78 lines
1.8 KiB
C
78 lines
1.8 KiB
C
/**
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* \file lzma/delta.h
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* \brief Delta filter
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*/
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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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* See ../lzma.h for information about liblzma as a whole.
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*/
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#ifndef LZMA_H_INTERNAL
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# error Never include this file directly. Use <lzma.h> instead.
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#endif
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/**
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* \brief Filter ID
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*
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* Filter ID of the Delta filter. This is used as lzma_filter.id.
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*/
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#define LZMA_FILTER_DELTA LZMA_VLI_C(0x03)
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/**
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* \brief Type of the delta calculation
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*
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* Currently only byte-wise delta is supported. Other possible types could
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* be, for example, delta of 16/32/64-bit little/big endian integers, but
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* these are not currently planned since byte-wise delta is almost as good.
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*/
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typedef enum {
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LZMA_DELTA_TYPE_BYTE
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} lzma_delta_type;
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/**
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* \brief Options for the Delta filter
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*
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* These options are needed by both encoder and decoder.
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*/
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typedef struct {
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/** For now, this must always be LZMA_DELTA_TYPE_BYTE. */
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lzma_delta_type type;
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/**
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* \brief Delta distance
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*
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* With the only currently supported type, LZMA_DELTA_TYPE_BYTE,
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* the distance is as bytes.
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*
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* Examples:
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* - 16-bit stereo audio: distance = 4 bytes
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* - 24-bit RGB image data: distance = 3 bytes
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*/
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uint32_t dist;
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# define LZMA_DELTA_DIST_MIN 1
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# define LZMA_DELTA_DIST_MAX 256
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/*
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* Reserved space to allow possible future extensions without
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* breaking the ABI. You should not touch these, because the names
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* of these variables may change. These are and will never be used
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* when type is LZMA_DELTA_TYPE_BYTE, so it is safe to leave these
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* uninitialized.
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*/
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uint32_t reserved_int1;
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uint32_t reserved_int2;
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uint32_t reserved_int3;
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uint32_t reserved_int4;
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void *reserved_ptr1;
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void *reserved_ptr2;
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} lzma_options_delta;
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