bit-shift

I'm in the unique situation where searching for "most significant bit" yields too many results and I can't find an answer that fits my needs! The question itself is pretty simple: "How do I find the most significant set bit in an unsigned long?" When I do my calculations the rightmost bit position is position '0'. I know that it involves masking the lowest bit, checking and then shifting left to once while incrementing my count, and then repeating with the 2nd lowest, etc. I've done this before but for whatever reason I can't do it now. Edit: By "most significant" I mean leftmost set bit,

After reading the great answer for Absolute Beginner's Guide to Bit Shifting? I tested the claim (sic): 3,758,096,384 << 1 from Chrome console: 3,758,096,384 << 1 > 768 3,758,096,384 << 2 > 1536 3758096384 << 1 > -1073741824 That's the comma operator at work. It's actually 384 << 1 . (The comma operator evaluates its left hand side, then evaluates its right hand side, and returns the right hand side.) It returns 768 because you're incorrectly using the comma operator. 3,758,096,384 << 1 will actually be 384 << 1 because the comma operator will return the last operand. 来源： https://stackoverflow

In C++ I have code like this. static UInt32 rol(UInt32 value, UInt32 bits) { bits &= 31; return ((value << bits) | (value >> (32 - bits))); } static UInt32 ror(UInt32 value, UInt32 bits) { bits &= 31; return ((value >> bits) | (value << (32 - bits))); } how would it look in C#? I think the same exact way.. only problem Error 2 Operator '>>' cannot be applied to operands of type 'uint' and 'uint' Error 3 Operator '>>' cannot be applied to operands of type 'uint' and 'uint' Error 1 Operator '<<' cannot be applied to operands of type 'uint' and 'uint' Error 4 Operator '<<' cannot be applied to

Given a certain integer x , I wish to compute the next higher integer y which has a certain hamming weight w . Mind that the hamming weight of x does not have to be w as well. So, for example x = 10 (1010) and w = 4 the result should be y = 15 (1111). Obviously, I could achieve this by just incrementing x but that would be a very slow solution for high numbers. Can I achieve this by the means of bit shifts somehow? There are three cases: the Hamming weight (a.k.a. bitwise population count) is reduced, unchanged, or increased. Increased Hamming weight Set enough successive low-order 0-bits to

This is false: (0xffffffff << 31 << 1) === (0xffffffff << 32) It seems like it should be true. Adding >>> 0 anywhere does not change this. Why is this and how can I correctly write code that handles << 32 ? The shift operators always effectively has a right operand in the range 0-31. From the Mozilla docs : Shift operators convert their operands to 32-bit integers in big-endian order and return a result of the same type as the left operand. The right operand should be less than 32, but if not only the low five bits will be used . Or from the ECMAscript 5 standard : The production

I'm confused by something I read in the Shift Operators section of an article on undefined C++ behavior . On the ARM architecture, the shift operators always behave as if they take place in a 256-bit pattern space, regardless of the operand size--that is, the pattern repeats, or "wraps around", only every 256 positions. Another way of thinking of this is that the pattern is shifted the specified number of positions modulo 256. Then, of course, the result contains just the least-significant bits of the pattern space. The tables are especially strange: Given a 32-bit integer with a value of 1: +

This code is for a cache simulator project - I am trying to extract certain bits from a memory address. When I attempt to use int variables to do the bit shifting, I end up with an incorrect result, but when I use the numbers directly, my result is correct. I've been looking all over for an answer to this, but I can't find one. What is my issue here? #include <stdio.h> void main(){ unsigned long long int mem_addr = 0x7fff5a8487c0; int byte_offset_bits = 2; int block_offset_bits = 5; int index_bits = 8; int tag_bits = 33; unsigned long long int tag1 = (mem_addr&(((1<<33)-1)<<(2+5+8)))>>(2+5+8);