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  1. #
  2. # Copyright (c) 2008 Martin Decky
  3. # All rights reserved.
  4. #
  5. # Redistribution and use in source and binary forms, with or without
  6. # modification, are permitted provided that the following conditions
  7. # are met:
  8. #
  9. # - Redistributions of source code must retain the above copyright
  10. #   notice, this list of conditions and the following disclaimer.
  11. # - Redistributions in binary form must reproduce the above copyright
  12. #   notice, this list of conditions and the following disclaimer in the
  13. #   documentation and/or other materials provided with the distribution.
  14. # - The name of the author may not be used to endorse or promote products
  15. #   derived from this software without specific prior written permission.
  16. #
  17. # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18. # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19. # OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20. # IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21. # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22. # NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23. # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24. # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25. # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26. # THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27. #
  28. """
  29. Convert descriptive structure definitions to structure object
  30. """
  31.  
  32. import struct
  33.  
  34. class Struct:
  35.     def size(self):
  36.         return struct.calcsize(self._format_)
  37.    
  38.     def pack(self):
  39.         args = []
  40.         for variable in self._args_:
  41.             if (isinstance(self.__dict__[variable], list)):
  42.                 for item in self.__dict__[variable]:
  43.                     args.append(item)
  44.             else:
  45.                 args.append(self.__dict__[variable])
  46.        
  47.         return struct.pack(self._format_, *args)
  48.  
  49. def create(definition):
  50.     "Create structure object"
  51.    
  52.     tokens = definition.split(None)
  53.    
  54.     # Initial byte order tag
  55.     format = {
  56.         "little:":  lambda: "<",
  57.         "big:":     lambda: ">",
  58.         "network:": lambda: "!"
  59.     }[tokens[0]]()
  60.     inst = Struct()
  61.     args = []
  62.    
  63.     # Member tags
  64.     comment = False
  65.     variable = None
  66.     for token in tokens[1:]:
  67.         if (comment):
  68.             if (token == "*/"):
  69.                 comment = False
  70.             continue
  71.        
  72.         if (token == "/*"):
  73.             comment = True
  74.             continue
  75.        
  76.         if (variable != None):
  77.             subtokens = token.split("[")
  78.            
  79.             if (len(subtokens) > 1):
  80.                 format += "%d" % int(subtokens[1].split("]")[0])
  81.            
  82.             format += variable
  83.            
  84.             inst.__dict__[subtokens[0]] = None
  85.             args.append(subtokens[0])
  86.            
  87.             variable = None
  88.             continue
  89.        
  90.         if (token[0:8] == "padding["):
  91.             size = token[8:].split("]")[0]
  92.             format += "%dx" % int(size)
  93.             continue
  94.        
  95.         variable = {
  96.             "char":     lambda: "s",
  97.             "uint8_t":  lambda: "B",
  98.             "uint16_t": lambda: "H",
  99.             "uint32_t": lambda: "L",
  100.             "uint64_t": lambda: "Q",
  101.            
  102.             "int8_t":   lambda: "b",
  103.             "int16_t":  lambda: "h",
  104.             "int32_t":  lambda: "l",
  105.             "int64_t":  lambda: "q"
  106.         }[token]()
  107.    
  108.     inst.__dict__['_format_'] = format
  109.     inst.__dict__['_args_'] = args
  110.     return inst
  111.