I'm in a computer systems course and have been struggling, in part, with Two's Complement. I want to understand it but everything I read hasn't brought the picture together for me. I've read the wikipeida article and various other articles including my text book. Hence, I wanted to start this community wiki post to define what Two's Com...
I'm just curious if there's a reason why in order to represent -1 in binary, two's complement is used: flipping the bits and adding 1? -1 is represented by 11111111 (two's complement) rather than (to me more intuitive) 10000001 which is binary 1 with first bit as negative flag. Disclaimer: I don't rely on binary arithmetic for my job! ...
Is there a built in function in python which will convert a binary string, for example '111111111111', to the two's complement integer -1? ...
I'm watching some great lectures from David Malan (here) that is going over binary. He talked about signed/unsigned, 1's compliment, and 2's complement representations. There was an addition done of 4 + (-3) which lined up like this: 0100 1101 (flip 0011 to 1100, then add "1" to the end) ---- 0001 But he waved his magical hands and th...
Why byte b = (byte) 0xFF is equal to integer -1? Ex: int value = byte b = (byte) 0xFF; System.out.println(value); it will print -1? ...
I want to know the logic behind this statement, the proof. The C expression -x, ~x+1, and ~(x-1) all yield the same results for any x. I can show this is true for specific examples. I think the way to prove this has something to do with the properties of two's complement. Any ideas? ...
Why bitwise operation (~0); prints -1 ? In binary , not 0 should be 1 . why ? ...
I've decided to do it this way flip numbers 0=1, 1=0 add 1 to LSB if carry, loop until array[i]==0 But I'm stuck on the last point; how can I say that in a conditional loop? ...
I have a control that has a byte array in it. Every now and then there are two bytes that tell me some info about number of future items in the array. So as an example I could have: ... ... Item [4] = 7 Item [5] = 0 ... ... The value of this is clearly 7. But what about this? ... ... Item [4] = 0 Item [5] = 7 ... ... Any idea on...
We have 2's complement for integers that allows us to perform operations without worrying about the sign. That is a big help at the implementation level. Similarly we have so many floating point operations and yet we rely on sign and magnitude. What is the reason? Why can't a 2's complement like system work for floats? ...
I want to multiply two numbers, and detect if there was an overflow. What is the simplest way to do that? ...
Say I had a 6 digit hexadecimal signed in two's complement. What would be its range? -(16 ^ 5) < x < (16 ^ 5) Correct? ...
I need a function to convert a 32bit or 24bit signed (in two's complement) hexadecimal string into a long int. Needs to work on both 32bit and 64bit machines (regardless of the size of long int) and work regardless of whether the machine is a two's complement machine or not. SOLUTION: long int hex2li (char hexStr[], int signedHex) { ...
Hi every one. I am new programmer in Obj-C and cocoa. Im a trying to write a framework which will be used to read a binary files (Flexible Image Transport System or FITS binary files, usually used by astronomers). The binary data, that I am interested to extract, can have various formats and I get its properties by reading the header of...
I'm working with a proprietary protocol that transmits integers as 16 bit two's complement in two parts. The LSB is transmitted first followed by the MSB. Is the following code to restore the original value correct? unsigned char message[BLK_SIZE]; // read LSB to message[0] and MSB to message[1] short my_int = (message[1] << 8) | messag...
I have a negative integer (4 bytes) of which I would like to have the hexadecimal form of its two's complement representation. >>> i = int("-312367") >>> "{0}".format(i) '-312367' >>> "{0:x}".format(i) '-4c42f' But I would like to see "FF..." ...
I need to convert bytes in two's complement format to positive integer bytes. The range -128 to 127 mapped to 0 to 255. Examples: -128 (10000000) -> 0 , 127 (01111111) -> 255, etc. EDIT To clear up the confusion, the input byte is (of course) an unsigned integer in the range 0 to 255. BUT it represents a signed integer in the range -1...
The ISO C standard allows three encoding methods for signed integers: two's complement, one's complement and sign/magnitude. What's an efficient or good way to detect the encoding at runtime (or some other time if there's a better solution)? I want to know this so I can optimise a bignum library for the different possibilities. I plan ...
Using six-bit one's and two's complement representation I am trying to solve the following problem: 12 - 7 Now, i take 12 in binary and 7 in binary first. 12 = 001100 - 6 bit 7 = 000111 - 6 bit Then, would I then flip the bit for two's complement and add one? 12 = 110011 ones complement + 1 ------- 001101 7 ...
I am trying to learn Binary Multiplication, 2's complement negative numbers. -10 x 3 I know there is a simple way of doing this. Like sign extension and initial partial product. -10 0110 twos complement x 3 x 0011 ---- ------ 000000 (initial partial product) with sign extension at the MSB 10110...