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///////////////////////////////////////////////////////////////////////////////
//
/// \file delta_common.c
/// \brief Common stuff for Delta encoder and decoder
//
// Author: Lasse Collin
//
// This file has been put into the public domain.
// You can do whatever you want with this file.
//
///////////////////////////////////////////////////////////////////////////////
#include "delta_common.h"
#include "delta_private.h"
static void
delta_coder_end(lzma_coder *coder, lzma_allocator *allocator)
{
lzma_next_end(&coder->next, allocator);
lzma_free(coder, allocator);
return;
}
extern lzma_ret
lzma_delta_coder_init(lzma_next_coder *next, lzma_allocator *allocator,
const lzma_filter_info *filters, lzma_code_function code)
{
// Allocate memory for the decoder if needed.
if (next->coder == NULL) {
next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
if (next->coder == NULL)
return LZMA_MEM_ERROR;
// End function is the same for encoder and decoder.
next->end = &delta_coder_end;
next->coder->next = LZMA_NEXT_CODER_INIT;
}
// Coding function is different for encoder and decoder.
next->code = code;
// Validate the options.
if (lzma_delta_coder_memusage(filters[0].options) == UINT64_MAX)
return LZMA_OPTIONS_ERROR;
// Set the delta distance.
const lzma_options_delta *opt = filters[0].options;
next->coder->distance = opt->dist;
// Initialize the rest of the variables.
next->coder->pos = 0;
memzero(next->coder->history, LZMA_DELTA_DIST_MAX);
// Initialize the next decoder in the chain, if any.
return lzma_next_filter_init(&next->coder->next,
allocator, filters + 1);
}
extern uint64_t
lzma_delta_coder_memusage(const void *options)
{
const lzma_options_delta *opt = options;
if (opt == NULL || opt->type != LZMA_DELTA_TYPE_BYTE
|| opt->dist < LZMA_DELTA_DIST_MIN
|| opt->dist > LZMA_DELTA_DIST_MAX)
return UINT64_MAX;
return sizeof(lzma_coder);
}
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