overlay_macro

A proc-macro for generating a struct which can be overlaid. See the documentation for usage and examples.

Usage

#[overlay]
#[derive(Clone, Debug)]
pub struct InquiryCommand {
    #[overlay(byte=0, bits=0..8)]
    pub op_code: u8,

    #[overlay(byte=1)]
    pub enable_vital_product_data: bool,

    #[overlay(byte=2, bits=0..=7)]
    pub page_code: u8,

    #[overlay(bytes=3..=4, bits=0..=7)]
    pub allocation_length: u16,

    ...
}

This will create a wrapper struct around an array of bytes, with generated getters and setters for each "field", accessing the bytes/bits at the given offsets.

Todo

• Support for nested structs
• Support for individual fields larger than u32 ?
• compile_error!() / remove unwrap / expect
  • And use trybuild
  • Emit a fake struct to avoid further errors about it
• Permit missing start/end in byte/bit ranges
• Upgrade to syn 2.0
• Don't drop all other attrs on enum members
• Turn off all syn (crate dep) features (except necessary)