crc32

have a project to write some basics from gzip, needed crc32, seems fast enough, fixed one bug!

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module crc32 = 
  let crc_table = [|
    0x00000000L; 0x77073096L; 0xEE0E612CL; 0x990951BAL; 0x076DC419L; 0x706AF48FL
    0xE963A535L; 0x9E6495A3L; 0x0EDB8832L; 0x79DCB8A4L; 0xE0D5E91EL; 0x97D2D988L
    0x09B64C2BL; 0x7EB17CBDL; 0xE7B82D07L; 0x90BF1D91L; 0x1DB71064L; 0x6AB020F2L
    0xF3B97148L; 0x84BE41DEL; 0x1ADAD47DL; 0x6DDDE4EBL; 0xF4D4B551L; 0x83D385C7L
    0x136C9856L; 0x646BA8C0L; 0xFD62F97AL; 0x8A65C9ECL; 0x14015C4FL; 0x63066CD9L
    0xFA0F3D63L; 0x8D080DF5L; 0x3B6E20C8L; 0x4C69105EL; 0xD56041E4L; 0xA2677172L
    0x3C03E4D1L; 0x4B04D447L; 0xD20D85FDL; 0xA50AB56BL; 0x35B5A8FAL; 0x42B2986CL
    0xDBBBC9D6L; 0xACBCF940L; 0x32D86CE3L; 0x45DF5C75L; 0xDCD60DCFL; 0xABD13D59L
    0x26D930ACL; 0x51DE003AL; 0xC8D75180L; 0xBFD06116L; 0x21B4F4B5L; 0x56B3C423L
    0xCFBA9599L; 0xB8BDA50FL; 0x2802B89EL; 0x5F058808L; 0xC60CD9B2L; 0xB10BE924L
    0x2F6F7C87L; 0x58684C11L; 0xC1611DABL; 0xB6662D3DL; 0x76DC4190L; 0x01DB7106L
    0x98D220BCL; 0xEFD5102AL; 0x71B18589L; 0x06B6B51FL; 0x9FBFE4A5L; 0xE8B8D433L
    0x7807C9A2L; 0x0F00F934L; 0x9609A88EL; 0xE10E9818L; 0x7F6A0DBBL; 0x086D3D2DL
    0x91646C97L; 0xE6635C01L; 0x6B6B51F4L; 0x1C6C6162L; 0x856530D8L; 0xF262004EL
    0x6C0695EDL; 0x1B01A57BL; 0x8208F4C1L; 0xF50FC457L; 0x65B0D9C6L; 0x12B7E950L
    0x8BBEB8EAL; 0xFCB9887CL; 0x62DD1DDFL; 0x15DA2D49L; 0x8CD37CF3L; 0xFBD44C65L
    0x4DB26158L; 0x3AB551CEL; 0xA3BC0074L; 0xD4BB30E2L; 0x4ADFA541L; 0x3DD895D7L
    0xA4D1C46DL; 0xD3D6F4FBL; 0x4369E96AL; 0x346ED9FCL; 0xAD678846L; 0xDA60B8D0L
    0x44042D73L; 0x33031DE5L; 0xAA0A4C5FL; 0xDD0D7CC9L; 0x5005713CL; 0x270241AAL
    0xBE0B1010L; 0xC90C2086L; 0x5768B525L; 0x206F85B3L; 0xB966D409L; 0xCE61E49FL
    0x5EDEF90EL; 0x29D9C998L; 0xB0D09822L; 0xC7D7A8B4L; 0x59B33D17L; 0x2EB40D81L
    0xB7BD5C3BL; 0xC0BA6CADL; 0xEDB88320L; 0x9ABFB3B6L; 0x03B6E20CL; 0x74B1D29AL
    0xEAD54739L; 0x9DD277AFL; 0x04DB2615L; 0x73DC1683L; 0xE3630B12L; 0x94643B84L
    0x0D6D6A3EL; 0x7A6A5AA8L; 0xE40ECF0BL; 0x9309FF9DL; 0x0A00AE27L; 0x7D079EB1L
    0xF00F9344L; 0x8708A3D2L; 0x1E01F268L; 0x6906C2FEL; 0xF762575DL; 0x806567CBL
    0x196C3671L; 0x6E6B06E7L; 0xFED41B76L; 0x89D32BE0L; 0x10DA7A5AL; 0x67DD4ACCL
    0xF9B9DF6FL; 0x8EBEEFF9L; 0x17B7BE43L; 0x60B08ED5L; 0xD6D6A3E8L; 0xA1D1937EL
    0x38D8C2C4L; 0x4FDFF252L; 0xD1BB67F1L; 0xA6BC5767L; 0x3FB506DDL; 0x48B2364BL
    0xD80D2BDAL; 0xAF0A1B4CL; 0x36034AF6L; 0x41047A60L; 0xDF60EFC3L; 0xA867DF55L
    0x316E8EEFL; 0x4669BE79L; 0xCB61B38CL; 0xBC66831AL; 0x256FD2A0L; 0x5268E236L
    0xCC0C7795L; 0xBB0B4703L; 0x220216B9L; 0x5505262FL; 0xC5BA3BBEL; 0xB2BD0B28L
    0x2BB45A92L; 0x5CB36A04L; 0xC2D7FFA7L; 0xB5D0CF31L; 0x2CD99E8BL; 0x5BDEAE1DL
    0x9B64C2B0L; 0xEC63F226L; 0x756AA39CL; 0x026D930AL; 0x9C0906A9L; 0xEB0E363FL
    0x72076785L; 0x05005713L; 0x95BF4A82L; 0xE2B87A14L; 0x7BB12BAEL; 0x0CB61B38L
    0x92D28E9BL; 0xE5D5BE0DL; 0x7CDCEFB7L; 0x0BDBDF21L; 0x86D3D2D4L; 0xF1D4E242L
    0x68DDB3F8L; 0x1FDA836EL; 0x81BE16CDL; 0xF6B9265BL; 0x6FB077E1L; 0x18B74777L
    0x88085AE6L; 0xFF0F6A70L; 0x66063BCAL; 0x11010B5CL; 0x8F659EFFL; 0xF862AE69L
    0x616BFFD3L; 0x166CCF45L; 0xA00AE278L; 0xD70DD2EEL; 0x4E048354L; 0x3903B3C2L
    0xA7672661L; 0xD06016F7L; 0x4969474DL; 0x3E6E77DBL; 0xAED16A4AL; 0xD9D65ADCL
    0x40DF0B66L; 0x37D83BF0L; 0xA9BCAE53L; 0xDEBB9EC5L; 0x47B2CF7FL; 0x30B5FFE9L
    0xBDBDF21CL; 0xCABAC28AL; 0x53B39330L; 0x24B4A3A6L; 0xBAD03605L; 0xCDD70693L
    0x54DE5729L; 0x23D967BFL; 0xB3667A2EL; 0xC4614AB8L; 0x5D681B02L; 0x2A6F2B94L
    0xB40BBE37L; 0xC30C8EA1L; 0x5A05DF1BL; 0x2D02EF8DL
    |]  
    
  let generate (b : byte array) =
    let buf = b |> Array.map int64
    let c = ref 0xffffffffL
    for n = 0 to buf.Length - 1 do
      c := crc_table.[int((!c ^^^ buf.[n]) &&& 0xffL)] ^^^ (!c >>> 8)
    sprintf "%2x" (!c ^^^ 0xffffffffL)

    (* for use with gzip...
    let h = sprintf "%2x" (!c ^^^ 0xffffffffL)

    [| h.[6..7]; h.[4..5]; h.[2..3]; h.[0..1] |] 
    |> Array.map (fun x -> byte <| sprintf "0x%2s" x)
    *)

val crc_table : int64 []

Full name: Script.crc32.crc_table

val generate : b:byte array -> string

Full name: Script.crc32.generate

val b : byte array

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

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

--------------------
type byte = System.Byte

Full name: Microsoft.FSharp.Core.byte

type 'T array = 'T []

Full name: Microsoft.FSharp.Core.array<_>

val buf : int64 []

module Array

from Microsoft.FSharp.Collections

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

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

Multiple items
val int64 : value:'T -> int64 (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.int64

--------------------
type int64 = System.Int64

Full name: Microsoft.FSharp.Core.int64

--------------------
type int64<'Measure> = int64

Full name: Microsoft.FSharp.Core.int64<_>

val c : int64 ref

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

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

--------------------
type 'T ref = Ref<'T>

Full name: Microsoft.FSharp.Core.ref<_>

val n : int

property System.Array.Length: int

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

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

--------------------
type int = int32

Full name: Microsoft.FSharp.Core.int

--------------------
type int<'Measure> = int

Full name: Microsoft.FSharp.Core.int<_>

val sprintf : format:Printf.StringFormat<'T> -> 'T

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.sprintf

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More information

Link:	http://fssnip.net/cG
Posted:	12 years ago
Author:	David Klein
Tags:	crc32 , gzip