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///////////////////////////////////////////////////////////////////////////////
//
/// \file delta_decoder.c
/// \brief Delta filter decoder
//
// Copyright (C) 2007, 2008 Lasse Collin
//
// 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 the License, or (at your option) any later version.
//
// This library 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.
//
///////////////////////////////////////////////////////////////////////////////
#include "delta_decoder.h"
#include "delta_common.h"
static void
decode_buffer(lzma_coder *coder, uint8_t *buffer, size_t size)
{
const size_t distance = coder->distance;
for (size_t i = 0; i < size; ++i) {
buffer[i] += coder->history[(distance + coder->pos) & 0xFF];
coder->history[coder->pos-- & 0xFF] = buffer[i];
}
}
static lzma_ret
delta_decode(lzma_coder *coder, lzma_allocator *allocator,
const uint8_t *restrict in, size_t *restrict in_pos,
size_t in_size, uint8_t *restrict out,
size_t *restrict out_pos, size_t out_size, lzma_action action)
{
assert(coder->next.code != NULL);
const size_t out_start = *out_pos;
const lzma_ret ret = coder->next.code(coder->next.coder, allocator,
in, in_pos, in_size, out, out_pos, out_size,
action);
decode_buffer(coder, out + out_start, *out_pos - out_start);
return ret;
}
extern lzma_ret
lzma_delta_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
const lzma_filter_info *filters)
{
return lzma_delta_coder_init(next, allocator, filters, &delta_decode);
}
extern lzma_ret
lzma_delta_props_decode(void **options, lzma_allocator *allocator,
const uint8_t *props, size_t props_size)
{
if (props_size != 1)
return LZMA_HEADER_ERROR;
lzma_options_delta *opt
= lzma_alloc(sizeof(lzma_options_delta), allocator);
if (opt == NULL)
return LZMA_MEM_ERROR;
opt->type = LZMA_DELTA_TYPE_BYTE;
opt->distance = props[0] + 1;
*options = opt;
return LZMA_OK;
}
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