cuint

C-like unsigned integers for Javascript

Synopsis

Javascript does not natively support handling of unsigned 32 or 64 bits integers. This library provides that functionality, following C behaviour, enabling the writing of algorithms that depend on it. It was designed with performance in mind and tries its best to be as fast as possible. Any improvement is welcome!

How it works

An unsigned 32 bits integer is represented by an object with its first 16 bits (low bits) and its 16 last ones (high bits). All the supported standard operations on the unsigned integer are then performed transparently.

e.g.
10000010000100000100010000100010 (2182104098 or 0x82104422) is represented by:
high=1000001000010000
low= 0100010000100010

NB. In case of overflow, the unsigned integer is truncated to its lowest 32 bits (in case of UINT32) or 64 bits (in case of UINT64).

The same applies to 64 bits integers, which are split into 4 16 bits ones.

Installation

In nodejs:

npm install cuint

In the browser, include the following (file is located in the build directory), and access the constructor with UINT32:

` ...

`

Usage

To instantiate an unsigned 32 bits integer, do any of the following:

var UINT32 = require('cuint').UINT32 // NodeJS
UINT32( <low bits>, <high bits> )
UINT32( <number> )
UINT32( '<number>', <radix> ) // radix = 10 by default

To instantiate an unsigned 64 bits integer, do any of the following:

var UINT64 = require('cuint').UINT64 // NodeJS
UINT64( <low bits>, <high bits> )
UINT64( <first low bits>, <second low bits>, <first high bits>, <second high bits> )
UINT64( <number> )
UINT64( '<number>', <radix> ) // radix = 10 by default

Important

Most methods do modify the object they are applied to. For instance, the following is equivalent to x += y

UINT(x).add( UINT(y) )

This allows for chaining and reduces the cost of the emulation. To have z = x + y, do the following:

z = UINT(x).clone().add( UINT(y) )

Examples for UINT32

• Using low and high bits

UINT32( 2, 1 ) // 65538 { remainder: null, _low: 2, _high: 1 }

• Using a number (signed 32 bits integer)

UINT32( 65538 ) // 65538 { remainder: null, _low: 2, _high: 1 }

• Using a string

UINT32( '65538' ) // 65538 { remainder: null, _low: 2, _high: 1 }

• Using another string

UINT32( '3266489917' ) { remainder: null, _low: 44605, _high: 49842 }

• Divide 2 unsigned 32 bits integers - note that the remainder is also provided

UINT32( '3266489917' ).div( UINT32( '668265263' ) ) { remainder: { remainder: null , _low: 385 , _high: 9055 } , _low: 4 , _high: 0 }

Examples for UINT64

• Using low and high bits

UINT64( 2, 1 ) // 4294967298 { remainder: null, _a00: 2, _a16: 0, _a32: 1, _a48: 0 }

• Using first/second low and high bits

UINT64( 2, 1, 0, 0 ) // 65538 { remainder: null, _a00: 2, _a16: 1, _a32: 0, _a48: 0 }

• Using a number (signed 32 bits integer)

UINT64( 65538 ) // 65538 { remainder: null, _a00: 2, _a16: 1, _a32: 0, _a48: 0 }

• Using a string

UINT64( '65538' ) // 65538 { remainder: null, _a00: 2, _a16: 1, _a32: 0, _a48: 0 }

• Using another string

UINT64( '3266489917' ) { remainder: null, _a00: 44605, _a16: 49842, _a32: 0, _a48: 0 }

• Divide 2 unsigned 64 bits integers - note that the remainder is also provided

UINT64( 'F00000000000', 16 ).div( UINT64( '800000000000', 16 ) ) { remainder: { remainder: null, _a00: 0, _a16: 0, _a32: 28672, _a48: 0 }, _a00: 1, _a16: 0, _a32: 0, _a48: 0 }

Methods

Methods specific to UINT32 and UINT64:

• UINT32.fromBits(<low bits>, <high bits>)* Set the current UINT32 object with its low and high bits
• UINT64.fromBits(<low bits>, <high bits>)* Set the current UINT64 object with its low and high bits
• UINT64.fromBits(<first low bits>, <second low bits>, <first high bits>, <second high bits>)* Set the current UINT64 object with all its low and high bits

Methods common to UINT32 and UINT64:

• UINT.fromNumber(<number>)* Set the current UINT object from a number (first 32 bits only)
• UINT.fromString(<string>, <radix>) Set the current UINT object from a string
• UINT.toNumber() Convert this UINT to a number
• UINT.toString(<radix>) Convert this UINT to a string
• UINT.add(<uint>)* Add two UINT. The current UINT stores the result
• UINT.subtract(<uint>)* Subtract two UINT. The current UINT stores the result
• UINT.multiply(<uint>)* Multiply two UINT. The current UINT stores the result
• UINT.div(<uint>)* Divide two UINT. The current UINT stores the result. The remainder is made available as the remainder property on the UINT object. It can be null, meaning there are no remainder.
• UINT.negate() Negate the current UINT
• UINT.equals(<uint>) alias UINT.eq(<uint>) Equals
• UINT.lessThan(<uint>) alias UINT.lt(<uint>) Less than (strict)
• UINT.greaterThan(<uint>) alias UINT.gt(<uint>) Greater than (strict)
• UINT.not() Bitwise NOT
• UINT.or(<uint>)* Bitwise OR
• UINT.and(<uint>)* Bitwise AND
• UINT.xor(<uint>)* Bitwise XOR
• UINT.shiftRight(<number>)* alias UINT.shiftr(<number>)* Bitwise shift right
• UINT.shiftLeft(<number>[, <allowOverflow>])* alias UINT.shiftl(<number>[, <allowOverflow>])* Bitwise shift left
• UINT.rotateLeft(<number>)* alias UINT.rotl(<number>)* Bitwise rotate left
• UINT.rotateRight(<number>)* alias UINT.rotr(<number>)* Bitwise rotate right
• UINT.clone() Clone the current UINT

NB. methods with an * do modify the object it is applied to. Input objects are not modified.

TODO

• more methods:
  • pow
  • log
  • sqrt
  • ...
• signed version

License

MIT

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