JarCastingC-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:
`<script src="/your/path/to/uint32.js"></script> ...
<script type="text/javascript"> var v1 = UINT32('326648991'); var v2 = UINT32('265443576'); var v1plus2 = v1.add(v2) // 592092567 </script>`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 bitsUINT64.fromBits(<low bits>, <high bits>)*Set the current UINT64 object with its low and high bitsUINT64.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 stringUINT.toNumber()Convert this UINT to a numberUINT.toString(<radix>)Convert this UINT to a stringUINT.add(<uint>)*Add two UINT. The current UINT stores the resultUINT.subtract(<uint>)*Subtract two UINT. The current UINT stores the resultUINT.multiply(<uint>)*Multiply two UINT. The current UINT stores the resultUINT.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 UINTUINT.equals(<uint>)aliasUINT.eq(<uint>)EqualsUINT.lessThan(<uint>)aliasUINT.lt(<uint>)Less than (strict)UINT.greaterThan(<uint>)aliasUINT.gt(<uint>)Greater than (strict)UINT.not()Bitwise NOTUINT.or(<uint>)*Bitwise ORUINT.and(<uint>)*Bitwise ANDUINT.xor(<uint>)*Bitwise XORUINT.shiftRight(<number>)*aliasUINT.shiftr(<number>)*Bitwise shift rightUINT.shiftLeft(<number>[, <allowOverflow>])*aliasUINT.shiftl(<number>[, <allowOverflow>])*Bitwise shift leftUINT.rotateLeft(<number>)*aliasUINT.rotl(<number>)*Bitwise rotate leftUINT.rotateRight(<number>)*aliasUINT.rotr(<number>)*Bitwise rotate rightUINT.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
Written with StackEdit.