Copyright	(c) 2016-present Facebook Inc. All rights reserved.
License	BSD3
Maintainer	bryano@fb.com
Stability	experimental
Portability	GHC
Safe Haskell	None
Language	Haskell2010

Codec.Compression.Zstd.Base

Contents

One-shot functions
- Cheaper operations using contexts
  - Compression
  - Decompression
Streaming operations
Dictionary compression
- Pre-digested dictionaries
  - Compression
  - Decompression

Description

Mid-level bindings to the native zstd compression library. These bindings provide a little more safety and ease of use than the lowest-level FFI bindings. Unless you have highly specialized needs, you should use the streaming or other higher-level APIs instead.

Synopsis

compress :: Ptr dst -> Int -> Ptr src -> Int -> Int -> IO (Either String Int)
maxCLevel :: Int
decompress :: Ptr dst -> Int -> Ptr src -> Int -> IO (Either String Int)
getDecompressedSize :: Ptr src -> Int -> IO (Maybe Word64)
data CCtx
withCCtx :: (Ptr CCtx -> IO a) -> IO a
compressCCtx :: Ptr CCtx -> Ptr dst -> Int -> Ptr src -> CSize -> Int -> IO (Either String Int)
data DCtx
withDCtx :: (Ptr DCtx -> IO a) -> IO a
decompressDCtx :: Ptr DCtx -> Ptr dst -> Int -> Ptr src -> Int -> IO (Either String Int)
data CStream
data DStream
data Buffer io = forall a. Buffer {
- bufPtr :: !(Ptr a)
- bufSize :: !CSize
- bufPos :: !CSize
}
data In
data Out
cstreamInSize :: Int
cstreamOutSize :: Int
createCStream :: IO CStream
initCStream :: CStream -> Int -> IO (Either String ())
compressStream :: CStream -> Ptr (Buffer Out) -> Ptr (Buffer In) -> IO (Either String Int)
endStream :: CStream -> Ptr (Buffer Out) -> IO (Either String Int)
dstreamInSize :: Int
dstreamOutSize :: Int
createDStream :: IO DStream
initDStream :: DStream -> IO (Either String ())
decompressStream :: DStream -> Ptr (Buffer Out) -> Ptr (Buffer In) -> IO (Either String Int)
trainFromBuffer :: Ptr dict -> Int -> Ptr samples -> Ptr Int -> Int -> IO (Either String Int)
getDictID :: Ptr dict -> Int -> IO (Maybe Word)
compressUsingDict :: Ptr CCtx -> Ptr dst -> Int -> Ptr src -> Int -> Ptr dict -> Int -> Int -> IO (Either String Int)
decompressUsingDict :: Ptr DCtx -> Ptr dst -> Int -> Ptr src -> Int -> Ptr dict -> Int -> IO (Either String Int)
data CDict
createCDict :: Ptr dict -> Int -> Int -> IO CDict
compressUsingCDict :: Ptr CCtx -> Ptr dst -> Int -> Ptr src -> Int -> CDict -> IO (Either String Int)
data DDict
createDDict :: Ptr dict -> Int -> IO DDict
decompressUsingDDict :: Ptr DCtx -> Ptr dst -> Int -> Ptr src -> Int -> DDict -> IO (Either String Int)

One-shot functions

compress Source #

Arguments

:: Ptr dst	Destination buffer.
-> Int	Capacity of destination buffer.
-> Ptr src	Source buffer.
-> Int	Size of source buffer.
-> Int	Compression level.
-> IO (Either String Int)

Compress bytes from source buffer into destination buffer. The destination buffer must be already allocated.

Returns the number of bytes written into destination buffer, or an error description if it fails.

maxCLevel :: Int Source #

The maximum compression level supported by the library.

decompress Source #

Arguments

:: Ptr dst	Destination buffer.
-> Int	Capacity of destination buffer.
-> Ptr src	Source buffer.
-> Int	Size of compressed input. This must be exact, so for example supplying the size of a buffer that is larger than the compressed input will cause a failure.
-> IO (Either String Int)

Decompress a buffer. The destination buffer must be already allocated.

Returns the number of bytes written into destination buffer, or an error description if it fails.

getDecompressedSize :: Ptr src -> Int -> IO (Maybe Word64) Source #

Returns the decompressed size of a compressed payload if known.

To discover precisely why a result is not known, follow up with getFrameParams.

Cheaper operations using contexts

Compression

data CCtx Source #

An opaque compression context structure.

withCCtx :: (Ptr CCtx -> IO a) -> IO a Source #

Allocate a compression context, run an action that may reuse the context as many times as it needs, then free the context.

compressCCtx Source #

Arguments

:: Ptr CCtx	Compression context.
-> Ptr dst	Destination buffer.
-> Int	Capacity of destination buffer.
-> Ptr src	Source buffer.
-> CSize	Size of source buffer.
-> Int	Compression level.
-> IO (Either String Int)

Compress bytes from source buffer into destination buffer. The destination buffer must be already allocated.

Returns the number of bytes written into destination buffer, or an error description if it fails.

Decompression

data DCtx Source #

An opaque decompression context structure.

withDCtx :: (Ptr DCtx -> IO a) -> IO a Source #

Allocate a decompression context, run an action that may reuse the context as many times as it needs, then free the context.

decompressDCtx Source #

Arguments

:: Ptr DCtx	Decompression context.
-> Ptr dst	Destination buffer.
-> Int	Capacity of destination buffer.
-> Ptr src	Source buffer.
-> Int	Size of compressed input. This must be exact, so for example supplying the size of a buffer that is larger than the compressed input will cause a failure.
-> IO (Either String Int)

Decompress a buffer. The destination buffer must be already allocated.

Returns the number of bytes written into destination buffer, or an error description if it fails.

Streaming operations

Streaming types

data CStream Source #

A context for streaming compression.

data DStream Source #

A context for streaming decompression.

data Buffer io Source #

A streaming buffer type. The type parameter statically indicates whether the buffer is used to track an input or output buffer.

Constructors

forall a. Buffer

Fields

bufPtr :: !(Ptr a)
Pointer to the start of the buffer. This can be set once by the caller, and read by the streaming function.
bufSize :: !CSize
Size of the buffer (in bytes). This can be set once by the caller, and is read by the streaming function.
bufPos :: !CSize
Current offset into the buffer (in bytes). This must be initially set to zero by the caller, and is updated by the streaming function.

Instances

Instances details

Storable (Buffer io) Source #

Instance details

Defined in Codec.Compression.Zstd.FFI.Types

Methods

sizeOf :: Buffer io -> Int #

alignment :: Buffer io -> Int #

peekElemOff :: Ptr (Buffer io) -> Int -> IO (Buffer io) #

pokeElemOff :: Ptr (Buffer io) -> Int -> Buffer io -> IO () #

peekByteOff :: Ptr b -> Int -> IO (Buffer io) #

pokeByteOff :: Ptr b -> Int -> Buffer io -> IO () #

peek :: Ptr (Buffer io) -> IO (Buffer io) #

poke :: Ptr (Buffer io) -> Buffer io -> IO () #

data In Source #

A tag type to indicate that a Buffer is used for tracking input.

data Out Source #

A tag type to indicate that a Buffer is used for tracking output.

Streaming compression

cstreamInSize :: Int Source #

Recommended size for input buffer.

cstreamOutSize :: Int Source #

Recommended size for output buffer.

createCStream :: IO CStream Source #

Create a CStream value. After use, this will eventually be freed via a finalizer.

initCStream Source #

Arguments

:: CStream
-> Int	Compression level.
-> IO (Either String ())

Begin a new streaming compression operation.

compressStream :: CStream -> Ptr (Buffer Out) -> Ptr (Buffer In) -> IO (Either String Int) Source #

Consume part or all of an input.

endStream :: CStream -> Ptr (Buffer Out) -> IO (Either String Int) Source #

End a compression stream. This performs a flush and writes a frame epilogue.

Streaming decompression

dstreamInSize :: Int Source #

Recommended size for input buffer.

dstreamOutSize :: Int Source #

Recommended size for output buffer.

createDStream :: IO DStream Source #

Create a streaming decompression context. After use, this will eventually be freed via a finalizer.

initDStream :: DStream -> IO (Either String ()) Source #

Begin a new streaming decompression operation.

decompressStream :: DStream -> Ptr (Buffer Out) -> Ptr (Buffer In) -> IO (Either String Int) Source #

Consume part or all of an input.

Dictionary compression

trainFromBuffer Source #

Arguments

:: Ptr dict	Preallocated dictionary buffer.
-> Int	Capacity of dictionary buffer.
-> Ptr samples	Concatenated samples.
-> Ptr Int	Array of sizes of samples.
-> Int	Number of samples.
-> IO (Either String Int)

Train a dictionary from a collection of samples. Returns the number size of the resulting dictionary.

getDictID :: Ptr dict -> Int -> IO (Maybe Word) Source #

Return the identifier for the given dictionary, or Nothing if not a valid dictionary.

compressUsingDict Source #

Arguments

:: Ptr CCtx
-> Ptr dst	Destination buffer.
-> Int	Capacity of destination buffer.
-> Ptr src	Source buffer.
-> Int	Size of source buffer.
-> Ptr dict	Dictionary.
-> Int	Size of dictionary.
-> Int	Compression level.
-> IO (Either String Int)

Compress bytes from source buffer into destination buffer. The destination buffer must be already allocated.

Returns the number of bytes written into destination buffer, or an error description if it fails.

decompressUsingDict Source #

Arguments

:: Ptr DCtx
-> Ptr dst	Destination buffer.
-> Int	Capacity of destination buffer.
-> Ptr src	Source buffer.
-> Int	Size of compressed input. This must be exact, so for example supplying the size of a buffer that is larger than the compressed input will cause a failure.
-> Ptr dict	Dictionary.
-> Int	Size of dictionary.
-> IO (Either String Int)

Decompress a buffer. The destination buffer must be already allocated.

Returns the number of bytes written into destination buffer, or an error description if it fails.

Pre-digested dictionaries

Compression

data CDict Source #

A pre-digested compression dictionary.

createCDict Source #

Arguments

:: Ptr dict	Dictionary.
-> Int	Size of dictionary.
-> Int	Compression level.
-> IO CDict

Create a pre-digested compression dictionary. After use, this will eventually be freed via a finalizer.

compressUsingCDict Source #

Arguments

:: Ptr CCtx	Compression context.
-> Ptr dst	Destination buffer.
-> Int	Capacity of destination buffer.
-> Ptr src	Source buffer.
-> Int	Size of source buffer.
-> CDict	Dictionary.
-> IO (Either String Int)

Compress bytes from source buffer into destination buffer, using a pre-digested dictionary. The destination buffer must be already allocated.

Returns the number of bytes written into destination buffer, or an error description if it fails.

Decompression

data DDict Source #

A pre-digested decompression dictionary.

createDDict Source #

Arguments

:: Ptr dict	Dictionary.
-> Int	Size of dictionary.
-> IO DDict

Create a pre-digested decompression dictionary. After use, this will eventually be freed via a finalizer.

decompressUsingDDict Source #

Arguments

:: Ptr DCtx	Compression context.
-> Ptr dst	Destination buffer.
-> Int	Capacity of destination buffer.
-> Ptr src	Source buffer.
-> Int	Size of source buffer.
-> DDict	Dictionary.
-> IO (Either String Int)

Decompress bytes from source buffer into destination buffer, using a pre-digested dictionary. The destination buffer must be already allocated.

Returns the number of bytes written into destination buffer, or an error description if it fails.