/*
 * Copyright (c) 2017 Richard Braun.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef _KERN_THREAD_I_H
#define _KERN_THREAD_I_H

#include <kern/cpumap.h>
#include <kern/list.h>
#include <kern/macros.h>
#include <kern/param.h>
#include <kern/types.h>
#include <machine/atomic.h>
#include <machine/tcb.h>

struct thread_runq;
struct thread_fs_runq;

/*
 * Thread flags.
 */
#define THREAD_YIELD    0x1UL /* Must yield the processor ASAP */
#define THREAD_DETACHED 0x2UL /* Resources automatically released on exit */

/*
 * Thread states.
 *
 * Threads in the running state may not be on a run queue if they're being
 * awaken.
 */
#define THREAD_RUNNING  0
#define THREAD_SLEEPING 1
#define THREAD_DEAD     2

/*
 * Scheduling data for a real-time thread.
 */
struct thread_rt_data {
    struct list node;
    unsigned short time_slice;
};

/*
 * Scheduling data for a fair-scheduling thread.
 */
struct thread_fs_data {
    struct list group_node;
    struct list runq_node;
    struct thread_fs_runq *fs_runq;
    unsigned long round;
    unsigned short weight;
    unsigned short work;
};

/*
 * Common scheduling data.
 */
struct thread_sched_data {
    unsigned char sched_policy;
    unsigned char sched_class;
    unsigned short priority;
};

/*
 * Maximum number of thread-specific data keys.
 */
#define THREAD_KEYS_MAX 4

/*
 * Thread structure.
 *
 * Thread members are normally protected by the lock of the run queue they're
 * associated with. Thread-local members are accessed without synchronization.
 */
struct thread {
    struct tcb tcb;

    /* Flags must be changed atomically */
    unsigned long flags;

    /* Sleep/wakeup synchronization members */
    struct thread_runq *runq;
    unsigned short state;

    /* Thread-local members */
    unsigned short preempt;
    unsigned short pinned;
    unsigned short llsync_read;

    /* Processors on which this thread is allowed to run */
    struct cpumap cpumap;

    /* Scheduling data */
    struct thread_sched_data sched_data;

    /* Class specific scheduling data */
    union {
        struct thread_rt_data rt_data;
        struct thread_fs_data fs_data;
    };

    /*
     * Thread-specific data should only be used by architecture-dependent code.
     * For machine-independent code, new member variables should be added.
     *
     * TODO move those to the TCB and remove.
     */
    void *tsd[THREAD_KEYS_MAX];

    /* Members related to termination */
    struct mutex join_lock;
    struct condition join_cond;
    int exited;

    /* Read-only members */
    struct task *task;
    struct list task_node;
    void *stack;
    char name[THREAD_NAME_SIZE];
    void (*fn)(void *);
    void *arg;
} __aligned(CPU_L1_SIZE);

#define THREAD_ATTR_DETACHED 0x1

/*
 * Flag access functions.
 */

static inline void
thread_set_flag(struct thread *thread, unsigned long flag)
{
    atomic_or_ulong(&thread->flags, flag);
}

static inline void
thread_clear_flag(struct thread *thread, unsigned long flag)
{
    atomic_and_ulong(&thread->flags, ~flag);
}

static inline int
thread_test_flag(struct thread *thread, unsigned long flag)
{
    barrier();
    return ((thread->flags & flag) != 0);
}

#endif /* _KERN_THREAD_I_H */