src/liblzma/simple/armthumb.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       armthumb.c
   4 /// \brief      Filter for ARM-Thumb binaries
   5 ///
   6 //  Authors:    Igor Pavlov
   7 //              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 ///////////////////////////////////////////////////////////////////////////////
  13
  14 #include "simple_private.h"
  15
  16
  17 static size_t
  18 armthumb_code(void *simple lzma_attribute((__unused__)),
  19                 uint32_t now_pos, bool is_encoder,
  20                 uint8_t *buffer, size_t size)
  21 {
  22         size_t i;
  23         for (i = 0; i + 4 <= size; i += 2) {
  24                 if ((buffer[i + 1] & 0xF8) == 0xF0
  25                                 && (buffer[i + 3] & 0xF8) == 0xF8) {
  26                         uint32_t src = ((buffer[i + 1] & 0x7) << 19)
  27                                         | (buffer[i + 0] << 11)
  28                                         | ((buffer[i + 3] & 0x7) << 8)
  29                                         | (buffer[i + 2]);
  30
  31                         src <<= 1;
  32
  33                         uint32_t dest;
  34                         if (is_encoder)
  35                                 dest = now_pos + (uint32_t)(i) + 4 + src;
  36                         else
  37                                 dest = src - (now_pos + (uint32_t)(i) + 4);
  38
  39                         dest >>= 1;
  40                         buffer[i + 1] = 0xF0 | ((dest >> 19) & 0x7);
  41                         buffer[i + 0] = (dest >> 11);
  42                         buffer[i + 3] = 0xF8 | ((dest >> 8) & 0x7);
  43                         buffer[i + 2] = (dest);
  44                         i += 2;
  45                 }
  46         }
  47
  48         return i;
  49 }
  50
  51
  52 static lzma_ret
  53 armthumb_coder_init(lzma_next_coder *next, const lzma_allocator *allocator,
  54                 const lzma_filter_info *filters, bool is_encoder)
  55 {
  56         return lzma_simple_coder_init(next, allocator, filters,
  57                         &armthumb_code, 0, 4, 2, is_encoder);
  58 }
  59
  60
  61 extern lzma_ret
  62 lzma_simple_armthumb_encoder_init(lzma_next_coder *next,
  63                 const lzma_allocator *allocator,
  64                 const lzma_filter_info *filters)
  65 {
  66         return armthumb_coder_init(next, allocator, filters, true);
  67 }
  68
  69
  70 extern lzma_ret
  71 lzma_simple_armthumb_decoder_init(lzma_next_coder *next,
  72                 const lzma_allocator *allocator,
  73                 const lzma_filter_info *filters)
  74 {
  75         return armthumb_coder_init(next, allocator, filters, false);
  76 }