# Missing and Unimplemented Features

This document attempts to capture features of the zstd C API that are currently not exposed to Python.

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## Missing Constants

- `ZSTD_CLEVEL_DEFAULT`

- `ZSTD_SRCSIZEHINT_MIN`

- `ZSTD_SRCSIZEHINT_MAX`

- `ZSTD_BLOCKSIZE_MAX_MIN`

- `ZSTD_DECOMPRESSION_MARGIN`

## Compression and Decompression Parameters

- `ZSTD_p_forceAttachDict`

- `ZSTD_dictForceLoad`

- `ZSTD_c_targetCBlockSize`

- `ZSTD_c_literalCompressionMode`

- `ZSTD_c_srcSizeHint`

- `ZSTD_d_stableOutBuffer`

- `ZSTD_c_enableDedicatedDictSearch`

- `ZSTD_c_stableInBuffer`

- `ZSTD_c_stableOutBuffer`

- `ZSTD_c_blockDelimiters`

- `ZSTD_c_validateSequences`

- `ZSTD_c_useBlockSplitter`

- `ZSTD_c_useRowMatchFinder`

- `ZSTD_d_forceIgnoreChecksum`

- `ZSTD_d_refMultipleDDicts`

- `ZSTD_refMultipleDDicts_e`

- `ZSTD_c_prefetchCDictTables`

- `ZSTD_c_enableSeqProducerFallback`

- `ZSTD_c_maxBlockSize`

- `ZSTD_c_searchForExternalRepcodes`

- `ZSTD_d_disableHuffmanAssembly`

- `ZSTD_d_stableOutBuffer`

## Missing Functions

- `ZSTDMT_toFlushNow()`

- `ZSTD_minCLevel()`

- `ZSTD_cParam_getBounds()`

- `ZSTD_dParam_getBounds()`

- `ZSTD_generateSequences()`

- `ZSTD_mergeBlockDelimiters()`

- `ZSTD_compressSequences()`

- `ZSTD_writeSkippableFrame()`

- `ZSTD_decompressionMargin()`

- `ZSTD_sequenceBound()`

## Missing Features

- `ZSTD_getFrameProgression()` isn’t exposed everywhere it could be.

- Compression parameters cannot be modified mid operation.

- `ZSTD_Sequence` and related `ZSTD_getSequences()` not exposed.

- `ZSTD_threadPool` not exposed.

- `ZSTD_sequenceProducer_F` and `ZSTD_registerSequenceProducer()` not exposed.

- `ZSTD_CCtx_getParameter()`, `ZSTD_CCtxParam_getParameter()`, and `ZSTD_DCtx_getParameter()` could be leveraged for parameter retrieval.

- `ZSTD_CCtx_setCParams()` could potentially be utilized.

- `ZSTD_error_*` constants / error codes not exposed.