Swap bits in c

Swap bits in c. int swap_bit(int n, int pos1, pos2) {. 3) Right shift all even bits. I want 0b11101011 to become 0b11101110. Compute XOR from 1 to n (direct method): The problem can be solved based on the following observations: Say x = n%4. Talking about C/C++, especially in this specific context when C++ takes a totally different approach to the same problem, is incredibly wrong. E. Perform, x = a ^ b. How to swap n bits from 2 numbers? 0. Back to Explore Page. 10 11 01 10. Afaik bits. How can I swap 2 integers in C using bitwise operators and bit manipulation? 1. Multiplication is really a convolution operation, and you can use that to shuffle bits. I need to swap every two adjacent bits as a generic operation which will do so for every variable type given. The function below will swap bits 2 and 4. 51. Efficient Approach: Below is the idea to solve the problem. b=a^b. unsigned char mask2 = ( bytein & 0x04 ) << 2; unsigned char mask4 = ( bytein & 0x10 ) >> 2; Mar 2, 2021 · In this case, you have an 8-bit value, so the bits go from 0 on the right up to 7 on the left. In this problem, we are given, an unsigned integer N. firstNumber = firstNumber XOR secondNumber = 00000011. *but i could not able to understand how it is working. Oct 25, 2023 · This video is part of the Bit Manipulation section under the GFG SDE Sheet. Reversing is possible, too. The result of AND is 1 only if both bits are 1. This seemed a good 99% answer. The lowest bit will be either 0 or 1, depending on what's in x; said differently, the lowest bit will be the lowest bit in x, which is what we want. Apr 3, 2024 · Bitwise Algorithms. Suppose two integer values a and b. Output: 43. For clarity I have broken the steps otherwise an character array can be considered. 58 . Also, while the xor trick is clever, it's usually slower and more error-prone than using a temporary variable. The first assignment shifts the leftmost 4 bits to the right, and the rightmost 4 bits to the left, then combines them with OR, so the result is: 45670123. Pop bits from this stack into another array (or the same array if you want to save space), placing the first popped bit into MSB and going on to less significant bits from there. So lets say for example, key = 0110 1010, we only care about 1010 as its the least significant bit. The given program is compiled and executed using GCC compile on UBUNTU 18. Jul 22, 2022 · Given an integer n and two-bit positions p1 and p2 inside it, swap bits at the given positions. What it encapsulates is the bitset and a position in the bitset. Return the integer formed. Below is the implementation of above approach. If we swap the bits at position 0 and 3, it will be 110011 i. h> #include <stdlib. Edit: If you are not sure if your unsigned long 's size is 8 bytes, you could use uint64_t from inttypes. , to solve problems related to tasks such as setting, clearing, or toggling Feb 24, 2010 · got it. Feb 6, 2013 · The bytes is read from a RFIDTag via POS for . The idea is that the function takes 3 integers (int x, int y, int z) and the function will swap the y and z bytes of the int x. y = x|y; C program to read a byte and print bits between given positions; C program to swap two bits of a 32-bit integer number; C program to check a given number is the power of 2 using bitwise operator; C program to count the number of bits to be flipped to convert a number to another number Mar 3, 2014 · Think about how AND works: both bits must be set. unsigned long ulValue = ntohl(*piData); int iValue = static_cast<int>(ulValue); But in the case I receive an double, I don't know what to do. Well, we don’t but if we were implementing some sorting functions we’d need a good swap function. Third- just reverse the order of every four bytes (after your first 12 char offset). See this example to get clear view of XOR based concept. We're talking on native C here, btw. Somthing like this: unsigned int n = 12345; //Source. Mar 12, 2024 · Other Types of Pointers in C: There are also the following types of pointers available to use in C apart from those specified above: Far pointer: A far pointer is typically 32-bit that can access memory outside the current segment. Swap bits in a given number Given a number x and two positions (from the right side) in the binary representation of x, write a function that swaps n bits at given two positions and returns the result. In this C Program, we are reading the number using ‘n’ variable and also the bit positions using ‘p’ and ‘q’ variables respectively. Swapping different bits between 2 integers - C. It uses the GCC macro __BYTE_ORDER__ to check the system's byte order and define the macros based on that. Without lookup table (or to generate the thing in the first place) you can also: shift left and AND with left-bit mask (10101010) shift right and AND with right-bit mask (01010101) OR results together. Multiply that by 0b0101, and you get ABAB. Ex: Let first no whose bit is to be replaced is: 7 //0000 0111 Second no from whom bit is to be replaced 8 //0000 1000 Specified position: 3 (0-indxed) Converted number will be 15 C Code: Jun 23, 2012 · The longer answer is that you use the bit directly from the source: unsigned char bit = 1 << N; myChar &= ~bit; // Zero the bit without changing anything else myChar |= otherChar & bit; // copy the bit from the source to the destination. 4) Left shift all odd bits. Feb 3, 2020 · I have a C program below that will replace a specified bit of a number from another number. Rest of the thing remains same as above approach. I assumed the function would only be used for a single value (p points to the scalar object to be reversed, size is the number of bytes of the object) in which case it's a generalized routine to handle a 16-bit, 32-bit or 64-bit integral type. Examples : Input : 11. Recommended Practice. . – Basically, i want to reverse the bit order in a byte, so that the least significant bit becomes the most significant bit. Here is the program to swap bit in odd and even positions of 32-bit unsigned integer. In this program, we declared an unsigned char type variable to read 8 bits number (byte) and we are swapping two bits (1 and 2) of given number. This method of swapping is similar to the general purpose XOR Jan 5, 2024 · SHARE. Jun 11, 2009 · 2. Oct 11, 2001 · 2. STOP. Nov 19, 2017 at 21:49. a=a^b // now a becomes 15 or 1111 (10 XOR 5 = 15) b=a^b // now b becomes 10 or 1010 (15 XOR 5 = 10) Nov 15, 2023 · The function std::swap () is a built-in function in the C++ Standard Template Library (STL) which swaps the value of two variables. Third argument is an integer C. My approach was to use char *pointer and a temp char to swap the bytes. As we know all types of data including structures take a specific space of memory, for example 4 bytes, 8 bytes. Here, every even position bit is swapped with an adjacent bit on the right Dec 29, 2022 · A nibble is a four-bit aggregation or half an octet. You'll see that the swapped bits BA are the middle bits. What I need to get out of it is: 00 00000000 11101101 (int = 237) From the original bytes that would be the following bits in reverse order: -----10 11011100 00000000 Dec 12, 2012 · 1. C Program to Swap two Numbers using Bitwise Operators ; C Program to Count the Number of Bits to be Flipped to Convert X to Y ; C Program to Swap Two Bits for a 32-Bit Integer ; C Program to Perform Addition using Bitwise Operators ; C Program to Swap Two Elements of the List without Key Field ; C Program to Find Prime Numbers in a Given Range Feb 21, 2016 · I'm trying to swap the last two bits in a binary number with the previous 2 bits. Integer is a 4 byte wide i. We will use the same logic to solve this question. Well, the guy there told me it can be done within a single command. Visually: May 3, 2012 · To byte-swap a signed number while avoiding as much implementation-defined behavior as possible, you can make use of a wider signed intermediate, one that can represent the entire range of the unsigned type with the same width as the signed value you wanted to byte-swap. But right now we do. ) From Swapping bits at a given point between two bytes which explains how this algorithm works: unsigned bitdiff = num1 ^ num2; bitdiff &= 0xff; // only swap the low 8 bits num1 ^= bitdiff; num2 ^= bitdiff; With this replacing your loop, it can swap 4 and 7. Calling the intrinsics instead of rolling your own gives you the best performance and code density btw. Swap Bits - Problem Description Given an integer A. Means - they are signed. ptr+i will give the address of the i th byte of n whose value (ie, *(ptr+i)) is modified appropriately by the swap() function. Below is our given C++ program that will able to swap bits in a Nov 22, 2022 · To swap the bits subtract and add corresponding values. com Menu. If. – Jan 26, 2014 · C doesn't guarantee that signed integers will use any particular representation - without a clear definition of how numbers translate to/from bits, bit-fiddling is very bug-prone. x = 0, then the answer is n. That is four bits in each of two operands, so eight bits total, 256 combinations for a specific value of n. 1st it checks that the two bits are different or not, if diffrent then it toggled from 1 to 0 or from 0 to 1 and if same then it do nothing and simply return that number. Output : 1 3. After reversing the bits we get: It will become : firstNumber(9) : 00001001 secondNumber(10) : 00001010. This can be achieved by the code below. The XOR value depends on the value if x. org/problems/swap-bits5726/1 2) Get all odd bits of x by doing bitwise and of x with 0x55555555. // swap bits iIn = ((iIn>>4) & 0x0F) | ((iIn<<4) & 0xF0); // THIS is your solution here. – Ctx. Explanation with an Example Jan 8, 2024 · Bitwise Operators in C. Examples: Input: n = 28, p1 = 0, p2 = 3. Dec 28, 2016 · 12. @MikeSeymour true, but it's most likely that this is what the user needs. Jan 27, 2016 · We can use bitwise XOR ^ operator to swap to numbers. Output Format Return an integer. In C++, you don't implement a swap macro. Explanation: (11) 10 = (1011) 2. After swapping of bit 1 and 2. This function can easily swap bit positions pos1 and pos2 of a number n. Feb 25, 2013 · I am looking for a method to reverse the bytes in a character array. Taking your example of little-endian, 16-bit numbers: Please consume this content on nados. Oct 6, 2011 · Edit: As pointed out the byte swapped double "can" get loaded into a register so that getting it back out of that register can mean the value is no longer valid so store it in a long long, 64-bit to avoid this problem. Thank you Chris If you have a 64 bit machine with 64 bit integer support and you need to swap lotsa bits in bytes, this algorithm will swap 8 bytes at a time in around 20 instructions. Mar 28, 2022 · #gfgpractice #potdSolve this problem on your own: https://practice. Now I want to change the value at bit position 5 and 6 Jun 21, 2021 · Swap all adjacent bits in given number. Here is my code so far: #include <iostream>. However if by saying "same pointers" you mean different pointer variables which points to the same address - then NO, you can perfectly swap these two pointers. Masking is the act of applying a mask to a value. , to solve problems related to tasks such as setting, clearing, or toggling specific bits, checking if a number is even or odd, swapping values Jan 5, 2010 · First we have to look at the declaration of swap: Now, operator[]() on bitset has two overloads: Here reference is bitset::reference, a nested class in bitset that effectively acts as a proxy reference to the one of the underlying bits. Given a byte, swap the two nibbles in it. Step 2: swap two numbers by using BITWISE operator. C program to swap two bits of a number. for p’th bit – n & (1 << p)) >> p) for q’th bit – (n & (1 << q)) >> q) 3. nothing needs converted. Endianness does not involve bit swapping, but only byte swapping. Learn how to use XOR to swap two bits of a number in C using example. A = A XOR B. I have written a simple C header for converting the endianness of short integers and long integers. It is necessary to solve the questions while watching videos, nados. Jul 12, 2018 · I didn't downvote, but if you look at the example in the question, it's actually asking how to swap the byte order rather than how to swap two variables. pepcoding. We Apr 12, 2023 · The problem is to reverse the bits of n and print the number obtained after reversing the bits. Oct 13, 2010 · C - Swap a bit between two numbers. Do some Google searching for bit manipulation and it will make more sense. 0xCC is 11001100, and 0x33 is 00110011. Sep 11, 2012 · As an example of *swapping ranges of bits suppose we have have b = 00101111 (expressed in binary) and we want to swap the n = 3 consecutive bits starting at i = 1 (the second bit from the right) with the 3 consecutive bits starting at j = 5; the result would be r = 11100011 (binary). Nov 2, 2021 · Number after bits are swapped: 51. 04 OS successfully. Generic Swap We only want to have one swap function and not one for every single possible type. Given a number X and two positions (from right side) in binary representation of X, write a program that swaps N bits at given two positions and returns the result. Dec 12, 2018 · If the original number is 13 (00001101), then bits at odd and even position are swapped in following manner. bswap itself is ok as it's a reasonably known operation but what the heck is _bswap_a and _bswapf (it's also inconsistent _a vs f)? Please prefer more explanatory names like _bswap_array and _bswap_field. Jul 9, 2012 · Use htonl / ntohl provided by your OS. That's exactly what a XOR b does. Sometimes you don’t. a=a^b; We will perform these operations to swap two bits in a number. From big to little endianess, you have to reverse the whole bytes making up the data word, leave the bits alone. Below are some major key differences between std::swap and std::vector::swap, std::swapstd::vector::swapThe std::swap() is a built-in function in C++ STL whic May 23, 2013 · 5. x = x >> 8 shifts the leftmost (most significant) 8 bits of x to the right, replacing them with 0s. Example: Input number: 0x0A (Hexadecimal) Binary of input number: 0000 1010 After swapping of bit 1 and The left shift operator shifts the bits in the shift expression to the left by the specified number of positions in the additive expression. If we swap the two nibbles, we get 01000110 which is 70 in decimal. using namespace std; unsigned short int ByteSwap(unsigned short int *x); int main() Mar 5, 2021 · Step 1: declare two variables a and b. h. On of the ways to do this is to use bitwise operations if following this pseudo code: Y>>1. The parameters can be of any data type. 5) Combine new even and odd bits and return. Anyone writing some low level non-network order driver is likely to know how to do it anyway. How to swap pairs of bits of unsigned int in C. the byte order needs swapped, but ntohs/l () and htons/l () are both null macros on a big endian machine, so they won't swap the byte order. Dangling pointer: A pointer pointing to a memory location that has been deleted (or freed) is called a dangling Jun 13, 2014 · With the following method we can swap two variable A and B. The given positions are from the least significant bit (lsb). Instead, write a loop that prints the 31st bit (n&0x80000000) and shifts the number left. First, you need to make sure you know what size your integers are. There are two nibbles in a byte. Example: Input number: 0x0A (Hexadecimal) Binary of input number: 0000 1010. Mar 18, 2020 · (Instead of left shifting a single-bit mask in a loop. It means: assign the value 0x34 to c; store the bottom 4 bits of c in temp1; store the top 4 bits of c in temp2; shift the bits in temp1 4 places left; shift the bits in temp2 4 places right; OR temp2 and temp1 together to create an 8-bit value. (Acctually I need 18 bits) In binary the byte array is as follows: 00001110 11011100 00000000 00011011 10000000. Since we're ANDing with 1, all bits except the first must be 0, because they're 0 in 0x01. c1 = 0010 1011. This can be achieved using bitwise operations in C programming. Apr 3, 2024 · Bitwise algorithms in Data Structures and Algorithms (DSA) involve manipulating individual bits of binary representations of numbers to perform operations efficiently. x= byte & 1. Next step is to Apr 14, 2009 · Starting from MSB, push bits into a stack one by one. Jul 31, 2021 · The source code to swap two bits of a 32-bit integer number is given below. Second argument is an integer B. e. 0xF0 in binary is 11110000, and 0x0F is 00001111. Now x ^ b will evaluate to a. I also need to reverse the individual bits of the bytes being swapped before positioning them in the right place. h> int main ( int argc, char* argv[]) {. byte >>1. Aug 27, 2015 · In the case I receive an int I perform this code using ntohl : int * piData = reinterpret_cast<int*>((void*)pData); //manage endianness of incomming network data. a=a^b. Bitwise algorithms in Data Structures and Algorithms (DSA) involve manipulating individual bits of binary representations of numbers to perform operations efficiently. Oct 12, 2012 · If key has any 1's in its least significant bits, then the bits of c1 need to be swapped according to its corresponding mirror bit positions. 1. The restrictions are pretty much limited to bit wise operations (no loops, and no if statements or logical operators such as ==). The header creates the macros LITTLE_ENDIAN_SHORT(n), LITTLE_ENDIAN_LONG(n), BIG_ENDIAN_SHORT(n), BIG_ENDIAN_LONG(n) which convert the May 8, 2012 · A mask defines which bits you want to keep, and which bits you want to clear. geeksforgeeks. & 0xff and similar masks off the 8 bits that need to be shifted (or were shifted) to the opposite endian byte. and x ^ a will evaluate to b. The two nibbles are (0110) and (0100). Apr 17, 2024 · A nibble is a four-bit aggregation or half an octet. Now if we follow 3 steps x=x^y y=x^y & x=x^y; we will obtain the swapping of x and y bits. Say for example: I have a 64-bit register where bits 5 and 6 can take values 0, 1, 2, and 3. They are used to perform bitwise operations in C. Return Value: Jan 29, 2015 · I have this function called byte swap I am supposed to implement. It's that simple. Jul 28, 2017 · XOR with 1 flips a bit; XOR with 0 is a no-op. You can use this to precompute a lookup table, if necessary (so that swapping becomes a single operation): unsigned char swap24(unsigned char bytein) {. For example, if the given number is 23 (00010111), it should be converted to 43 (00101011). Swap byte 2 and byte 4 within an integer sequence. I find code like this confusing to read (the pointer alias is confusing to me): Apr 18, 2023 · This method is used to set the bit at a particular position (say i) of the given number N. For example, the position for lsb is 0. Problem Constraints 1 <= A < 230 1 <= B, C <= 30 Input Format First argument is an integer A. B = A XOR B. This is accomplished by doing: Below is an example of extracting a subset of the bits in the value: Applying the mask to the value means that we want to clear the first (higher) 4 bits, and keep the last (lower) 4 bits. The task is to swap all odd bits with even bits. This question does not concern or relate to C++. How to address it in C language if the segment is not sequential? For example, a is 011*001*10, input segment length:5, start position pa=5, the segment is from bit7~bit5 and bit1~bit0, which is 011 10; b is 10*011*001, position pb=6, the segment is from bit6 Sep 21, 2023 · The std::swap is a general function used to exchange the given values whereas the std::vector::swap is a specialized function that can swap all the contents of two different vector containers. Binary will be: 0000 1100. 2. In the above example, you can see that the firstNumber Feb 11, 2020 · Dec 13, 2011 at 4:23. Nov 12, 2016 · As an example of swapping ranges of bits suppose we have have b = 00101111 (expressed in binary) and we want to swap the n = 3 consecutive bits starting at i = 1 (the second bit from the right) with the 3 consecutive bits starting at j = 5; the result would be r = 11100011 (binary). Sorting typically doesn’t move pointers around, instead it moves the bytes pointed to by the pointer. The & (bitwise AND) in C takes two numbers as operands and does AND on every bit of two numbers. . Now you can access and manipulate the array one byte at a time. Obtain the odd bits and shift these to even positions. unsigned char *b2, *b4, tmpc; int n = 0xABCD; ///expected output Sep 26, 2012 · I would like to swap a segment of bits between 2 unsigned char_type variables:a and b. Example: We have a=10 and b=5, so. // C program to swap two bits of a // 32-bit integer number #include <stdio. Oct 30, 2013 · (Always faster on more than 3 characters or six bytes, a bit slower on less or equal to three characters or six bytes. In practice the representation will be twos complement for any not-completely-strange platform, but compilers are increasingly exploiting undefinedness for Feb 7, 2014 · How it works: bitmask = 0x00FF makes bitmask a value with 8 leading zero bits and then 8 trailing 1s. 32 bits is nice and standard, but check and make sure. A big endian compiled analyzer run on a little endian object file. For Even- To do this we can AND with bitmask 0xAAAAAAAAAA. After swapping, the bits are: Algorithm: Create a mask to obtain the 0xAAAAAAAA to extract bits. For example: 1001 1101 = 9D would become 1011 1001 = B9. firstNumber = firstNumber XOR secondNumber = 00000011 XOR 00001001 = 00001010. Second, cast your integer array as a char array. The number 0xAAAAAAAA which is a 32 bit number with even bits set (0xA is decimal 10, 1010 binary). Step 3: Print a and b values. The given problem aims to swap all adjacent bits in a given number. Mar 28, 2023 · If we closely look at the operations we see that first we swap the odd and even bits then we swap consecutive pairs then nibbles and then bytes and 2 bytes and so on, the code executes in reverse order. Simply mask this to only swap some of the bits, and we have a bit-swap in 3 XORs + 1 AND. If the value return is 1 then the bit at the ith position is set. 0000 in Binary What is the easiet way? For swap integer (short) I use htonl (htons). May 7, 2024 · Finding the most significant set bit (MSB) Check if a number has bits in an alternate pattern. shifted left is 01 10 11 00 masked with 10101010 gives us 00 10 10 00. Swap the Bth and Cth bit from right in binary representation of A. Perhaps you're getting the weird outputs because the bitshift don't work exactly as you may expect. That will only swap bytes if the native format is the reverse of network format. Oct 28, 2021 · I'll ignore the top bits for a second - there's a trick using multiplication. 58 is : 111010 . The idea is to update the value of the given number N to the Bitwise OR of the given number N and 2i that can be represented as (1 << i). In particular, assume the two lower bits are AB. 32 bits. Your variables are of type int. com for a richer experience. int num = 0 ; Apr 27, 2012 · Basically, there are four possible scenarios: A big endian compiled analyzer run on a big endian object file. Note that the actual binary representation of the number is being considered for reversing the bits, no leadings 0’s are being considered. subtract i_bit<<i and add it at i+1 index for that we need to add i_bit<< (i+1). So what we want is a value that has a 1 everywhere there's a bit-difference between the inputs, and a 0 everywhere else. Jun 27, 2011 · Your idea is ok. Jul 1, 2013 · I had this interview question -. I want to implement such a method in C++ that operate with all types (int, float, char, ) as well as structures. Then test values of n from 2 to 126. If we swap the bits at position 0 and 2, it will be 111010 i. This assumes you want to copy bit N from the source to bit N of the destination. Menu. For Odd – For selecting all the odd bits we can AND with bitmask 0×55555555, which is a Sep 9, 2017 · swap(ptr, 6, 7); The address of n is cast into a char pointer and stored in ptr. I thought of the needed masks and operations for every single byte: (var &amp; 0x55) (no need to include something). h declares the same function in a non gcc-centric way as well. To remove bit at ith bit to i+1. One of the question i've been asked was: how can one replace the 4 higher bits of a byte with its 4 lower bits. Net. ) ( Note that the accepted answer can read/write outside the bounds of the array. +1 for good clarification. Before you do that loop, do another loop that shifts the number left until the 31st bit is 1; unless you do that, you'll get leading zeros. Thats all there is to a byte swap. The answer to the question suggest to do Apr 4, 2022 · A good test suite would include all combinations of bits in the critical positions: The high bit, the lowest bit swapped, the highest bit not swapped, and the lowest bit. Here are the steps it's doing: Pull out bit 2 (which is 3rd from the right) using a mask; Pull out bit 4 (which is 5th from the right) using a mask Jan 27, 2016 · We can use bitwise XOR ^ operator to swap to numbers. Output: 21. Syntax: swap(a, b) Parameters: The function accepts two mandatory parameters a and b which are to be swapped. &nbsp;Example 1:Input:X = 47P1 = 1P2 = 5N = 3Output:&nbsp;227. Apr 2, 2012 · If it means same pointer variable - then yes, you can't swap same var - XOR swap must be applied to two variables which are stored at different memory addresses. Other bits can be filled randomly. For example, if the x = 258 ( 00000001 00000010 ) after the swap, x will be 513 ( 00000010 00000001 ). For example, 100 is represented as 01100100 in a byte (or 8 bits). Similarly subtract (i+1)th bit and add it to ith index. Otherwise, it is unset. for example say I have a char arr[1000] whose arr[0] = 00100011 and arr[999] = 11010110, I want to swap arr[0] and arr[999] and in addition reverse the bits in each Oct 5, 2014 · Your naming is a bit terse. First shift the bit in given position to right-end. 16 bit swap it's just a bit-rotate. These algorithms utilize bitwise operators like AND, OR, XOR, shift operators, etc. g. In C, the following 6 operators are bitwise operators (also known as bit operators as they work at the bit-level). Bitwise XOR operator evaluates each bit of the result to 1 if corresponding bits of the operands are different otherwise evaluates 0. Either create mask2 (0x55555555) for even bits or right shift the mask to extract it. The number 0x55555555 is a 32 bit number with all odd bits set as 1 and all even bits as 0. I wanted to replace bit/bits (more than one) in a 32/64 bit data field without affecting other bits. Step 1: Enter two numbers from console. I had an interview yesterday. The function you posted still isn't quite right, but I think I see where you (it) was going with it. Stack stack = new Stack(); Bit[] bits = new Bit[] { 0, 0, 1, 0, 0, 0, 0, 0 }; Given a byte (an integer number of 8 bits) and we have to swap its any two bits using C program. In other words, we need to swap the bits at even positions with the bits at odd positions. According to 1010, we need to swap the 1st position with 6th, and 3rd position with 4th Oct 12, 2010 · Write a function that takes an unsigned short int (2 bytes) and swaps the bytes. secondNumber = firstNumber XOR secondNumber = 00000011 XOR 00001010 = 00001001. Because of the declaration of swap, the Mar 22, 2015 · The question was not "how to implement a swap macro", it's "how to implement a swap macro in C". Hot Network Questions Mar 15, 2018 · Introduction Some times you need to swap bytes. Apr 9, 2010 · You may use a table that store the reverse value of each byte with (i * 0x0202020202ULL & 0x010884422010ULL) % 0x3ff, initialized through a lambda (you will need to compile it with g++ -std=c++1z since it only works since C++17), and then return the value in the table will give you the accordingly reversed bit: Need to swap the bits as: 40 in Hex => 64 in Dec => 0100. 5:6 --- 0 0 0 1 1 0 1 1 Now, when I read the register, I get say value 0x146 (0001 0 10 0 0110). When these masked bits are shifted by 2 bits and combined, the result is: Dec 30, 2018 · C program to set/clear (low/high) bits of a number; C program to swap two numbers using bitwise operator; C program to Count the Number of Trailing Zeroes in an Integer; C program to find the Highest Bit Set for any given Integer; C program to check if all the bits of a given integer is one (1) C program to count number of bits set to 1 in an With the help of various sources, I have written some SwapBytes methods in my binary reader class that swap endian in ushort, uint, and ulong, all using bitwise operations all in raw C# with no need for any unsafe code. For example, consider the following byte: AB The output should be: BA. temp = x & bitmask makes temp a value with 8 leading zero bits, and then the 8 bits identical to the last 8 bits of x. iIn = ((iIn>>2) & 0x33) | ((iIn<<2) & 0xCC); iIn = ((iIn>>1) & 0x55) | ((iIn<<1) & 0xAA); For swapping just two nibbles in a single byte, this is the most efficient way to do this, and it's probably faster than a lookup table in most situations. (Update While having a pointer there's no need to call the property to get the length. lg ox lj uf iu hg sq gy pv sq