 | zlib-bindings-0.0.0: Low-level bindings to the zlib package. | Contents | Index |
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| Description |
This is a middle-level wrapper around the zlib C API. It allows you to
work fully with bytestrings and not touch the FFI at all, but is still
low-level enough to allow you to implement high-level abstractions such as
enumerators. Significantly, it does not use lazy IO.
You'll probably need to reference the docs a bit to understand the
WindowBits parameters below, but a basic rule of thumb is 15 is for zlib
compression, and 31 for gzip compression.
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| Synopsis |
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| Inflate
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| data Inflate |
| The state of an inflation (eg, decompression) process. All allocated
memory is automatically reclaimed by the garbage collector.
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| initInflate :: WindowBits -> IO Inflate |
| Initialize an inflation process with the given WindowBits. You will need
to call withInflateInput to feed compressed data to this and
finishInflate to extract the final chunk of decompressed data.
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| withInflateInput :: Inflate -> ByteString -> (IO (Maybe ByteString) -> IO a) -> IO a |
Feed the given ByteString to the inflater. This function takes a
function argument which takes a "popper". A popper is an IO action that
will return the next bit of inflated data, returning Nothing when there is
no more data to be popped.
Note that this function automatically buffers the output to
defaultChunkSize, and therefore you won't get any data from the popper
until that much decompressed data is available. After you have fed all of
the compressed data to this function, you can extract your final chunk of
decompressed data using finishInflate.
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| finishInflate :: Inflate -> IO ByteString |
| As explained in withInflateInput, inflation buffers your decompressed
data. After you call withInflateInput with your last chunk of compressed
data, you will likely have some data still sitting in the buffer. This
function will return it to you.
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| Deflate
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| data Deflate |
| The state of a deflation (eg, compression) process. All allocated memory
is automatically reclaimed by the garbage collector.
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| initDeflate |
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| withDeflateInput :: Deflate -> ByteString -> (IO (Maybe ByteString) -> IO a) -> IO a |
Feed the given ByteString to the deflater. This function takes a
function argument which takes a "popper". A popper is an IO action that
will return the next bit of deflated data, returning Nothing when there is
no more data to be popped.
Note that this function automatically buffers the output to
defaultChunkSize, and therefore you won't get any data from the popper
until that much compressed data is available. After you have fed all of the
decompressed data to this function, you can extract your final chunks of
compressed data using finishDeflate.
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| finishDeflate :: Deflate -> (IO (Maybe ByteString) -> IO a) -> IO a |
| As explained in withDeflateInput, deflation buffers your compressed
data. After you call withDeflateInput with your last chunk of decompressed
data, we need to flush the rest of the data waiting to be deflated. This
function takes a function parameter which accepts a "popper", just like
withDeflateInput.
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| Data types
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| data WindowBits |
This specifies the size of the compression window. Larger values of this
parameter result in better compression at the expense of higher memory
usage.
The compression window size is the value of the the window bits raised to
the power 2. The window bits must be in the range 8..15 which corresponds
to compression window sizes of 256b to 32Kb. The default is 15 which is also
the maximum size.
The total amount of memory used depends on the window bits and the
MemoryLevel. See the MemoryLevel for the details.
| | Constructors | |
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| defaultWindowBits :: WindowBits |
| The default WindowBits is 15 which is also the maximum size.
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| data ZlibException |
Exception that can be thrown from the FFI code. The parameter is the
numerical error code from the zlib library. Quoting the zlib.h file
directly:
- #define Z_OK 0
- #define Z_STREAM_END 1
- #define Z_NEED_DICT 2
- #define Z_ERRNO (-1)
- #define Z_STREAM_ERROR (-2)
- #define Z_DATA_ERROR (-3)
- #define Z_MEM_ERROR (-4)
- #define Z_BUF_ERROR (-5)
- #define Z_VERSION_ERROR (-6)
| | Constructors | |  Instances | |
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