Trait FlashBlock 

pub trait FlashBlock {
    type Error;

    // Required methods
    fn load<T>(&mut self) -> Result<Option<T>, Self::Error>
       where T: Serialize + for<'de> Deserialize<'de>;
    fn save<T>(&mut self, value: &T) -> Result<(), Self::Error>
       where T: Serialize + for<'de> Deserialize<'de>;
    fn clear(&mut self) -> Result<(), Self::Error>;
}

Operations on blocks of flash memory.

Platform crates implement this trait on their concrete flash block handle types.

Constructors and hardware wiring remain platform-specific; this trait defines the shared operation surface used by higher-level abstractions.

Features

• Type safety: hash-based type checking prevents reading data written under a different Rust type name. Trying to read a different type returns Ok(None).
• Postcard serialization: compact, no_std-friendly binary format.

This example increments a persisted boot counter and clears a separate scratch block in the same helper.

Example

use core::convert::Infallible;
use device_envoy_core::flash_block::FlashBlock;

#[derive(serde::Serialize, serde::Deserialize, Debug, Clone, Copy)]
struct BootCounter(u8);

impl BootCounter {
    const fn new(value: u8) -> Self {
        Self(value)
    }

    fn increment(self) -> Self {
        Self((self.0 + 1) % 10)
    }
}

fn update_boot_counter_and_clear_scratch(
    boot_counter_flash_block: &mut impl FlashBlock<Error = Infallible>,
    scratch_flash_block: &mut impl FlashBlock<Error = Infallible>,
) -> Result<BootCounter, Infallible> {
    // Load the typed value, defaulting to 0 when the block is empty.
    let boot_counter = boot_counter_flash_block
        .load()?
        .unwrap_or(BootCounter::new(0))
        .increment();

    // Save the updated value back to flash.
    boot_counter_flash_block.save(&boot_counter)?;

    // Clear the extra scratch block.
    scratch_flash_block.clear()?;

    Ok(boot_counter)
}

Required Associated Types

type Error

Error returned by block operations.

Required Methods

fn load<T>(&mut self) -> Result<Option<T>, Self::Error>

where T: Serialize + for<'de> Deserialize<'de>,

Load a typed value from this block.

Returns Ok(None) when the block is empty or contains a different type.

See the FlashBlock trait documentation for usage examples.

fn save<T>(&mut self, value: &T) -> Result<(), Self::Error>

where T: Serialize + for<'de> Deserialize<'de>,

Save a typed value to this block.

See the FlashBlock trait documentation for usage examples.

fn clear(&mut self) -> Result<(), Self::Error>

Clear this block.

See the FlashBlock trait documentation for usage examples.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors