Method Gz.compress()
- Method compress
string(8bit) compress(string(8bit) data, void|bool raw, void|int(0..9) level, void|int strategy, void|int(8..15) window_size)
- Description
Encodes and returns the input data according to the deflate format defined in RFC 1951.
- Parameter data
The data to be encoded.
- Parameter raw
If set, the data is encoded without the header and footer defined in RFC 1950. Example of uses is the ZIP container format.
- Parameter level
Indicates the level of effort spent to make the data compress well. Zero means no packing, 2-3 is considered 'fast', 6 is default and higher is considered 'slow' but gives better packing.
- Parameter strategy
The strategy to be used when compressing the data. One of the following.
DEFAULT_STRATEGY The default strategy as selected in the zlib library.
FILTERED This strategy is intented for data created by a filter or predictor and will put more emphasis on huffman encoding and less on LZ string matching. This is between DEFAULT_STRATEGY and HUFFMAN_ONLY.
RLE This strategy is even closer to the HUFFMAN_ONLY in that it only looks at the latest byte in the window, i.e. a window size of 1 byte is sufficient for decompression. This mode is not available in all zlib versions.
HUFFMAN_ONLY This strategy will turn of string matching completely, only doing huffman encoding. Window size doesn't matter in this mode and the data can be decompressed with a zero size window.
FIXED In this mode dynamic huffman codes are disabled, allowing for a simpler decoder for special applications. This mode is not available in all zlib versions.
- Parameter window_size
Defines the size of the LZ77 window from 256 bytes to 32768 bytes, expressed as 2^x.
- See also