src/lib/assembly/zbi/src/zbi_items.rs

// Copyright 2023 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

//! These are structures for creating the binary data for ZBI Items.

use anyhow::{bail, Result};
use zerocopy::{AsBytes, NoCell};

// LINT.IfChange

/// This is the structure for the payload for ZBI_TYPE_PLATFORM_ID items.
#[derive(AsBytes, NoCell, Debug, PartialEq)]
#[repr(C, packed)]
pub(crate) struct ZbiPlatformId {
    pub vid: u32,
    pub pid: u32,
    pub board_name: [u8; 32],
}

/// This is the structure for the payload for ZBI_TYPE_DRV_BOARD_INFO items.
#[derive(AsBytes, NoCell, Debug, PartialEq)]
#[repr(C, packed)]
pub(crate) struct ZbiBoardInfo {
    /// This is a value chosen by hardware/factory developers and is provided to
    /// driver developers via board documentation.
    pub revision: u32,
}

// LINT.ThenChange(//sdk/fidl/zbi/board.fdl)

impl ZbiPlatformId {
    pub fn new(vid: u32, pid: u32, board_name: impl Into<String>) -> Result<Self> {
        let board_name: String = board_name.into();
        if board_name.as_bytes().len() > 32 {
            bail!("board_name is too long (max 32 bytes): {}", board_name.as_bytes().len());
        }
        let mut platform_id = Self { vid, pid, board_name: [0u8; 32] };
        board_name.as_bytes().write_to_prefix(&mut platform_id.board_name);
        Ok(platform_id)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_creation() {
        let platform_id = ZbiPlatformId::new(23, 42, "some board").unwrap();
        let platform_id_bytes = platform_id.as_bytes();

        #[rustfmt::skip]
        assert_eq!(
            [
                // vid
                23u8, 0, 0, 0,

                //pid
                42, 0, 0, 0,

                //"some board"
                b's', b'o', b'm', b'e', b' ', b'b', b'o', b'a', b'r', b'd',

                //padding
                0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
            ],
            platform_id_bytes
        );
    }

    #[test]
    fn test_fails_on_long_name() {
        let result = ZbiPlatformId::new(0, 0, "this is far, far, too long of a name");
        assert!(result.is_err());
    }
}