FlagsSaver.h File Reference

Atomic two-state flag bitset with optional event-flag waiter. More...

#include <atomic>
#include <climits>
#include <cstddef>
#include <cstdint>
#include "OsAbstraction.h"
#include "OsUtility.h"

Go to the source code of this file.

Classes
struct	hf::FlagsSnapshot< kWordCount >
	Snapshot of a FlagsSaver at a point in time. More...
class	hf::FlagsReader< FlagId, kCount >
	Read-side ABC for FlagsSaver. More...
class	hf::FlagsWriter< FlagId, kCount >
	Write-side ABC for FlagsSaver. More...
class	hf::FlagsSaver< FlagId, kCount >
	Concrete two-state flag bitset. More...

Namespaces
namespace	hf

Detailed Description

Atomic two-state flag bitset with optional event-flag waiter.

Three types in one header:

• hf::FlagsReader<FlagId, kCount> — pure-virtual read-side ABC.
• hf::FlagsWriter<FlagId, kCount> — pure-virtual write-side ABC.
• hf::FlagsSaver<FlagId, kCount> — concrete impl deriving from both.

Pass an hf::FlagsReader* to consumers that may only inspect / wait, and an hf::FlagsWriter* to consumers that may only publish — keeps the apps↔middleware layering honest.

Storage

Each slot holds one bit (0 = Cleared, 1 = Set); slots are packed into std::atomic<uint64_t> words (64 slots per word). Lookups and writes are lock-free. A change to any slot bumps a 32-bit sequence counter and signals a single bit on a lazily-created OsEventFlags.

Thread-safety

• Set / Clear / IsSet / Snapshot / Seq / LastChangeMs: lock-free; safe from any task context. Not ISR-safe (FreeRTOS event-group set is not ISR-safe via this path).
• WaitForChange: backed by a FreeRTOS event group; do not call from ISR.

Allocation

No heap allocation. Storage is a fixed-size atomic word array sized at compile time. The event group is created on first use.