bitmap

README

bitmap

bitmap implements bitmap manipulation functions for byte slices of arbitrary size.

Installation

go get github.com/anexia-it/bitmap

Contributing

Contributions are always welcome, in every possible way. We are always happy to receive bug reports and pull requests.

License

bitmap is free software, licensed under the MIT license.

Documentation

Overview

Package bitmap provides functions for working with bitmaps stored as byte slices of arbitrary size

Index

• func Clear(b []byte, bit uint)
• func IsSet(b []byte, bit uint) bool
• func Mask(b []byte, mask []byte) (masked []byte, err error)
• func Set(b []byte, bit uint)

Examples

• Clear
• IsSet
• Mask
• Set

Functions

func Clear

func Clear(b []byte, bit uint)

Clear clears a bit inside a given byte slice

Example

package main

import (
	"fmt"

	"github.com/anexia-it/bitmap"
)

func main() {
	m := []byte{0x80 | 0x40, 0x00, 0x00, 0x01}
	bitmap.Clear(m, 31)
	fmt.Printf("%x\n", m)
}

Output:

40000001

func IsSet

func IsSet(b []byte, bit uint) bool

IsSet checks if a bit is set inside a given byte slice

Example

package main

import (
	"fmt"

	"github.com/anexia-it/bitmap"
)

func main() {
	m := []byte{0xf0, 0x0f}

	fmt.Printf("%t %t %t %t %t %t %t %t %t %t %t %t %t %t %t %t",
		bitmap.IsSet(m, 0),
		bitmap.IsSet(m, 1),
		bitmap.IsSet(m, 2),
		bitmap.IsSet(m, 3),
		bitmap.IsSet(m, 4),
		bitmap.IsSet(m, 5),
		bitmap.IsSet(m, 6),
		bitmap.IsSet(m, 7),

		bitmap.IsSet(m, 8),
		bitmap.IsSet(m, 9),
		bitmap.IsSet(m, 10),
		bitmap.IsSet(m, 11),
		bitmap.IsSet(m, 12),
		bitmap.IsSet(m, 13),
		bitmap.IsSet(m, 14),
		bitmap.IsSet(m, 15),
	)
}

Output:

true true true true false false false false false false false false true true true true

func Mask

func Mask(b []byte, mask []byte) (masked []byte, err error)

Mask applies the given mask to a given byte slice

Example

package main

import (
	"fmt"

	"github.com/anexia-it/bitmap"
)

func main() {
	m := []byte{0x75}
	mask := []byte{0x5b}

	masked, err := bitmap.Mask(m, mask)
	if err != nil {
		panic(err)
	}
	fmt.Printf("%x\n", masked)
}

Output:

51

func Set

func Set(b []byte, bit uint)

Set sets a bit inside a given byte slice

Example

package main

import (
	"fmt"

	"github.com/anexia-it/bitmap"
)

func main() {
	m := make([]byte, 4)
	bitmap.Set(m, 0)
	bitmap.Set(m, 31)

	fmt.Printf("%x\n", m)
}

Output:

80000001