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///////////////////////////////////////////////////////////////////////////////
//
/// \file delta_decoder.c
/// \brief Delta filter decoder
//
// Author: Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "delta_decoder.h"
#include "delta_private.h"
static void
decode_buffer(lzma_delta_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(void *coder_ptr, const 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)
{
lzma_delta_coder *coder = coder_ptr;
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);
// out might be NULL. In that case size == 0. Null pointer + 0 is
// undefined behavior so skip the call in that case as it would
// do nothing anyway.
const size_t size = *out_pos - out_start;
if (size > 0)
decode_buffer(coder, out + out_start, size);
return ret;
}
extern lzma_ret
lzma_delta_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
const lzma_filter_info *filters)
{
next->code = &delta_decode;
return lzma_delta_coder_init(next, allocator, filters);
}
extern lzma_ret
lzma_delta_props_decode(void **options, const lzma_allocator *allocator,
const uint8_t *props, size_t props_size)
{
if (props_size != 1)
return LZMA_OPTIONS_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->dist = props[0] + 1U;
*options = opt;
return LZMA_OK;
}
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