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Is there a built in function in python which will convert a binary string, for example '111111111111', to the two's complement integer -1?
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To get 2's complement of binary number is 1's complement of given number plus 1 to the least significant bit (LSB). For example 2's complement of binary number 10010 is (01101) + 1 = 01110.
For example, 2's complement of “01000” is “11000” (Note that we first find one's complement of 01000 as 10111). If there are all 1's (in one's complement), we add an extra 1 in the string. For example, 2's complement of “000” is “1000” (1's complement of “000” is “111”).
Two's complement subtracts off (1<<bits) if the highest bit is 1. Taking 8 bits for example, this gives a range of 127 to -128.
A function for two's complement of an int...
def twos_comp(val, bits): """compute the 2's complement of int value val""" if (val & (1 << (bits - 1))) != 0: # if sign bit is set e.g., 8bit: 128-255 val = val - (1 << bits) # compute negative value return val # return positive value as is Going from a binary string is particularly easy...
binary_string = '1111' # or whatever... no '0b' prefix out = twos_comp(int(binary_string,2), len(binary_string)) A bit more useful to me is going from hex values (32 bits in this example)...
hex_string = '0xFFFFFFFF' # or whatever... '0x' prefix doesn't matter out = twos_comp(int(hex_string,16), 32) If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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