Classic ASP
Decompress Large Text File in Blocks

Decompresses a large text file in blocks, and compares the restored (decompressed) file with the original to make sure it's correct.
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Classic ASP
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

' This example requires the Chilkat API to have been previously unlocked.
' See Global Unlock Sample for sample code.

' First, let's compress a text file.
' We'll then decompress in blocks, and compare the decompressed with the original file.

' Compress a text file:
set compress = Server.CreateObject("Chilkat.Compression")
compress.Algorithm = "deflate"

success = compress.CompressFile("qa_data/hamlet.xml","qa_data/hamlet_compressed.dat")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( compress.LastErrorText) & "</pre>"
    Response.End
End If

set fac = Server.CreateObject("Chilkat.FileAccess")

' Examine the uncompressed and compressed sizes:
originalPath = "qa_data/hamlet.xml"
' Note: The FileSize method returns a signed 32-bit integer.  If the file is potentially larger than 2GB, call FileSizeStr instead to return
' the size of the file as a string, then convert to an integer value.
Response.Write "<pre>" & Server.HTMLEncode( "uncompressed size: " & fac.FileSize(originalPath)) & "</pre>"
Response.Write "<pre>" & Server.HTMLEncode( "compressed size: " & fac.FileSize("qa_data/hamlet_compressed.dat")) & "</pre>"

' Decompress in blocks..
set facSrc = Server.CreateObject("Chilkat.FileAccess")
set facDest = Server.CreateObject("Chilkat.FileAccess")

success = facSrc.OpenForRead("qa_data/hamlet_compressed.dat")

' If we compress in 32K chunks, find out how many blocks there will be.
blockSize = 32768
numBlocks = facSrc.GetNumBlocks(blockSize)

' Open an output file for the decompressed data.
restoredPath = "qa_output/hamlet_restored.xml"
success = facDest.OpenForWrite(restoredPath)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( facDest.LastErrorText) & "</pre>"
    Response.End
End If

' Assuming numBlocks > 1
compress.FirstChunk = 1
compress.LastChunk = 0

i = 0
Do While i < numBlocks
    compressedBytes = facSrc.ReadBlock(i,blockSize)
    decompressedStr = compress.DecompressString(compressedBytes)

    success = facDest.AppendText(decompressedStr,"utf-8")

    i = i + 1

    compress.FirstChunk = 0
    If (i = (numBlocks - 1)) Then
        compress.LastChunk = 1
    End If

Loop

facSrc.FileClose 
facDest.FileClose 

' Examine the size of the restored file.
Response.Write "<pre>" & Server.HTMLEncode( "restored size: " & fac.FileSize(restoredPath)) & "</pre>"

' Compare the contents of the original with the restored.
bEqualContents = fac.FileContentsEqual(restoredPath,originalPath)
Response.Write "<pre>" & Server.HTMLEncode( "Contents Equal: " & bEqualContents) & "</pre>"

%>
</body>
</html>