The endianness is the order or sequence of bytes of a word of digital data in computer memory. Endianness is primarily expressed as big-endian (BE) or little-endian (LE). [wiki]
- Within a byte, the order of the bits is the same for all computers (no matter how the bytes themselves are arranged). [kjell]
Big Endian
A big-endian system stores the most significant byte of a word at the smallest memory address and the least significant byte at the largest. [wiki]
Little Endian
A little-endian system stores the least-significant byte at the smallest address. [wiki]
In little-endian ordering, the data structure fields that are numbers will appear in reverse order and strings will appear in the expected order. [foren]
Bi-endianness
Bi-endianness is a feature supported by numerous computer architectures that feature switchable endianness in data fetches and stores or for instruction fetches. [wiki]
Notes [bedell]
Both big-endian and little-endian are widely used in digital electronics.
The CPU typically determines the endianness in use.
Endianness is initially an arbitrary decision by the semiconductor vendor that can have a long-term effect on a line of products. When vendors update their technology, they keep the existing endianness to help maintain backward compatibility.
- For example, the designers of the Motorola 68000 and the Intel 8086 (predecessor of the x86 family) chose their endianness in the 1970s and continue to use their respective endianness today.
Use of Endianness [bedell]
IBM’s 370 mainframes, most reduced instruction set computers RISC-based computers, and Motorola microprocessors use the big-endian approach.
Transmission Control Protocol/Internet Protocol TCP/IP also uses the big-endian approach.
- For this reason, big-endian is sometimes called network order.
On the other hand, Intel processors, DEC Alphas, and at least some programs that run on them are little-endian.
Language compilers, such as Java or FORTRAN, have to know which way the object code they develop is going to be stored.
- Converters can be used to change one kind of endian to the other when necessary.
References
[wiki] Wikipedia Contributors, “Endianness,” Wikipedia, May 07, 2022. https://en.wikipedia.org/wiki/Endianness (accessed Jun. 03, 2022).
[geeks] “Little and Big Endian Mystery – GeeksforGeeks,” GeeksforGeeks, Jul. 16, 2009. https://www.geeksforgeeks.org/little-and-big-endian-mystery/ (accessed Jun. 03, 2022).
[kjell] B. Kjell, “Big Endian and Little Endian,” Ccsu.edu, 2022. https://chortle.ccsu.edu/assemblytutorial/Chapter-15/ass15_3.html (accessed Jun. 03, 2022).
[bedell] C. Bedell, “big-endian and little-endian,” SearchNetworking, 2021. https://www.techtarget.com/searchnetworking/definition/big-endian-and-little-endian (accessed Jun. 03, 2022).
[foren] https://learning.oreilly.com/library/view/file-system-forensic/0321268172/ch10.html#ch10