bitwise-rotation

Rotate values with a bitwise rotation.

In computer programming, a circular shift (or bitwise rotation) is a shift operator that shifts all bits of its operand. Unlike an arithmetic shift, a circular shift does not preserve a number's sign bit or distinguish a number's exponent from its significand (sometimes referred to as the mantissa). — Wikipedia

How to Use

import bitwiseRotation from 'bitwise-rotation';

// Set the bit-width/length; max of `32`, min of `0`.
const rotationObject = bitwiseRotation(8);

// Returns an object with rotate right (`ror`) and rotate left (`rol`) methods.
const { ror, rol } = rotationObject;

// Rotate a value by an amount.
rol(101, 2); // 149
ror(101, 2); // 89

Visual Example

import { rolInt8, rorInt8 } from 'bitwise-rotation';

const value = 1;
value.toString(2);             // 00000001
rolInt8(value, 1).toString(2); // 00000010
rolInt8(value, 2).toString(2); // 00000100
rolInt8(value, 3).toString(2); // 00001000
rolInt8(value, 4).toString(2); // 00010000
rorInt8(value, 4).toString(2); // 00010000
rorInt8(value, 3).toString(2); // 00100000
rorInt8(value, 2).toString(2); // 01000000
rorInt8(value, 1).toString(2); // 10000000

API

bitwiseRotation(bitWidth) (default)

A function to specify a custom bitWidth that returns a rotationObject.

• bitWidth: An integer between [0, 32] that specifies the limit for rotating values.

bitWidth cannot be larger than 32 because operands of all bitwise operators are converted to signed 32-bit integers in two's complement format. — MDN

rotationObject

An object with the following 2 methods for rotating bytes:

• ror(value, rotation): Rotate a byte to the right by the specified amount of rotation.

  • value: Decimal representation of a value to be rotated.

  • rotation: The amount to rotate the value by.

• rol(value, rotation): Rotate a byte to the left by the specified amount of rotation.

  • value: Decimal representation of a byte to be rotated.

  • rotation: The amount to rotate the value by.

Both methods return a decimal representation of a value rotated.

rorInt8(value, rotation)

Convenience method for rotating an 8-bit value right.

rolInt8(value, rotation)

Convenience method for rotating an 8-bit value left.

rorInt16(value, rotation)

Convenience method for rotating a 16-bit value right.

rolInt16(value, rotation)

Convenience method for rotating a 16-bit value left.

rorInt32(value, rotation)

Convenience method for rotating a 32-bit value right.

rolInt32(value, rotation)

Convenience method for rotating a 32-bit value left.