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Package bits

import "math/bits"
Overview
Index
Examples

Overview ▾

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

Index ▾

Constants
func Add(x, y, carry uint) (sum, carryOut uint)
func Add32(x, y, carry uint32) (sum, carryOut uint32)
func Add64(x, y, carry uint64) (sum, carryOut uint64)
func Div(hi, lo, y uint) (quo, rem uint)
func Div32(hi, lo, y uint32) (quo, rem uint32)
func Div64(hi, lo, y uint64) (quo, rem uint64)
func LeadingZeros(x uint) int
func LeadingZeros16(x uint16) int
func LeadingZeros32(x uint32) int
func LeadingZeros64(x uint64) int
func LeadingZeros8(x uint8) int
func Len(x uint) int
func Len16(x uint16) (n int)
func Len32(x uint32) (n int)
func Len64(x uint64) (n int)
func Len8(x uint8) int
func Mul(x, y uint) (hi, lo uint)
func Mul32(x, y uint32) (hi, lo uint32)
func Mul64(x, y uint64) (hi, lo uint64)
func OnesCount(x uint) int
func OnesCount16(x uint16) int
func OnesCount32(x uint32) int
func OnesCount64(x uint64) int
func OnesCount8(x uint8) int
func Reverse(x uint) uint
func Reverse16(x uint16) uint16
func Reverse32(x uint32) uint32
func Reverse64(x uint64) uint64
func Reverse8(x uint8) uint8
func ReverseBytes(x uint) uint
func ReverseBytes16(x uint16) uint16
func ReverseBytes32(x uint32) uint32
func ReverseBytes64(x uint64) uint64
func RotateLeft(x uint, k int) uint
func RotateLeft16(x uint16, k int) uint16
func RotateLeft32(x uint32, k int) uint32
func RotateLeft64(x uint64, k int) uint64
func RotateLeft8(x uint8, k int) uint8
func Sub(x, y, borrow uint) (diff, borrowOut uint)
func Sub32(x, y, borrow uint32) (diff, borrowOut uint32)
func Sub64(x, y, borrow uint64) (diff, borrowOut uint64)
func TrailingZeros(x uint) int
func TrailingZeros16(x uint16) int
func TrailingZeros32(x uint32) int
func TrailingZeros64(x uint64) int
func TrailingZeros8(x uint8) int

Package files

bits.go bits_tables.go

Constants

UintSize is the size of a uint in bits. 

const UintSize = uintSize

func Add 

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 

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 

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 

func LeadingZeros(x uint) int

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

func LeadingZeros16 

func LeadingZeros16(x uint16) int

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

▾ Example

Code:

fmt.Printf("LeadingZeros16(%016b) = %d\n", 1, bits.LeadingZeros16(1))

Output:

LeadingZeros16(0000000000000001) = 15

func LeadingZeros32 

func LeadingZeros32(x uint32) int

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

▾ Example

Code:

fmt.Printf("LeadingZeros32(%032b) = %d\n", 1, bits.LeadingZeros32(1))

Output:

LeadingZeros32(00000000000000000000000000000001) = 31

func LeadingZeros64 

func LeadingZeros64(x uint64) int

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

▾ Example

Code:

fmt.Printf("LeadingZeros64(%064b) = %d\n", 1, bits.LeadingZeros64(1))

Output:

LeadingZeros64(0000000000000000000000000000000000000000000000000000000000000001) = 63

func LeadingZeros8 

func LeadingZeros8(x uint8) int

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

▾ Example

Code:

fmt.Printf("LeadingZeros8(%08b) = %d\n", 1, bits.LeadingZeros8(1))

Output:

LeadingZeros8(00000001) = 7

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

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

Code:

fmt.Printf("TrailingZeros8(%08b) = %d\n", 14, bits.TrailingZeros8(14))

Output:

TrailingZeros8(00001110) = 1