release/src-rt-6.x.4708/tools/misc/xz/src/liblzma/delta/delta_common.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       delta_common.c
   4 /// \brief      Common stuff for Delta encoder and decoder
   5 //
   6 //  Author:     Lasse Collin
   7 //
   8 //  This file has been put into the public domain.
   9 //  You can do whatever you want with this file.
  10 //
  11 ///////////////////////////////////////////////////////////////////////////////
  12
  13 #include "delta_common.h"
  14 #include "delta_private.h"
  15
  16
  17 static void
  18 delta_coder_end(lzma_coder *coder, lzma_allocator *allocator)
  19 {
  20         lzma_next_end(&coder->next, allocator);
  21         lzma_free(coder, allocator);
  22         return;
  23 }
  24
  25
  26 extern lzma_ret
  27 lzma_delta_coder_init(lzma_next_coder *next, lzma_allocator *allocator,
  28                 const lzma_filter_info *filters)
  29 {
  30         // Allocate memory for the decoder if needed.
  31         if (next->coder == NULL) {
  32                 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
  33                 if (next->coder == NULL)
  34                         return LZMA_MEM_ERROR;
  35
  36                 // End function is the same for encoder and decoder.
  37                 next->end = &delta_coder_end;
  38                 next->coder->next = LZMA_NEXT_CODER_INIT;
  39         }
  40
  41         // Validate the options.
  42         if (lzma_delta_coder_memusage(filters[0].options) == UINT64_MAX)
  43                 return LZMA_OPTIONS_ERROR;
  44
  45         // Set the delta distance.
  46         const lzma_options_delta *opt = filters[0].options;
  47         next->coder->distance = opt->dist;
  48
  49         // Initialize the rest of the variables.
  50         next->coder->pos = 0;
  51         memzero(next->coder->history, LZMA_DELTA_DIST_MAX);
  52
  53         // Initialize the next decoder in the chain, if any.
  54         return lzma_next_filter_init(&next->coder->next,
  55                         allocator, filters + 1);
  56 }
  57
  58
  59 extern uint64_t
  60 lzma_delta_coder_memusage(const void *options)
  61 {
  62         const lzma_options_delta *opt = options;
  63
  64         if (opt == NULL || opt->type != LZMA_DELTA_TYPE_BYTE
  65                         || opt->dist < LZMA_DELTA_DIST_MIN
  66                         || opt->dist > LZMA_DELTA_DIST_MAX)
  67                 return UINT64_MAX;
  68
  69         return sizeof(lzma_coder);
  70 }