bit-shift

Consider the following code (where byteIndex is an int): int bitNumber = b-(8*byteIndex); bitMask = 0x8>>(byte)bitNumber; This generates the error error: possible loss of precision when compiled (required byte, found int). The code int bitNumber = b-(8*byteIndex); bitMask = 0x8>>2; compiles fine. What is the problem here and how do I fix the first example to allow bit shifting by the int value? EDIT: Following the comments, here is a more-complete example: 48) int byteIndex; 49) byte bitMask; 50) int bitNumber; // assign value to byteIndex 67) bitNumber = b-(8*byteIndex); 68) bitMask = 0x8>

I'm a bit naive when it comes to bitwise logic and I have what is probably a simple question... basically if I have this (is ActionScript but can apply in many languages): var color:uint = myObject.color; var red:uint = color >>> 16; var green:uint = color >>> 8 & 0xFF; var blue:uint = color & 0xFF; I was wondering what exactly the `& 0xFF' is doing to green and blue. I understand what an AND operation does, but why is it needed (or a good idea) here? The source for this code was here: http://alexgblog.com/?p=680 Appreciate the tips. Alex In RGB you have 8 bits for Red, 8 bits for Green and 8

SHLD/SHRD instructions are assembly instructions to implement multiprecisions shifts. Consider the following problem: uint64_t array[4] = {/*something*/}; left_shift(array, 172); right_shift(array, 172); What is the most efficient way to implement left_shift and right_shift , two functions that operates a shift on an array of four 64-bit unsigned integer as if it was a big 256 bits unsigned integer? Is the most efficient way of doing that is by using SHLD/SHRD instructions, or is there better (like SIMD versions) instructions on modern architecture? In this answer I'm only going to talk about

I'm working through the exercises in the K&R book. Currently I'm stuck at exercise 2-8, which is says the following: Write a function rightrot(x, n) that returns the value of the integer x rotated to the right by n bit positions. The trouble I have is that I cannot seem to picture what the result SHOULD look like. How or what do I rotate? Do I take the leftmost bit and put it to the rightmost position of x , after x is shifted to the left and repeat this for n bits? Or do I take a chunk ( n bits) and put it n bits to the right while leaving the rest of the rightmost bits unchanged? Any helpful

I totally understand how to shift bits. I've worked through numerous examples on paper and in code and don't need any help there. I'm trying to come up with some real world examples of how bit shifting is used. Here are some examples I've been able to come up with: Perhaps the most important example I could conceptualize had to do with endianness. In big endian systems, least significant bits are stored from the left, and in little endian systems, least significant bits are stored from the right. I imagine that for files and networking transmissions between systems which use opposite endian