external/public-domain/xz/dist/src/liblzma/api/lzma/delta.h

   1 /**
   2  * \file        lzma/delta.h
   3  * \brief       Delta filter
   4  */
   5
   6 /*
   7  * Author: Lasse Collin
   8  *
   9  * This file has been put into the public domain.
  10  * You can do whatever you want with this file.
  11  *
  12  * See ../lzma.h for information about liblzma as a whole.
  13  */
  14
  15 #ifndef LZMA_H_INTERNAL
  16 #       error Never include this file directly. Use <lzma.h> instead.
  17 #endif
  18
  19
  20 /**
  21  * \brief       Filter ID
  22  *
  23  * Filter ID of the Delta filter. This is used as lzma_filter.id.
  24  */
  25 #define LZMA_FILTER_DELTA       LZMA_VLI_C(0x03)
  26
  27
  28 /**
  29  * \brief       Type of the delta calculation
  30  *
  31  * Currently only byte-wise delta is supported. Other possible types could
  32  * be, for example, delta of 16/32/64-bit little/big endian integers, but
  33  * these are not currently planned since byte-wise delta is almost as good.
  34  */
  35 typedef enum {
  36         LZMA_DELTA_TYPE_BYTE
  37 } lzma_delta_type;
  38
  39
  40 /**
  41  * \brief       Options for the Delta filter
  42  *
  43  * These options are needed by both encoder and decoder.
  44  */
  45 typedef struct {
  46         /** For now, this must always be LZMA_DELTA_TYPE_BYTE. */
  47         lzma_delta_type type;
  48
  49         /**
  50          * \brief       Delta distance
  51          *
  52          * With the only currently supported type, LZMA_DELTA_TYPE_BYTE,
  53          * the distance is as bytes.
  54          *
  55          * Examples:
  56          *  - 16-bit stereo audio: distance = 4 bytes
  57          *  - 24-bit RGB image data: distance = 3 bytes
  58          */
  59         uint32_t dist;
  60 #       define LZMA_DELTA_DIST_MIN 1
  61 #       define LZMA_DELTA_DIST_MAX 256
  62
  63         /*
  64          * Reserved space to allow possible future extensions without
  65          * breaking the ABI. You should not touch these, because the names
  66          * of these variables may change. These are and will never be used
  67          * when type is LZMA_DELTA_TYPE_BYTE, so it is safe to leave these
  68          * uninitialized.
  69          */
  70         uint32_t reserved_int1;
  71         uint32_t reserved_int2;
  72         uint32_t reserved_int3;
  73         uint32_t reserved_int4;
  74         void *reserved_ptr1;
  75         void *reserved_ptr2;
  76
  77 } lzma_options_delta;