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Quelle Decompressor.cpp Sprache: C |
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/* GRAPHITE2 LICENSING
Copyright 2015, SIL International All rights reserved. This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should also have received a copy of the GNU Lesser General Public License along with this library in the file named "LICENSE". If not, write to the Free Software Foundation, 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA or visit their web page on the internet at http://www.fsf.org/licenses/lgpl.html. Alternatively, the contents of this file may be used under the terms of the Mozilla Public License (http://mozilla.org/MPL) or the GNU General Public License, as published by the Free Software Foundation, either version 2 of the License or (at your option) any later version. */ #include <cassert> #include "inc/Decompressor.h" #include "inc/Compression.h" using namespace lz4; namespace { inline u32 read_literal(u8 const * &s, u8 const * const e, u32 l) { if (l == 15 && s != e) { u8 b = 0; do { l += b = *s++; } while(b==0xff && s != e); } return l; } bool read_sequence(u8 const * &src, u8 const * const end, u8 const * &literal, u32 & literal_len, u32 & match_len, u32 & match_dist) { u8 const token = *src++; literal_len = read_literal(src, end, token >> 4); literal = src; src += literal_len; // Normal exit for end of stream, wrap arround check and parital match check. if (src > end - sizeof(u16) || src < literal) return false; match_dist = *src++; match_dist |= *src++ << 8; match_len = read_literal(src, end, token & 0xf) + MINMATCH; // Malformed stream check. return src <= end-MINCODA; } } int lz4::decompress(void const *in, size_t in_size, void *out, size_t out_size) { if (out_size <= in_size || in_size < MINSRCSIZE) return -1; u8 const * src = static_cast<u8 const *>(in), * literal = 0, * const src_end = src + in_size; u8 * dst = static_cast<u8*>(out), * const dst_end = dst + out_size; // Check the in and out size hasn't wrapped around. if (src >= src_end || dst >= dst_end) return -1; u32 literal_len = 0, match_len = 0, match_dist = 0; while (read_sequence(src, src_end, literal, literal_len, match_len, match_dist)) { if (literal_len != 0) { // Copy in literal. At this point the a minimal literal + minminal // match plus the coda (1 + 2 + 5) must be 8 bytes or more allowing // us to remain within the src buffer for an overrun_copy on // machines upto 64 bits. if (align(literal_len) > out_size) return -1; dst = overrun_copy(dst, literal, literal_len); out_size -= literal_len; } // Copy, possibly repeating, match from earlier in the // decoded output. u8 const * const pcpy = dst - match_dist; if (pcpy < static_cast<u8*>(out) || match_len > unsigned(out_size - LASTLITERALS) // Wrap around checks: || out_size < LASTLITERALS || pcpy >= dst) return -1; if (dst > pcpy+sizeof(unsigned long) && align(match_len) <= out_size) dst = overrun_copy(dst, pcpy, match_len); else dst = safe_copy(dst, pcpy, match_len); out_size -= match_len; } if (literal > src_end - literal_len || literal_len > out_size) return -1; dst = fast_copy(dst, literal, literal_len); return int(dst - (u8*)out); } ¤ Dauer der Verarbeitung: 0.16 Sekunden (vorverarbeitet) ¤*© Formatika GbR, Deutschland |
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2026-03-28