Crate base16

This is a base16 (e.g. hexadecimal) encoding and decoding library with an emphasis on performance. The API is very similar and inspired by the base64 crate’s API, however it’s less complex (base16 is much more simple than base64).

Encoding

The config options at the moment are limited to the output case (upper vs lower).

Function	Output	Allocates	Requires alloc feature
encode_upper, encode_lower	Returns a new String	Always	Yes
encode_config	Returns a new String	Always	Yes
encode_config_buf	Appends to provided String	If buffer needs to grow	Yes
encode_config_slice	Writes to provided &[u8]	Never	No

Decoding

Note that there are no config options (In the future one might be added to restrict the input character set, but it’s not clear to me that this is useful).

Function	Output	Allocates	Requires alloc feature
decode	Returns a new Vec<u8>	Always	Yes
decode_slice	Writes to provided &[u8]	Never	No
decode_buf	Appends to provided Vec<u8>	If buffer needs to grow	Yes

Features

This crate has two features, both are enabled by default and exist to allow users in no_std environments to disable various portions of .

• The "alloc" feature, which is on by default, adds a number of helpful functions that require use of the alloc crate, but not the rest of std.

  • This is no_std compatible.
  • Each function should list whether or not it requires this feature under the Availability of its documentation.

• The "std" feature, which is on by default, enables the "alloc" feature, and additionally makes DecodeError implement the std::error::Error trait.

  • Frustratingly, this trait is in std (and not in core or alloc), but not implementing it would be quite annoying for some users, so it’s kept, even though it’s what prevents us from being no_std compatible in all configurations.

Re-exports

• pub use EncConfig::*;

Enums

• DecodeError
  Represents a problem with the data we want to decode.
• EncConfig
  Configuration options for encoding. Just specifies whether or not output should be uppercase or lowercase.

Functions

• decode
  Decode bytes from base16, and return a new Vec<u8> containing the results.
• decode_buf
  Decode bytes from base16, and appends into the provided buffer. Only allocates if the buffer could not fit the data. Returns the number of bytes written.
• decode_byte
  Decode a single character as hex.
• decode_slice
  Decode bytes from base16, and write into the provided buffer. Never allocates.
• encode_byte
  Encode a single character as hex, returning a tuple containing the two encoded bytes in big-endian order – the order the characters would be in when written out (e.g. the top nibble is the first item in the tuple)
• encode_byte_l
  Convenience wrapper for base16::encode_byte(byte, base16::EncodeLower)
• encode_byte_u
  Convenience wrapper for base16::encode_byte(byte, base16::EncodeUpper)
• encode_config
  Encode input into a string using the listed config. The resulting string contains input.len() * 2 bytes.
• encode_config_buf
  Encode input into the end of the provided buffer. Returns the number of bytes that were written.
• encode_config_slice
  Write bytes as base16 into the provided output buffer. Never allocates.
• encode_lower
  Encode bytes as base16, using lower case characters for nibbles between 10 and 15 (a through f).
• encode_upper
  Encode bytes as base16, using upper case characters for nibbles between 10 and 15 (A through F).