https://github.com/ktonon/elm-word

Unsigned 32 or 64 bit integers and related operations
https://github.com/ktonon/elm-word

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Unsigned 32 or 64 bit integers and related operations

• Host: GitHub
• URL: https://github.com/ktonon/elm-word
• Owner: ktonon
• License: mit
• Created: 2017-08-24T01:22:32.000Z (over 7 years ago)
• Default Branch: master
• Last Pushed: 2018-12-18T01:16:53.000Z (about 6 years ago)
• Last Synced: 2023-08-08T20:39:30.208Z (over 1 year ago)
• Language: Elm
• Size: 46.9 KB
• Stars: 1
• Watchers: 2
• Forks: 4
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# elm-word

[![elm-package](https://img.shields.io/badge/elm-2.1.2-blue.svg)](http://package.elm-lang.org/packages/ktonon/elm-word/latest)

[![CircleCI](https://img.shields.io/circleci/project/github/ktonon/elm-word.svg)](https://circleci.com/gh/ktonon/elm-word)

Unsigned 32 or 64 bit integers and related operations.

Use the `Word` type to hold either 32 or 64 bit unsigned integers. Use the exposed type constructors `W` (for "word") and `D` (for "double word") to store values as words.

```elm

import Word exposing (Word(D, W))

```

## Operations

The following operations are provided.

* `add` - modulo addition

* `and` - bitwise and

* `xor` - bitwise xor

* `complement` - bitwise inversion

* `rotateRightBy` - [rotate right][]

* `shiftRightZfBy` - [logical shift right][]

Note that the set of operations is the minimal required to implement [SHA-2][].

## Examples

Addition of words is modulo 32 bits.

```elm

add (W 0x80000000)

    (W 0x80000003)

--> W 3

```

Addition of double words is modulo 64 bits.

```elm

add (D 0 0xFFFFFFFF)

    (D 0 1)

--> D 1 0

```

## Large Values in Elm

Double words are stored as two 32 bit values because Elm makes arithmetic mistakes with larger values. For example, try typing this into the `elm repl`:

```shell

$ elm repl

---- elm-repl 0.18.0 -----------------------------------------------------------

> 2 ^ 60 + 55 == 2 ^ 60

True : Bool

```

## Related Libraries

* [gilbertkennen/bigint][]: Work with integers of unlimited size.

* [mthadley/elm-byte][]: A library for working with 8-bit unsigned integers with type safety.

[gilbertkennen/bigint]:http://package.elm-lang.org/packages/gilbertkennen/bigint/latest/

[logical shift right]:https://en.wikipedia.org/wiki/Bitwise_operation#Logical_shift

[mthadley/elm-byte]:http://package.elm-lang.org/packages/mthadley/elm-byte/latest

[rotate right]:https://en.wikipedia.org/wiki/Bitwise_operation#Rotate_no_carry

[SHA-2]:https://en.wikipedia.org/wiki/SHA-2