Unless you’re working in a shop and a codebase where bit-shifting is common then, IMHO, you’re risking obfuscation. Yes, the expressions may be logically equivalent but: A n00b might get confused by the alternate syntax An old guy who hasn’t had to do any bit-shifting since college, like myself, might get confused If you bit … Read more
This little test is actually more subtle than it looks as the behavior is implementation defined: unsigned char x = 255; no ambiguity here, x is an unsigned char with value 255, type unsigned char is guaranteed to have enough range to store 255. printf(“%x\n”, x); This produces ff on standard output but it would … Read more
Airflow represents workflows as directed acyclic graphs. A workflow is any number of tasks that have to be executed, either in parallel or sequentially. The “>>” is Airflow syntax for setting a task downstream of another. Diving into the incubator-airflow project repo, models.py in the airflow directory defines the behavior of much of the high … Read more
Let’s take it one step at a time. Integer.parseInt(“11010100”, 2) – this is the int value 212. This is, by the way, needless; you can just write: 0b11010100. 0b11010100 << 1 is the same as 0b110101000, and is 424. You then cast it to a byte: (byte)(0b11010100 << 1). The bits beyond the first 8 … Read more
It looks like your implementation is probably doing an arithmetic bit shift with two’s complement numbers. In this system, it shifts all of the bits to the right and then fills in the upper bits with a copy of whatever the last bit was. So for your example, treating int as 32-bits here: nPosVal = … Read more
First remember that machine words are of fixed size. Say 4, and that your input is: +—+—+—+—+ | a | b | c | d | +—+—+—+—+ Then pushing everything one position to the left gives: +—+—+—+—+ | b | c | d | X | +—+—+—+—+ Question what to put as X? with a … Read more
Some instruction sets are limited to one bit shift per instruction. And some instruction sets allow you to specify any number of bits to shift in one instruction, which usually takes one clock cycle on modern processors (modern being an intentionally vague word). See dan04’s answer about a barrel shifter, a circuit that shifts more … Read more
When you write 1 << n You shift the bit combination 000000001 for n times left and thus put n into the exponent of 2: 2^n So 1 << 10 Really is 1024 For a list of say 5 items your for will cycle 32 times.
Maybe writing the values in hexadecimal (or binary) helps 🙂 enum { kCGDisplayBeginConfigurationFlag = (1 << 0), /* 0b0000000000000001 */ kCGDisplayMovedFlag = (1 << 1), /* 0b0000000000000010 */ kCGDisplaySetMainFlag = (1 << 2), /* 0b0000000000000100 */ kCGDisplaySetModeFlag = (1 << 3), /* 0b0000000000001000 */ kCGDisplayAddFlag = (1 << 4), /* 0b0000000000010000 */ kCGDisplayRemoveFlag = (1 … Read more
Well, the official Java tutorial Bitwise and Bit Shift Operators covers the actual operations that are available in Java, and how to invoke them. If you’re wondering “what can I do with bit-shifting”, then that’s not Java specific, and since it’s a low-level technique I’m not aware of any list of “cool things you can” … Read more