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<tr><td width=20><td><b>FLATE(3)</b><td align=right><b>FLATE(3)</b>
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<p><font size=+1><b>NAME </b></font><br>
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deflateinit, deflate, deflatezlib, deflateblock, deflatezlibblock,
inflateinit, inflate, inflatezlib, inflateblock, inflatezlibblock,
flateerr, mkcrctab, blockcrc, adler32 &ndash; deflate compression<br>
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<p><font size=+1><b>SYNOPSIS </b></font><br>
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<tt><font size=+1>#include &lt;u.h&gt;<br>
#include &lt;libc.h&gt;<br>
#include &lt;flate.h&gt;
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<tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;deflateinit(void)
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<tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;deflate(void *wr, int (*w)(void*,void*,int),<br>
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void *rr, int (*r)(void*,void*,int),<br>
int level, int debug)
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<tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;deflatezlib(void *wr, int (*w)(void*,void*,int),<br>
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void *rr, int (*r)(void*,void*,int),<br>
int level, int debug)
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<tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;deflateblock(uchar *dst, int dsize,<br>
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uchar *src, int ssize,<br>
int level, int debug)
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<tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;deflatezlibblock(uchar *dst, int dsize,<br>
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uchar *src, int ssize,<br>
int level, int debug)
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<tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;inflateinit(void)
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<tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;inflate(void *wr, int (*w)(void*, void*, int),<br>
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void *getr, int (*get)(void*))
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<tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;inflatezlib(void *wr, int (*w)(void*, void*, int),<br>
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void *getr, int (*get)(void*))
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<tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;inflateblock(uchar *dst, int dsize,<br>
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uchar *src, int ssize)
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<tt><font size=+1>int &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;inflatezlibblock(uchar *dst, int dsize,<br>
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uchar *src, int ssize)
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<tt><font size=+1>char &nbsp;&nbsp;&nbsp;&nbsp;*flateerr(int error)
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<tt><font size=+1>ulong &nbsp;&nbsp;&nbsp;*mkcrctab(ulong poly)
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<tt><font size=+1>ulong &nbsp;&nbsp;&nbsp;blockcrc(ulong *tab, ulong crc, void *buf, int n)
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<tt><font size=+1>ulong &nbsp;&nbsp;&nbsp;adler32(ulong adler, void *buf, int n)<br>
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<p><font size=+1><b>DESCRIPTION </b></font><br>
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These routines compress and decompress data using the deflate
compression algorithm, which is used for most gzip, zip, and zlib
files.
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<i>Deflate</i> compresses input data retrieved by calls to <i>r</i> with arguments
<i>rr</i>, an input buffer, and a count of bytes to read. <i>R</i> should return
the number of bytes read; end of input is signaled by returning
zero, an input error by returning a negative number. The compressed
output is written to <i>w</i> with arguments <i>wr</i>, the
output data, and the number of bytes to write. <i>W</i> should return
the number of bytes written; writing fewer than the requested
number of bytes is an error. <i>Level</i> indicates the amount of computation
deflate should do while compressing the data. Higher <i>levels</i> usually
take more time and produce smaller outputs. Valid
values are 1 to 9, inclusive; 6 is a good compromise. If <i>debug</i>
is non-zero, cryptic debugging information is produced on standard
error.
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<i>Inflate</i> reverses the process, converting compressed data into
uncompressed output. Input is retrieved one byte at a time by
calling <i>get</i> with the argument <i>getr</i>. End of input of signaled by
returning a negative value. The uncompressed output is written
to <i>w</i>, which has the same interface as for <i>deflate</i>.
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<i>Deflateblock</i> and <i>inflateblock</i> operate on blocks of memory but
are otherwise similar to <i>deflate</i> and <i>inflate</i>.
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The zlib functions are similar, but operate on files with a zlib
header and trailer.
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<i>Deflateinit</i> or <i>inflateinit</i> must be called once before any call
to the corresponding routines.
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If the above routines fail, they return a negative number indicating
the problem. The possible values are <i>FlateNoMem</i>, <i>FlateInputFail</i>,
<i>FlateOutputFail</i>, <i>FlateCorrupted</i>, and <i>FlateInternal</i>. <i>Flateerr</i> converts
the number into a printable message. <i>FlateOk</i> is defined to be
zero, the successful return value for <i>deflateinit</i>,
<i>deflate</i>, <i>deflatezlib</i>, <i>inflateinit</i>, <i>inflate</i>, and <i>inflatezlib</i>. The
block functions return the number of bytes produced when they
succeed.
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<i>Mkcrctab</i> allocates (using <a href="../man3/malloc.html"><i>malloc</i>(3)</a>), initializes, and returns
a table for rapid computation of 32 bit CRC values using the polynomial
<i>poly</i>. <i>Blockcrc</i> uses <i>tab</i>, a table returned by <i>mkcrctab</i>, to update
<i>crc</i> for the <i>n</i> bytes of data in <i>buf</i>, and returns the new value.
<i>Crc</i> should initially be zero. <i>Blockcrc</i> pre-conditions and
post-conditions <i>crc</i> by ones complementation.
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<i>Adler32</i> updates the Adler 32-bit checksum of the <i>n</i> butes of data
in <i>buf.</i> The initial value of <i>adler</i> (that is, its value after seeing
zero bytes) should be 1.<br>
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<p><font size=+1><b>SOURCE </b></font><br>
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<tt><font size=+1>/usr/local/plan9/src/libflate<br>
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