What is 4 byte aligned address?
For instance, if the address of a data is 12FEECh (1244908 in decimal), then it is 4-byte alignment because the address can be evenly divisible by 4. (You can divide it by 2 or 1, but 4 is the highest number that is divisible evenly.) CPU does not read from or write to memory one byte at a time.
How do you align 16 bytes?
Each byte is 8 bits, so to align on a 16 byte boundary, you need to align to each set of two bytes. Similarly, memory aligned on a 32 bit (4 byte) boundary would have a memory address that’s a multiple of four, because you group four bytes together to form a 32 bit word.
What does it mean to be 8 byte aligned?
An object that is “8 bytes aligned” is stored at a memory address that is a multiple of 8. Many CPUs will only load some data types from aligned locations; on other CPUs such access is just faster.
What does memory aligned mean?
Alignment refers to the arrangement of data in memory, and specifically deals with the issue of accessing data as proper units of information from main memory. First we must conceptualize main memory as a contiguous block of consecutive memory locations. Each location contains a fixed number of bits.
What does Alignas mean in C++?
The alignas type specifier is a portable, C++ standard way to specify custom alignment of variables and user defined types. The alignof operator is likewise a standard, portable way to obtain the alignment of a specified type or variable.
How do I know if my address is 16 byte aligned?
If the address is 16 byte aligned, these must be zero. Notice the lower 4 bits are always 0. The cryptic if statement now becomes very clear and intuitive. We simply mask the upper portion of the address, and check if the lower 4 bits are zero.
Why do we align data?
Alignment helps the CPU fetch data from memory in an efficient manner: less cache miss/flush, less bus transactions etc. Some memory types (e.g. RDRAM, DRAM etc.) need to be accessed in a structured manner (aligned “words” and in “burst transactions” i.e. many words at one time) in order to yield efficient results.
What is the purpose of Alignas?
https://www.youtube.com/watch?v=RwtquEh5SUo