I am having some fun with bit operations in C and i don’t get one thing. If i have char b = 0x6c, and then i have short y = 0x0000, and I do y=b; y = y >> 12;, why does it fill my y with ‘f’? #include <stdio.h> #include <stdlib.h> int main() {… Read More Automaticly filling bits in c with f while doing ">>" operation
This program displays certain messages when some of the elements are ‘y’ or if all of the elements are ‘n’. My question is about this line: someElements |= array[i] == ‘y’. I understand that it can be written in this way: someElements = someElements | array[i] == ‘y’. I’m just asking for an explanation why… Read More Displaying a message when a certain array element is present in C
I’d like to get the highest number with n bits in C++. I’ve written this piece of code but maybe there is a more efficient way. int A = 22; // 10110 int max = pow(2, (int) log2(A) + 1) – 1; // returns 31 (11111) This code raises 2 to the power of the… Read More Get highest number with n bits
How is the number of value bits in the result determined in the following operations: 5 = -3 & 5 # (1)11 & (0)101 -> (0)101 -3 = -3 | 5 # (1)11 & (0)101 -> (1)11 -8 = -3 ^ 5 # (1)11 ^ (0)101 -> (1)1000 ? So it seems that bitwise AND… Read More How is the bit length of a result of a bitwise operation for negative numbers calculated?
#include <stdio.h> #include <stdlib.h> void get_nbits(int num, int n); void replace_nbits(int num, int n, int val); void get_nbits_from_pos(int num, int n, int pos); void replace_nbits_from_pos(int num, int n, int pos, int val); void toggle_bits_from_pos(int num, int n, int pos); void print_bits(unsigned int num, int n); int main() { printf("\tThis program is to show the below… Read More *** stack smashing detected ***: terminated
I want to run a function multiple times and then do something if anything failed. So I set a flag before looping the calls, the called function comes back with a success/failure boolean but, if I use an in-line logical AND, the function is no longer called as though an IF statement exists. Can someone… Read More Golang Logical AND of result of function
This works as expected: > 0b1111 15 > 0b1111 & 0b1111 15 But this doesn’t: > 0b11111111111111111111111111111111 4294967295 > 0b11111111111111111111111111111111 & 0b11111111111111111111111111111111 -1 What’s going on here? And how can I safely perform bitwise operations on large (up to 2^32) numbers in Javascript? Update: This is below Number.MAX_SAFE_INTEGER so I don’t believe there should be… Read More Bitwise operations on large numbers
This is the code I have so far // given the 32 bits of a float return it with its sign flipped uint32_t sign_flip(uint32_t f) { int mask = 1; f = ~f; // 1’s Complement while (mask > 0 && (mask & f)) { f ^= mask; mask <<= 1; } f ^= mask;… Read More How to flip the sign of a float using bitwise operators in C
This is the code I have so far? But its not working.. uint64_t bit_swap(uint64_t value) { return ((value & 0xAAAAAAAA) >> 1) | ((value & 0x55555555) << 1); } bit_swap(0x1111111111111111) should return 0x2222222222222222 but is returning 0x0000000022222222 instead >Solution : value & 0xAAAAAAAA That is equivalent to : value & 0x00000000AAAAAAAA And since we know… Read More How to swap pairs of bits of unsigned int in C
I have the following bitwise operation that generates a hash: (z shl 28) or (y shl 14) or x // (z << 28 | y << 14 | x) in java I want to be able to deduce x, y and z from the hash calculated above. I can get Z and X every time,… Read More Unpacking three values packed into a Long