeft ¶

`func RotateLeft(x uint, k int) uint`

RotateLeft returns the value of x rotated left by (k mod UintSize) bits. To rotate x right by k bits, call RotateLeft(x, -k).

#### func RotateLeft16 ¶

`func RotateLeft16(x uint16, k int) uint16`

RotateLeft16 returns the value of x rotated left by (k mod 16) bits. To rotate x right by k bits, call RotateLeft16(x, -k).

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%016b\n", 15)
fmt.Printf("%016b\n", bits.RotateLeft16(15, 2))
fmt.Printf("%016b\n", bits.RotateLeft16(15, -2))
}
```
```Output:

0000000000001111
0000000000111100
1100000000000011
```

#### func RotateLeft32 ¶

`func RotateLeft32(x uint32, k int) uint32`

RotateLeft32 returns the value of x rotated left by (k mod 32) bits. To rotate x right by k bits, call RotateLeft32(x, -k).

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%032b\n", 15)
fmt.Printf("%032b\n", bits.RotateLeft32(15, 2))
fmt.Printf("%032b\n", bits.RotateLeft32(15, -2))
}
```
```Output:

00000000000000000000000000001111
00000000000000000000000000111100
11000000000000000000000000000011
```

#### func RotateLeft64 ¶

`func RotateLeft64(x uint64, k int) uint64`

RotateLeft64 returns the value of x rotated left by (k mod 64) bits. To rotate x right by k bits, call RotateLeft64(x, -k).

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%064b\n", 15)
fmt.Printf("%064b\n", bits.RotateLeft64(15, 2))
fmt.Printf("%064b\n", bits.RotateLeft64(15, -2))
}
```
```Output:

0000000000000000000000000000000000000000000000000000000000001111
0000000000000000000000000000000000000000000000000000000000111100
1100000000000000000000000000000000000000000000000000000000000011
```

#### func RotateLeft8 ¶

`func RotateLeft8(x uint8, k int) uint8`

RotateLeft8 returns the value of x rotated left by (k mod 8) bits. To rotate x right by k bits, call RotateLeft8(x, -k).

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("%08b\n", 15)
fmt.Printf("%08b\n", bits.RotateLeft8(15, 2))
fmt.Printf("%08b\n", bits.RotateLeft8(15, -2))
}
```
```Output:

00001111
00111100
11000011
```

#### func Sub ¶

`func Sub(x, y, borrow uint) (diff, borrowOut uint)`

Sub returns the difference of x, y and borrow: diff = x - y - borrow. The borrow input must be 0 or 1; otherwise the behavior is undefined. The borrowOut output is guaranteed to be 0 or 1.

#### func Sub32 ¶

`func Sub32(x, y, borrow uint32) (diff, borrowOut uint32)`

Sub32 returns the difference of x, y and borrow, diff = x - y - borrow. The borrow input must be 0 or 1; otherwise the behavior is undefined. The borrowOut output is guaranteed to be 0 or 1.

#### func Sub64 ¶

`func Sub64(x, y, borrow uint64) (diff, borrowOut uint64)`

Sub64 returns the difference of x, y and borrow: diff = x - y - borrow. The borrow input must be 0 or 1; otherwise the behavior is undefined. The borrowOut output is guaranteed to be 0 or 1.

#### func TrailingZeros ¶

`func TrailingZeros(x uint) int`

TrailingZeros returns the number of trailing zero bits in x; the result is UintSize for x == 0.

#### func TrailingZeros16 ¶

`func TrailingZeros16(x uint16) int`

TrailingZeros16 returns the number of trailing zero bits in x; the result is 16 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("TrailingZeros16(%016b) = %d\n", 14, bits.TrailingZeros16(14))
}
```
```Output:

TrailingZeros16(0000000000001110) = 1
```

#### func TrailingZeros32 ¶

`func TrailingZeros32(x uint32) int`

TrailingZeros32 returns the number of trailing zero bits in x; the result is 32 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("TrailingZeros32(%032b) = %d\n", 14, bits.TrailingZeros32(14))
}
```
```Output:

TrailingZeros32(00000000000000000000000000001110) = 1
```

#### func TrailingZeros64 ¶

`func TrailingZeros64(x uint64) int`

TrailingZeros64 returns the number of trailing zero bits in x; the result is 64 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("TrailingZeros64(%064b) = %d\n", 14, bits.TrailingZeros64(14))
}
```
```Output:

TrailingZeros64(0000000000000000000000000000000000000000000000000000000000001110) = 1
```

#### func TrailingZeros8 ¶

`func TrailingZeros8(x uint8) int`

TrailingZeros8 returns the number of trailing zero bits in x; the result is 8 for x == 0.

Example
```package main

import (
"fmt"
"math/bits"
)

func main() {
fmt.Printf("TrailingZeros8(%08b) = %d\n", 14, bits.TrailingZeros8(14))
}
```
```Output:

TrailingZeros8(00001110) = 1
```

### Types ¶

This section is empty.