Function zstd_sys::ZSTD_estimateCStreamSize

pub unsafe extern "C" fn ZSTD_estimateCStreamSize(
    maxCompressionLevel: c_int,
) -> usize

ZSTD_estimateCStreamSize() : ZSTD_estimateCStreamSize() will provide a memory budget large enough for streaming compression using any compression level up to the max specified one. It will also consider src size to be arbitrarily “large”, which is a worst case scenario. If srcSize is known to always be small, ZSTD_estimateCStreamSize_usingCParams() can provide a tighter estimation. ZSTD_estimateCStreamSize_usingCParams() can be used in tandem with ZSTD_getCParams() to create cParams from compressionLevel. ZSTD_estimateCStreamSize_usingCCtxParams() can be used in tandem with ZSTD_CCtxParams_setParameter(). Only single-threaded compression is supported. This function will return an error code if ZSTD_c_nbWorkers is >= 1. Note : CStream size estimation is only correct for single-threaded compression. ZSTD_estimateCStreamSize_usingCCtxParams() will return an error code if ZSTD_c_nbWorkers is >= 1. Note 2 : ZSTD_estimateCStreamSize* functions are not compatible with the Block-Level Sequence Producer API at this time. Size estimates assume that no external sequence producer is registered.

ZSTD_DStream memory budget depends on frame’s window Size. This information can be passed manually, using ZSTD_estimateDStreamSize, or deducted from a valid frame Header, using ZSTD_estimateDStreamSize_fromFrame(); Any frame requesting a window size larger than max specified one will be rejected. Note : if streaming is init with function ZSTD_init?Stream_usingDict(), an internal ?Dict will be created, which additional size is not estimated here. In this case, get total size by adding ZSTD_estimate?DictSize