core.cxxm

/// SPDX-License-Identifier: Apache-2.0
/// @file zxfoundation/sys/timer.cxxm
/// @brief Generic kernel timer subsystem — per-CPU min-heap with clock comparator arming.
 
export module zxfoundation.sys.timer.core;
import zxfoundation.sys.timer.types;
import zxfoundation.base.types;
import arch.s390x.cpu.irq;
import lib.error;
import std;
 
export {
 
namespace zxfoundation::sys::timer {
 
    /// @brief Convert nanoseconds to TOD clock units.
    [[nodiscard]] constexpr auto ns_to_tod(u64 ns) noexcept -> u64 {
        return static_cast<u64>(
            (static_cast<u128>(ns) * 4096ULL) / 1000ULL);
    }
 
    /// @brief Convert TOD clock units to nanoseconds.
    [[nodiscard]] constexpr auto tod_to_ns(u64 tod) noexcept -> u64 {
        return static_cast<u64>(
            (static_cast<u128>(tod) * 1000ULL) / 4096ULL);
    }
 
    /// @brief Initialize the timer subsystem on an application processor.
    constexpr auto init_ap(u16 cpu_id) noexcept -> void { discard_value cpu_id; }
 
    /// @brief Add a timer to the current CPU's heap and arm the clock comparator.
    [[nodiscard]] auto timer_add(kernel_timer& t) noexcept
        -> std::expected<void, lib::kernel_error>;
 
    /// @brief Cancel an armed timer.
    [[nodiscard]] auto timer_cancel(kernel_timer& t) noexcept
        -> std::expected<void, lib::kernel_error>;
 
    /// @brief Clock comparator interrupt handler.
    auto timer_interrupt() noexcept -> void;
 
    /// @brief Initialize the timer subsystem on the BSP (CPU 0).
    auto init() noexcept -> void;
 
} // namespace zxfoundation::sys::timer
 
} // end export