kopia lustrzana https://github.com/micropython/micropython
67 wiersze
1.8 KiB
C
67 wiersze
1.8 KiB
C
/*
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* uzlib - tiny deflate/inflate library (deflate, gzip, zlib)
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*
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* Copyright (c) 2003 by Joergen Ibsen / Jibz
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* All Rights Reserved
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*
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* http://www.ibsensoftware.com/
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*
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* Copyright (c) 2014-2018 by Paul Sokolovsky
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*
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* This software is provided 'as-is', without any express
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* or implied warranty. In no event will the authors be
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* held liable for any damages arising from the use of
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* this software.
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*
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* Permission is granted to anyone to use this software
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* for any purpose, including commercial applications,
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* and to alter it and redistribute it freely, subject to
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* the following restrictions:
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*
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* 1. The origin of this software must not be
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* misrepresented; you must not claim that you
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* wrote the original software. If you use this
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* software in a product, an acknowledgment in
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* the product documentation would be appreciated
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* but is not required.
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*
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* 2. Altered source versions must be plainly marked
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* as such, and must not be misrepresented as
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* being the original software.
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*
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* 3. This notice may not be removed or altered from
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* any source distribution.
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*/
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#include "tinf.h"
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int uzlib_zlib_parse_header(TINF_DATA *d)
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{
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unsigned char cmf, flg;
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/* -- get header bytes -- */
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cmf = uzlib_get_byte(d);
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flg = uzlib_get_byte(d);
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/* -- check format -- */
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/* check checksum */
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if ((256*cmf + flg) % 31) return TINF_DATA_ERROR;
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/* check method is deflate */
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if ((cmf & 0x0f) != 8) return TINF_DATA_ERROR;
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/* check window size is valid */
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if ((cmf >> 4) > 7) return TINF_DATA_ERROR;
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/* check there is no preset dictionary */
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if (flg & 0x20) return TINF_DATA_ERROR;
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/* initialize for adler32 checksum */
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d->checksum_type = TINF_CHKSUM_ADLER;
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d->checksum = 1;
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return cmf >> 4;
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}
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