forked from OSchip/llvm-project
126 lines
3.5 KiB
Python
126 lines
3.5 KiB
Python
"Collection of tools for displaying bit representation of numbers."""
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import StringIO
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def binary(n, width=None):
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"""
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Return a list of (0|1)'s for the binary representation of n where n >= 0.
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If you specify a width, it must be > 0, otherwise it is ignored. The list
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could be padded with 0 bits if width is specified.
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"""
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l = []
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if width and width <= 0:
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width = None
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while n > 0:
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l.append(1 if n & 1 else 0)
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n = n >> 1
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if width:
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for i in range(width - len(l)):
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l.append(0)
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l.reverse()
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return l
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def twos_complement(n, width):
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"""
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Return a list of (0|1)'s for the binary representation of a width-bit two's
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complement numeral system of an integer n which may be negative.
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"""
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val = 2**(width - 1)
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if n >= 0:
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if n > (val - 1):
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return None
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# It is safe to represent n with width-bits.
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return binary(n, width)
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if n < 0:
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if abs(n) > val:
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return None
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# It is safe to represent n (a negative int) with width-bits.
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return binary(val * 2 - abs(n))
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# print binary(0xABCD)
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# [1, 0, 1, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 1]
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# print binary(0x1F, 8)
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# [0, 0, 0, 1, 1, 1, 1, 1]
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# print twos_complement(-5, 4)
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# [1, 0, 1, 1]
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# print twos_complement(7, 4)
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# [0, 1, 1, 1]
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# print binary(7)
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# [1, 1, 1]
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# print twos_complement(-5, 64)
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# [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]
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def positions(width):
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"""Helper function returning a list describing the bit positions.
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Bit positions greater than 99 are truncated to 2 digits, for example,
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100 -> 00 and 127 -> 27."""
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return ['{0:2}'.format(i)[-2:] for i in reversed(range(width))]
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def utob(debugger, command_line, result, dict):
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"""Convert the unsigned integer to print its binary representation.
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args[0] (mandatory) is the unsigned integer to be converted
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args[1] (optional) is the bit width of the binary representation
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args[2] (optional) if specified, turns on verbose printing"""
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args = command_line.split()
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try:
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n = int(args[0], 0)
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width = None
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if len(args) > 1:
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width = int(args[1], 0)
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if width < 0:
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width = 0
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except:
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print utob.__doc__
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return
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if len(args) > 2:
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verbose = True
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else:
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verbose = False
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bits = binary(n, width)
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if not bits:
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print "insufficient width value: %d" % width
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return
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if verbose and width > 0:
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pos = positions(width)
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print ' ' + ' '.join(pos)
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print ' %s' % str(bits)
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def itob(debugger, command_line, result, dict):
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"""Convert the integer to print its two's complement representation.
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args[0] (mandatory) is the integer to be converted
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args[1] (mandatory) is the bit width of the two's complement representation
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args[2] (optional) if specified, turns on verbose printing"""
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args = command_line.split()
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try:
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n = int(args[0], 0)
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width = int(args[1], 0)
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if width < 0:
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width = 0
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except:
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print itob.__doc__
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return
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if len(args) > 2:
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verbose = True
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else:
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verbose = False
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bits = twos_complement(n, width)
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if not bits:
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print "insufficient width value: %d" % width
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return
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if verbose and width > 0:
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pos = positions(width)
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print ' ' + ' '.join(pos)
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print ' %s' % str(bits)
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