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