crc32

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

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namespace crc32

module crc32 = 
  let crc_table = [|
    0x00000000u; 0x77073096u; 0xEE0E612Cu; 0x990951BAu; 0x076DC419u; 0x706AF48Fu
    0xE963A535u; 0x9E6495A3u; 0x0EDB8832u; 0x79DCB8A4u; 0xE0D5E91Eu; 0x97D2D988u
    0x09B64C2Bu; 0x7EB17CBDu; 0xE7B82D07u; 0x90BF1D91u; 0x1DB71064u; 0x6AB020F2u
    0xF3B97148u; 0x84BE41DEu; 0x1ADAD47Du; 0x6DDDE4EBu; 0xF4D4B551u; 0x83D385C7u
    0x136C9856u; 0x646BA8C0u; 0xFD62F97Au; 0x8A65C9ECu; 0x14015C4Fu; 0x63066CD9u
    0xFA0F3D63u; 0x8D080DF5u; 0x3B6E20C8u; 0x4C69105Eu; 0xD56041E4u; 0xA2677172u
    0x3C03E4D1u; 0x4B04D447u; 0xD20D85FDu; 0xA50AB56Bu; 0x35B5A8FAu; 0x42B2986Cu
    0xDBBBC9D6u; 0xACBCF940u; 0x32D86CE3u; 0x45DF5C75u; 0xDCD60DCFu; 0xABD13D59u
    0x26D930ACu; 0x51DE003Au; 0xC8D75180u; 0xBFD06116u; 0x21B4F4B5u; 0x56B3C423u
    0xCFBA9599u; 0xB8BDA50Fu; 0x2802B89Eu; 0x5F058808u; 0xC60CD9B2u; 0xB10BE924u
    0x2F6F7C87u; 0x58684C11u; 0xC1611DABu; 0xB6662D3Du; 0x76DC4190u; 0x01DB7106u
    0x98D220BCu; 0xEFD5102Au; 0x71B18589u; 0x06B6B51Fu; 0x9FBFE4A5u; 0xE8B8D433u
    0x7807C9A2u; 0x0F00F934u; 0x9609A88Eu; 0xE10E9818u; 0x7F6A0DBBu; 0x086D3D2Du
    0x91646C97u; 0xE6635C01u; 0x6B6B51F4u; 0x1C6C6162u; 0x856530D8u; 0xF262004Eu
    0x6C0695EDu; 0x1B01A57Bu; 0x8208F4C1u; 0xF50FC457u; 0x65B0D9C6u; 0x12B7E950u
    0x8BBEB8EAu; 0xFCB9887Cu; 0x62DD1DDFu; 0x15DA2D49u; 0x8CD37CF3u; 0xFBD44C65u
    0x4DB26158u; 0x3AB551CEu; 0xA3BC0074u; 0xD4BB30E2u; 0x4ADFA541u; 0x3DD895D7u
    0xA4D1C46Du; 0xD3D6F4FBu; 0x4369E96Au; 0x346ED9FCu; 0xAD678846u; 0xDA60B8D0u
    0x44042D73u; 0x33031DE5u; 0xAA0A4C5Fu; 0xDD0D7CC9u; 0x5005713Cu; 0x270241AAu
    0xBE0B1010u; 0xC90C2086u; 0x5768B525u; 0x206F85B3u; 0xB966D409u; 0xCE61E49Fu
    0x5EDEF90Eu; 0x29D9C998u; 0xB0D09822u; 0xC7D7A8B4u; 0x59B33D17u; 0x2EB40D81u
    0xB7BD5C3Bu; 0xC0BA6CADu; 0xEDB88320u; 0x9ABFB3B6u; 0x03B6E20Cu; 0x74B1D29Au
    0xEAD54739u; 0x9DD277AFu; 0x04DB2615u; 0x73DC1683u; 0xE3630B12u; 0x94643B84u
    0x0D6D6A3Eu; 0x7A6A5AA8u; 0xE40ECF0Bu; 0x9309FF9Du; 0x0A00AE27u; 0x7D079EB1u
    0xF00F9344u; 0x8708A3D2u; 0x1E01F268u; 0x6906C2FEu; 0xF762575Du; 0x806567CBu
    0x196C3671u; 0x6E6B06E7u; 0xFED41B76u; 0x89D32BE0u; 0x10DA7A5Au; 0x67DD4ACCu
    0xF9B9DF6Fu; 0x8EBEEFF9u; 0x17B7BE43u; 0x60B08ED5u; 0xD6D6A3E8u; 0xA1D1937Eu
    0x38D8C2C4u; 0x4FDFF252u; 0xD1BB67F1u; 0xA6BC5767u; 0x3FB506DDu; 0x48B2364Bu
    0xD80D2BDAu; 0xAF0A1B4Cu; 0x36034AF6u; 0x41047A60u; 0xDF60EFC3u; 0xA867DF55u
    0x316E8EEFu; 0x4669BE79u; 0xCB61B38Cu; 0xBC66831Au; 0x256FD2A0u; 0x5268E236u
    0xCC0C7795u; 0xBB0B4703u; 0x220216B9u; 0x5505262Fu; 0xC5BA3BBEu; 0xB2BD0B28u
    0x2BB45A92u; 0x5CB36A04u; 0xC2D7FFA7u; 0xB5D0CF31u; 0x2CD99E8Bu; 0x5BDEAE1Du
    0x9B64C2B0u; 0xEC63F226u; 0x756AA39Cu; 0x026D930Au; 0x9C0906A9u; 0xEB0E363Fu
    0x72076785u; 0x05005713u; 0x95BF4A82u; 0xE2B87A14u; 0x7BB12BAEu; 0x0CB61B38u
    0x92D28E9Bu; 0xE5D5BE0Du; 0x7CDCEFB7u; 0x0BDBDF21u; 0x86D3D2D4u; 0xF1D4E242u
    0x68DDB3F8u; 0x1FDA836Eu; 0x81BE16CDu; 0xF6B9265Bu; 0x6FB077E1u; 0x18B74777u
    0x88085AE6u; 0xFF0F6A70u; 0x66063BCAu; 0x11010B5Cu; 0x8F659EFFu; 0xF862AE69u
    0x616BFFD3u; 0x166CCF45u; 0xA00AE278u; 0xD70DD2EEu; 0x4E048354u; 0x3903B3C2u
    0xA7672661u; 0xD06016F7u; 0x4969474Du; 0x3E6E77DBu; 0xAED16A4Au; 0xD9D65ADCu
    0x40DF0B66u; 0x37D83BF0u; 0xA9BCAE53u; 0xDEBB9EC5u; 0x47B2CF7Fu; 0x30B5FFE9u
    0xBDBDF21Cu; 0xCABAC28Au; 0x53B39330u; 0x24B4A3A6u; 0xBAD03605u; 0xCDD70693u
    0x54DE5729u; 0x23D967BFu; 0xB3667A2Eu; 0xC4614AB8u; 0x5D681B02u; 0x2A6F2B94u
    0xB40BBE37u; 0xC30C8EA1u; 0x5A05DF1Bu; 0x2D02EF8Du
    |]  
    
  let generate (b : byte array) =
   
    let buf = b |> Array.map uint32
    
    (* eww *)
    let c = ref (0u ^^^ 0xffffffffu)
    for n = 0 to buf.Length - 1 do
      c := crc_table.[int( (!c ^^^ buf.[n]) &&& 0xffu )] ^^^ (!c >>> 8)
    c := (!c ^^^ 0xffffffffu)
    
    (* gzip stuff *)
    [| 24; 16; 8; 0 |] 
    |> Array.map(fun bit -> (!c >>> bit) &&& 0xffu)
    |> Array.rev

module crc32

from crc32

namespace crc32

val crc_table : uint32 []

Full name: crc32.crc32.crc_table

val generate : b:byte array -> uint32 []

Full name: crc32.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 : uint32 []

module Array

from Microsoft.FSharp.Collections

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

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

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

val c : uint32 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 bit : int

val rev : array:'T [] -> 'T []

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

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More information

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