SCZ - Streams

https://sourceforge.net/projects/scz-compress/ July 24, 2005

The core SCZ routines enable whole files or buffers to be compressed or decompressed. However, this may be inconvenient when data is prepared or consumed incrementally. The following routines, found in scz_streams.c, offer alternative methods for accessing SCZ compression incrementally, by individual lines or XML tags, instead of whole file buffers. They enable ".scz" files to be opened for writing or reading, followed by many character-string-line reads/writes, or XML-tag reads/writes, and finally closed. They operate much like fopen, feof, fgets, fputs, and fclose. The SCZ equivalents are:

Scz_File_Open( filename, mode );
Scz_Feof( sczfile );
Scz_ReadString( sczfile, delimiter, outstring, maxN );
Scz_WriteString( sczfile, string, N );
Scz_File_Close( sczfile );

Examples can be found in the SCZ streams-tests package. The formal definitions are provided below:

Scz_File_Open( filename, mode ) - Open a file for reading or writing compressed data. First argument is file-name. Second argument is 'r' or 'w'. Returns 0 on failure to open file.
struct SCZ_File *Scz_File_Open( char *filename, char *mode );
Scz_Feof( sczfile ) - Test for end of a compressed input file. Returns 1 (boolean true) if file being read has reached the end, otherwise returns 0 (boolean false).
int Scz_Feof( struct SCZ_File *sczfile );
Scz_ReadString( sczfile, delimiter, outstring, maxN ) - Incrementally reads compressed file, decompresses and returns the next line, xml-tag or xml-contents. This routine is handy for applications wishing to read compressed data directly from disk and to uncompress the input directly while reading from the disk. First argument is SCZ_File pointer, as returned by Scz_File_Open(). Second argument is the delimiter list. To return input by carriage-return delineated lines, use "\n", to parse by XML tags, use "<>". (Delimiters "<>" will be left in the returned tags. If a returned string in XML-mode is not surrounded by "<>", then it is content data from between XML tags; not a tag.) Third argument is null-terminated output character string, which must be pre-allocated. This routine does not allocate the output string! Forth parameter is the maximum length of returned strings, IE. the length of the supplied output array.
int Scz_ReadString( struct SCZ_File *sczfile, char *delimiter, unsigned char *outbuffer, int maxN );
Scz_WriteString( sczfile, string, N ) - Incrementally buffers data and compresses it to an output file when appropriate. This routine is handy for applications wishing to compress output while writing to disk. Especially those creating only small amounts of data at a time. First argument is SCZ_File pointer, as returned by Scz_File_Open(). Second argument is input array, third is the array's length.
This routine just adds to an scz buffer, until enough has accumulated to compress a block's worth. After all writing is done, file must be closed with Scz_File_Close().
int Scz_WriteString( struct SCZ_File *sczfile, unsigned char *buffer, int N );
Scz_File_Close( sczfile ) - Close a file after reading or writing compressed data. Argument is scz_file to be closed. If the file is open for writing, this routines finishes compressing and flushes any unwritten data to the file.
void *Scz_File_Close( struct SCZ_File *sczfile );

Note: The scz_compress_lib.c and scz_decompress_lib.c must be included in the compiled file when using the scz_streams.c routines. For convenience, commented-out include statements at the top of scz_streams.c can be uncommented, if not included elsewhere.