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Unit zCompres;
{ compress.c -- compress a memory buffer
Copyright (C) 1995-1998 Jean-loup Gailly.
Pascal tranlastion
Copyright (C) 1998 by Jacques Nomssi Nzali
For conditions of distribution and use, see copyright notice in readme.txt
}
interface
{$I zconf.inc}
uses
zutil, zbase, zDeflate;
{ utility functions }
{EXPORT}
function compress (dest : pBytef;
var destLen : uLong;
source : pBytef;
sourceLen : uLong) : int;
{ Compresses the source buffer into the destination buffer. sourceLen is
the byte length of the source buffer. Upon entry, destLen is the total
size of the destination buffer, which must be at least 0.1% larger than
sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
compressed buffer.
This function can be used to compress a whole file at once if the
input file is mmap'ed.
compress returns Z_OK if success, Z_MEM_ERROR if there was not
enough memory, Z_BUF_ERROR if there was not enough room in the output
buffer. }
{EXPORT}
function compress2 (dest : pBytef;
var destLen : uLong;
source : pBytef;
sourceLen : uLong;
level : int) : int;
{ Compresses the source buffer into the destination buffer. The level
parameter has the same meaning as in deflateInit. sourceLen is the byte
length of the source buffer. Upon entry, destLen is the total size of the
destination buffer, which must be at least 0.1% larger than sourceLen plus
12 bytes. Upon exit, destLen is the actual size of the compressed buffer.
compress2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
memory, Z_BUF_ERROR if there was not enough room in the output buffer,
Z_STREAM_ERROR if the level parameter is invalid. }
implementation
{ ===========================================================================
}
function compress2 (dest : pBytef;
var destLen : uLong;
source : pbytef;
sourceLen : uLong;
level : int) : int;
var
stream : z_stream;
err : int;
begin
stream.next_in := source;
stream.avail_in := uInt(sourceLen);
{$ifdef MAXSEG_64K}
{ Check for source > 64K on 16-bit machine: }
if (uLong(stream.avail_in) <> sourceLen) then
begin
compress2 := Z_BUF_ERROR;
exit;
end;
{$endif}
stream.next_out := dest;
stream.avail_out := uInt(destLen);
if (uLong(stream.avail_out) <> destLen) then
begin
compress2 := Z_BUF_ERROR;
exit;
end;
stream.zalloc := NIL; { alloc_func(0); }
stream.zfree := NIL; { free_func(0); }
stream.opaque := NIL; { voidpf(0); }
err := deflateInit(stream, level);
if (err <> Z_OK) then
begin
compress2 := err;
exit;
end;
err := deflate(stream, Z_FINISH);
if (err <> Z_STREAM_END) then
begin
deflateEnd(stream);
if err = Z_OK then
compress2 := Z_BUF_ERROR
else
compress2 := err;
exit;
end;
destLen := stream.total_out;
err := deflateEnd(stream);
compress2 := err;
end;
{ ===========================================================================
}
function compress (dest : pBytef;
var destLen : uLong;
source : pBytef;
sourceLen : uLong) : int;
begin
compress := compress2(dest, destLen, source, sourceLen, Z_DEFAULT_COMPRESSION);
end;
end.
|
