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