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 = (((uint32_t)(buffer[i + 1]) & 7) << 19)
      27  				| ((uint32_t)(buffer[i + 0]) << 11)
      28  				| (((uint32_t)(buffer[i + 3]) & 7) << 8)
      29  				| (uint32_t)(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  #ifdef HAVE_ENCODER_ARMTHUMB
      62  extern lzma_ret
      63  lzma_simple_armthumb_encoder_init(lzma_next_coder *next,
      64  		const lzma_allocator *allocator,
      65  		const lzma_filter_info *filters)
      66  {
      67  	return armthumb_coder_init(next, allocator, filters, true);
      68  }
      69  #endif
      70  
      71  
      72  #ifdef HAVE_DECODER_ARMTHUMB
      73  extern lzma_ret
      74  lzma_simple_armthumb_decoder_init(lzma_next_coder *next,
      75  		const lzma_allocator *allocator,
      76  		const lzma_filter_info *filters)
      77  {
      78  	return armthumb_coder_init(next, allocator, filters, false);
      79  }
      80  #endif