CRC-32 implementation

An implementation of a CRC-32 algorithm, as described in RFC-1952 "GZIP file format specification version 4.3"

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module private Internal =
    let crcTable = 
        let inline nextValue acc =
            if 0u <> (acc &&& 1u) then 0xedb88320u ^^^ (acc >>> 1) else acc >>> 1
        let rec iter k acc =
            if k = 0 then acc else iter (k-1) (nextValue acc)
        [| 0u .. 255u |] |> Array.map (iter 8)


/// Returns the CRC-32 value of 'name' as specified by RFC1952
let crc32 (name:string) =
    let inline update acc (ch:char) =
        Internal.crcTable.[int32 ((acc ^^^ (uint32 ch)) &&& 0xffu)] ^^^ (acc >>> 8)
    0xFFffFFffu ^^^ Seq.fold update 0xFFffFFffu name

val private crcTable : uint32 []

Full name: Script.Internal.crcTable

val nextValue : (uint32 -> uint32)

val acc : uint32

val iter : (int -> uint32 -> uint32)

val k : int

module Array

from Microsoft.FSharp.Collections

val map : mapping:('T -> 'U) -> array:'T [] -> 'U []

Full name: Microsoft.FSharp.Collections.Array.map

val crc32 : name:string -> uint32

Full name: Script.crc32

Returns the CRC-32 value of 'name' as specified by RFC1952

val name : string

Multiple items
val string : value:'T -> string

Full name: Microsoft.FSharp.Core.Operators.string

--------------------
type string = System.String

Full name: Microsoft.FSharp.Core.string

val update : (uint32 -> char -> uint32)

val ch : char

Multiple items
val char : value:'T -> char (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.char

--------------------
type char = System.Char

Full name: Microsoft.FSharp.Core.char

module Internal

from Script

Multiple items
val int32 : value:'T -> int32 (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.int32

--------------------
type int32 = System.Int32

Full name: Microsoft.FSharp.Core.int32

Multiple items
val uint32 : value:'T -> uint32 (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.uint32

--------------------
type uint32 = System.UInt32

Full name: Microsoft.FSharp.Core.uint32

module Seq

from Microsoft.FSharp.Collections

val fold : folder:('State -> 'T -> 'State) -> state:'State -> source:seq<'T> -> 'State

Full name: Microsoft.FSharp.Collections.Seq.fold

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More information

Link:	http://fssnip.net/dS
Posted:	12 years ago
Author:	Henrik Ravn
Tags:	crc