Endianness
In computing, endianness (byte-order, or endian) 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). 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. A little-endian system, in contrast, stores the least-significant byte at the smallest address.
Memory Storage
Computers store information in various sized groups of binary bits. Each group is assigned a number, called its address or index, that the computer uses to access that data.
On most modern computers, the smallest data group with an address is eight bits long and is called a byte. Larger groups comprise two or more bytes, for example, a 32-bit word contains four bytes.
Examples with the number 0x0A0B0C0D:
For little-endian: 0x0D 0x0C 0x0B 0x0A
For big-endian: 0x0A 0x0B 0x0C 0x0D
Endianness may also be used to describe the order in which the bits are transmitted over a communication channel, e.g., big-endian in a communications channel transmits the most significant bits first.
Use Cases
- Intel / AMD / ARM / RISC-V processors (CPUs) use little-endian.
- network byte order uses big-endian.
- Java byte order uses big-endian.
- PowerPC uses big-endian.