/*
  StarForth — Steady-State Virtual Machine Runtime

  Copyright (c) 2023–2025 Robert A. James
  All rights reserved.

  This file is part of the StarForth project.

  Licensed under the StarForth License, Version 1.0 (the "License");
  you may not use this file except in compliance with the License.

  You may obtain a copy of the License at:
      https://github.com/star.4th@proton.me/StarForth/LICENSE.txt

  This software is provided "AS IS", WITHOUT WARRANTY OF ANY KIND,
  express or implied, including but not limited to the warranties of
  merchantability, fitness for a particular purpose, and noninfringement.

 See the License for the specific language governing permissions and
 limitations under the License.

 StarForth — Steady-State Virtual Machine Runtime
  Copyright (c) 2023–2025 Robert A. James
  All rights reserved.

  This file is part of the StarForth project.

  Licensed under the StarForth License, Version 1.0 (the "License");
  you may not use this file except in compliance with the License.

  You may obtain a copy of the License at:
       https://github.com/star.4th@proton.me/StarForth/LICENSE.txt

  This software is provided "AS IS", WITHOUT WARRANTY OF ANY KIND,
  express or implied, including but not limited to the warranties of
  merchantability, fitness for a particular purpose, and noninfringement.

  See the License for the specific language governing permissions and
  limitations under the License.

 */

/**
 * apic.h - Local APIC interface
 */

#ifndef STARKERNEL_APIC_H
#define STARKERNEL_APIC_H

#include "uefi.h"
#include <stdint.h>

/* Heartbeat timer vector (user-defined IRQ space starts at 0x20) */
#define APIC_TIMER_VECTOR  0x20

/* Initialize Local APIC (enables APIC, sets spurious vector) */
int apic_init(BootInfo *boot_info);

/* Send End-of-Interrupt signal */
void apic_eoi(void);

/*
 * Initialize APIC timer for periodic heartbeat.
 * @param tsc_hz     TSC frequency in Hz (for calibration)
 * @param tick_hz    Desired tick frequency (e.g., 100 = 100 Hz = 10ms period)
 * @return 0 on success, -1 on failure
 */
int apic_timer_init(uint64_t tsc_hz, uint32_t tick_hz);

/**
 * Start the APIC timer (enables periodic interrupts).
 * Call this after IDT and heartbeat handler are set up.
 */
void apic_timer_start(void);

/**
 * Stop the APIC timer (disables periodic interrupts).
 */
void apic_timer_stop(void);

/**
 * Re-arm the APIC timer at the current adaptive period (item 0.8, §26).
 * Recomputes the initial count from heartbeat_next_period_ns() and writes
 * it to the ICR; a periodic-mode ICR write restarts the countdown
 * immediately at the new value. Called once per tick from the ISR, before
 * heartbeat_tick().
 */
void apic_timer_rearm(void);

/**
 * Get the configured timer period in TSC ticks.
 */
uint64_t apic_timer_period_tsc(void);

#endif /* STARKERNEL_APIC_H */