On Thu, 10 Jan 2008, Lorenzo Fiorini wrote:
> Actually I don't need HB_UNCOMPRESS since that part is done by Firefox
> I've simply to provide the compressed data but reading the code I have
> seen that lit want the len or a buffer with len as second parameter.
Yes, and it should greater or equal then the size of decompressed data.
> How could I know it?
1. You can guess it,
2. You can use some arbitrary big value which you know it will be
always bigger then size of decompressed data
3. You can store the size with compressed data, f.e. in first 4 bytes
using L2BIN(), f.e.:
cCompressed := L2BIN( LEN( cData ) ) + HB_COMPRESS( cData )
...
cData := HB_DECOMPRESS( SUBSTR( cCompressed, 5 ), BIN2L( cCompressed ) )
4. If speed is less important then you can add dummy decompress pass to
calculate the size of decompress data using function:
HB_UNCOMPRESSLEN( <cCompressedData> ) -> <nUnCompressedDataLen>
Code is attached below, add it to hbzlib.c
> I mean is it possible a simple cZipped := HB_COMPRESS( cNormal ) --
> rpc ---> cNormal := HB_UNCOMPRESS( cZipped )?
I can add support for HB_UNCOMPRESS( cZipped ) by calling internally
hb_zlibUncompressedSize() but in such case people used to forget
about the real cost (speed overhead) of such features so maybe is better
to force calling:
HB_UNCOMPRESS( cZipped, HB_UNCOMPRESSLEN( cZipped ) )
???
best regards,
Przemek
static ULONG hb_zlibUncompressedSize( const char * szSrc, ULONG ulLen )
{
Byte buffer[ 1024 ];
z_stream stream;
ULONG ulDest = 0;
memset( &stream, 0, sizeof( z_stream ) );
stream.next_in = ( Bytef * ) szSrc;
stream.avail_in = ( uInt ) ulLen;
if( inflateInit( &stream ) == Z_OK )
{
int iStatus;
do
{
stream.next_out = buffer;
stream.avail_out = sizeof( buffer );
iStatus = inflate( &stream, Z_NO_FLUSH );
}
while( iStatus == Z_OK );
if( iStatus == Z_STREAM_END )
ulDest = stream.total_out;
inflateEnd( &stream );
}
return ulDest;
}
/*
* HB_UNCOMPRESSLEN( <cCompressedData> ) -> <nUnCompressedDataLen> or 0 on error
*/
HB_FUNC( HB_UNCOMPRESSLEN )
{
ULONG ulLen = hb_parclen( 1 );
hb_retnint( ulLen ? hb_zlibUncompressedSize( hb_parc( 1 ), ulLen ) : 0 );
}
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