app_common

Shared header-only utilities for the Mcwhirter / bannister / brasher fleet. Single source of truth for code that used to be hand-copied (and had drifted) between the three repos.

Contents

• inc/app_utils.hpp — byte/span casts (as_bytes), overloads, deferrer, to_mac_string (only when the toolchain has <format>; guarded by __cpp_lib_format).
• inc/app_clock.hpp — monotonic microsecond TrivialClock. The only OS-specific code in this repo: now() is k_uptime_ticks() on Zephyr and esp_timer_get_time() on ESP-IDF, selected by __ZEPHYR__ / ESP_PLATFORM.
• inc/app_clock_instant.hpp — Instant, Rust-style elapsed-time helper on top of clock_t. Pure std::chrono, no OS dependency.

Everything requires C++23 (all consumers build with -std=gnu++23 / CONFIG_STD_CPP2B).

Consuming

ESP-IDF: add as a git submodule under components/app_common. The root CMakeLists.txt registers the component; add app_common to your REQUIRES.

Zephyr: add as a git submodule (e.g. modules/app_common) and append it to EXTRA_ZEPHYR_MODULES in the application CMakeLists before find_package(Zephyr). The include directory is registered globally; targets app_common / app_utils / app_utils_clock exist for explicit linking.

Rules

• Nothing platform-specific beyond the app_clock.hpp seam. If a helper needs ESP-IDF or Zephyr APIs, it belongs in the consuming repo, not here.
• Never copy these headers back into a consumer repo. Bump the submodule.