mirror of https://git.tukaani.org/xz.git
83 lines
2.2 KiB
C
83 lines
2.2 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file delta_decoder.c
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/// \brief Delta filter decoder
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//
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// Copyright (C) 2007, 2008 Lasse Collin
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2.1 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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///////////////////////////////////////////////////////////////////////////////
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#include "delta_decoder.h"
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#include "delta_common.h"
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static void
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decode_buffer(lzma_coder *coder, uint8_t *buffer, size_t size)
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{
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const size_t distance = coder->distance;
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for (size_t i = 0; i < size; ++i) {
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buffer[i] += coder->history[(distance + coder->pos) & 0xFF];
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coder->history[coder->pos-- & 0xFF] = buffer[i];
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}
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}
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static lzma_ret
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delta_decode(lzma_coder *coder, lzma_allocator *allocator,
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const uint8_t *restrict in, size_t *restrict in_pos,
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size_t in_size, uint8_t *restrict out,
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size_t *restrict out_pos, size_t out_size, lzma_action action)
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{
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assert(coder->next.code != NULL);
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const size_t out_start = *out_pos;
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const lzma_ret ret = coder->next.code(coder->next.coder, allocator,
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in, in_pos, in_size, out, out_pos, out_size,
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action);
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decode_buffer(coder, out + out_start, *out_pos - out_start);
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return ret;
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}
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extern lzma_ret
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lzma_delta_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
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const lzma_filter_info *filters)
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{
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return lzma_delta_coder_init(next, allocator, filters, &delta_decode);
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}
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extern lzma_ret
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lzma_delta_props_decode(void **options, lzma_allocator *allocator,
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const uint8_t *props, size_t props_size)
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{
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if (props_size != 1)
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return LZMA_HEADER_ERROR;
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lzma_options_delta *opt
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= lzma_alloc(sizeof(lzma_options_delta), allocator);
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if (opt == NULL)
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return LZMA_MEM_ERROR;
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opt->type = LZMA_DELTA_TYPE_BYTE;
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opt->distance = props[0] + 1;
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*options = opt;
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return LZMA_OK;
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}
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