Castflip is a library for encoding and decoding numeric variables, arrays and structures in little-endian and big-endian.
In this crate, the term encast means decoding a number of bytes to
one or more values, the term decast means encoding one or more
variables to a number of bytes, and the term endian-flip means
flipping the endianness of value(s).
Here we show an example below. For more examples and documentation, please see https://docs.rs/castflip/.
In the example below, method encastf decodes bytes in bytes1 in
big-endian (BE) to variable udp_hdr2 of type UdpHdr. Then,
method decastf encodes the resulting value in udp_hdr2 to bytes in
big-endian (BE) and stores them in bytes3.
```rust use castflip::{Cast, Flip, EncastMem, DecastMem, BE};
struct UdpHdr { // UDP: https://www.rfc-editor.org/rfc/rfc768.txt sport: u16, // UDP Source Port dport: u16, // UDP Destination Port len: u16, // UDP Length sum: u16, // UDP Checksum }
// Input data: UDP header (8 bytes) let bytes1: [u8; 8] = [0xC3, 0xC9, 0x00, 0x35, 0x00, 0x32, 0x82, 0x3F];
// Decode bytes bytes1 to variable udp_hdr2.
let udp_hdr2 = bytes1.encastf::
// Encode the resulting UDP header udp_hdr2 to bytes bytes3.
let mut bytes3 = [0u8; 8];
let bytes3size = bytes3.decastf::
// Check the results. asserteq!(udphdr2.sport, 0xC3C9); // = 50121 asserteq!(udphdr2.dport, 0x0035); // = 53 (DNS) asserteq!(udphdr2.len, 0x0032); // = 50 asserteq!(udphdr2.sum, 0x823F); asserteq!(bytes3size, 8); assert_eq!(bytes3, bytes1); ```
In the example above, #[derive(Cast)] makes the value of UdpHdr
encastable / decastable, and #[derive(Flip)] makes the value
of UdpHdr endian-flippable.
Trait EncastMem provides methods to encast from memory, and
trait DecastMem provides methods to decast to memory. The
generic type parameters of their methods can be omitted where the Rust
compiler can infer them. Their methods whose names end with 'f' flip
the endianness of the results. The endianness of bytes is specified
by their argument. BE is an alias of Endian::Big, which
means Big-Endian.
In addition to these traits, this crate has trait EncastIO providing
methods to encast from I/O, and trait DecastIO providing methods
to decast to I/O.
Note: [UDP] is one of the fundamental protocols in the internet protocol suite.