PHP Manual: deflate

function deflate_add(DeflateContext $context, string $data, int $flush_mode = ZLIB_SYNC_FLUSH): string|false

Incrementally deflates data in the specified context.

context: A context created with deflate_init().
data: A chunk of data to compress.
flush_mode: One of ZLIB_BLOCK, ZLIB_NO_FLUSH, ZLIB_PARTIAL_FLUSH, ZLIB_SYNC_FLUSH (default), ZLIB_FULL_FLUSH, ZLIB_FINISH. Normally you will want to set ZLIB_NO_FLUSH to maximize compression, and ZLIB_FINISH to terminate with the last chunk of data. See the » zlib manual for a detailed description of these constants.

Returns a chunk of compressed data, or false on failure.

If invalid arguments are given, an error of level E_WARNING is generated.

Version	Description
8.0.0	`context` expects a DeflateContext instance now; previously, a resource was expected.

deflate_add