stdendian.h header providing cross-platform endian macros and endian conversion functions.
This header defines endian macros referenced here: http://austingroupbugs.net/view.php?id=162
BYTE_ORDER- macro shall have a value equal to one of the_ENDIAN macros in this header.
LITTLE_ENDIAN- the host byte order is from least significant to most significant.
BIG_ENDIAN- the host byte order is from most significant to least significant.
This header also defines several byte-swap interfaces, some that map directly to the host byte swap intrinsics and some sensitive to the host endian representation, performing a swap only if the host representation differs from the chosen representation.
These interfaces swap the byte order of words and map to host byte swap intrinsics.
uint16_t bswap16(uint16_t x);uint32_t bswap32(uint32_t x);uint64_t bswap64(uint32_t x);
Simplified endian sensitive interfaces designed to remove duplication. These interfaces require wrapping loads or stores with indication of the representation. This style has been adopted by cryptographers because it makes code and algorithms easier to read and understand.
The simplified interface provides functions for a single byte, which are a functional no-op. They are provided for symmetry, as these functions are often passed as template arguments for IO helpers.
uint8_t be8(uint8_t x);uint16_t be16(uint16_t x);uint32_t be32(uint32_t x);uint64_t be64(uint32_t x);
uint8_t le8(uint8_t x);uint16_t le16(uint16_t x);uint32_t le32(uint32_t x);uint64_t le64(uint32_t x);
Traditional BSD interface with duplication. These are traditional interfaces that have redundant directionality. The redundancy can make it more complex to read and understand code versus simply indicating representation. These interfaces are retained for compatibility.
uint16_t htobe16(uint16_t x) { return be16(x); }uint16_t htole16(uint16_t x) { return le16(x); }uint16_t be16toh(uint16_t x) { return be16(x); }uint16_t le16toh(uint16_t x) { return le16(x); }
uint32_t htobe32(uint32_t x) { return be32(x); }uint32_t htole32(uint32_t x) { return le32(x); }uint32_t be32toh(uint32_t x) { return be32(x); }uint32_t le32toh(uint32_t x) { return le32(x); }
uint64_t htobe64(uint64_t x) { return be64(x); }uint64_t htole64(uint64_t x) { return le64(x); }uint64_t be64toh(uint64_t x) { return be64(x); }uint64_t le64toh(uint64_t x) { return le64(x); }