lldb/examples/customization/bin-utils/binutils.py

   1 "Collection of tools for displaying bit representation of numbers."""
   2
   3 def binary(n, width=None):
   4     """
   5     Return a list of (0|1)'s for the binary representation of n where n >= 0.
   6     If you specify a width, it must be > 0, otherwise it is ignored.  The list
   7     could be padded with 0 bits if width is specified.
   8     """
   9     l = []
  10     if width and width <= 0:
  11         width = None
  12     while n > 0:
  13         l.append(1 if n & 1 else 0)
  14         n = n >> 1
  15
  16     if width:
  17         for i in range(width - len(l)):
  18             l.append(0)
  19
  20     l.reverse()
  21     return l
  22
  23
  24 def twos_complement(n, width):
  25     """
  26     Return a list of (0|1)'s for the binary representation of a width-bit two's
  27     complement numeral system of an integer n which may be negative.
  28     """
  29     val = 2**(width - 1)
  30     if n >= 0:
  31         if n > (val - 1):
  32             return None
  33         # It is safe to represent n with width-bits.
  34         return binary(n, width)
  35
  36     if n < 0:
  37         if abs(n) > val:
  38             return None
  39         # It is safe to represent n (a negative int) with width-bits.
  40         return binary(val * 2 - abs(n))
  41
  42 # print binary(0xABCD)
  43 # [1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1]
  44 # print binary(0x1F, 8)
  45 # [0, 0, 0, 1, 1, 1, 1, 1]
  46 # print twos_complement(-5, 4)
  47 # [1, 0, 1, 1]
  48 # print twos_complement(7, 4)
  49 # [0, 1, 1, 1]
  50 # print binary(7)
  51 # [1, 1, 1]
  52 # print twos_complement(-5, 64)
  53 # [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1]
  54
  55
  56 def positions(width):
  57     """Helper function returning a list describing the bit positions.
  58     Bit positions greater than 99 are truncated to 2 digits, for example,
  59     100 -> 00 and 127 -> 27."""
  60     return ['{0:2}'.format(i)[-2:] for i in reversed(range(width))]
  61
  62
  63 def utob(debugger, command_line, result, dict):
  64     """Convert the unsigned integer to print its binary representation.
  65     args[0] (mandatory) is the unsigned integer to be converted
  66     args[1] (optional) is the bit width of the binary representation
  67     args[2] (optional) if specified, turns on verbose printing"""
  68     args = command_line.split()
  69     try:
  70         n = int(args[0], 0)
  71         width = None
  72         if len(args) > 1:
  73             width = int(args[1], 0)
  74             if width < 0:
  75                 width = 0
  76     except:
  77         print(utob.__doc__)
  78         return
  79
  80     if len(args) > 2:
  81         verbose = True
  82     else:
  83         verbose = False
  84
  85     bits = binary(n, width)
  86     if not bits:
  87         print("insufficient width value: %d" % width)
  88         return
  89     if verbose and width > 0:
  90         pos = positions(width)
  91         print(' ' + ' '.join(pos))
  92     print(' %s' % str(bits))
  93
  94
  95 def itob(debugger, command_line, result, dict):
  96     """Convert the integer to print its two's complement representation.
  97     args[0] (mandatory) is the integer to be converted
  98     args[1] (mandatory) is the bit width of the two's complement representation
  99     args[2] (optional) if specified, turns on verbose printing"""
 100     args = command_line.split()
 101     try:
 102         n = int(args[0], 0)
 103         width = int(args[1], 0)
 104         if width < 0:
 105             width = 0
 106     except:
 107         print(itob.__doc__)
 108         return
 109
 110     if len(args) > 2:
 111         verbose = True
 112     else:
 113         verbose = False
 114
 115     bits = twos_complement(n, width)
 116     if not bits:
 117         print("insufficient width value: %d" % width)
 118         return
 119     if verbose and width > 0:
 120         pos = positions(width)
 121         print(' ' + ' '.join(pos))
 122     print(' %s' % str(bits))