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/*
 * Copyright (C) 2001-2004 Jakub Jermar
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <proc/scheduler.h>
#include <proc/thread.h>
#include <proc/task.h>
#include <mm/heap.h>
#include <mm/frame.h>
#include <mm/page.h>
#include <arch/asm.h>
#include <arch.h>
#include <synch/synch.h>
#include <synch/spinlock.h>
#include <synch/waitq.h>
#include <synch/rwlock.h>
#include <cpu.h>
#include <func.h>
#include <context.h>
#include <list.h>
#include <typedefs.h>
#include <time/clock.h>
#include <list.h>
#include <config.h>
#include <arch/interrupt.h>
#include <smp/ipi.h>
#include <arch/faddr.h>
#include <arch/atomic.h>
#include <memstr.h>

char *thread_states[] = {"Invalid", "Running", "Sleeping", "Ready", "Entering", "Exiting"}; /**< Thread states */

SPINLOCK_INITIALIZE(threads_lock);  /**< Lock protecting threads_head list. For locking rules, see declaration thereof. */
link_t threads_head;            /**< List of all threads. */

SPINLOCK_INITIALIZE(tidlock);
__u32 last_tid = 0;


/** Thread wrapper
 *
 * This wrapper is provided to ensure that every thread
 * makes a call to thread_exit() when its implementing
 * function returns.
 *
 * interrupts_disable() is assumed.
 *
 */
static void cushion(void)
{
    void (*f)(void *) = THREAD->thread_code;
    void *arg = THREAD->thread_arg;

    /* this is where each thread wakes up after its creation */
    before_thread_runs();

    spinlock_unlock(&THREAD->lock);
    interrupts_enable();

    f(arg);
    thread_exit();
    /* not reached */
}


/** Initialize threads
 *
 * Initialize kernel threads support.
 *
 */
void thread_init(void)
{
    THREAD = NULL;
    nrdy = 0;
    list_initialize(&threads_head);
}


/** Make thread ready
 *
 * Switch thread t to the ready state.
 *
 * @param t Thread to make ready.
 *
 */
void thread_ready(thread_t *t)
{
    cpu_t *cpu;
    runq_t *r;
    ipl_t ipl;
    int i, avg, send_ipi = 0;

    ipl = interrupts_disable();

    spinlock_lock(&t->lock);

    i = (t->priority < RQ_COUNT -1) ? ++t->priority : t->priority;
    
    cpu = CPU;
    if (t->flags & X_WIRED) {
        cpu = t->cpu;
    }
    spinlock_unlock(&t->lock);
    
    /*
     * Append t to respective ready queue on respective processor.
     */
    r = &cpu->rq[i];
    spinlock_lock(&r->lock);
    list_append(&t->rq_link, &r->rq_head);
    r->n++;
    spinlock_unlock(&r->lock);

    atomic_inc(&nrdy);
    avg = nrdy / config.cpu_active;

    spinlock_lock(&cpu->lock);
    if ((++cpu->nrdy) > avg) {
        /*
         * If there are idle halted CPU's, this will wake them up.
         */
        ipi_broadcast(VECTOR_WAKEUP_IPI);
    }   
    spinlock_unlock(&cpu->lock);

    interrupts_restore(ipl);
}


/** Create new thread
 *
 * Create a new thread.
 *
 * @param func  Thread's implementing function.
 * @param arg   Thread's implementing function argument.
 * @param task  Task to which the thread belongs.
 * @param flags Thread flags.
 *
 * @return New thread's structure on success, NULL on failure.
 *
 */
thread_t *thread_create(void (* func)(void *), void *arg, task_t *task, int flags)
{
    thread_t *t;
    __address frame_ks, frame_us = NULL;

    t = (thread_t *) malloc(sizeof(thread_t));
    if (t) {
        ipl_t ipl;
    
        spinlock_initialize(&t->lock, "thread_t_lock");
    
        frame_ks = frame_alloc(FRAME_KA, ONE_FRAME);
        if (THREAD_USER_STACK & flags) {
            frame_us = frame_alloc(FRAME_KA, ONE_FRAME);
        }

        ipl = interrupts_disable();
        spinlock_lock(&tidlock);
        t->tid = ++last_tid;
        spinlock_unlock(&tidlock);
        interrupts_restore(ipl);
        
        memsetb(frame_ks, THREAD_STACK_SIZE, 0);
        link_initialize(&t->rq_link);
        link_initialize(&t->wq_link);
        link_initialize(&t->th_link);
        link_initialize(&t->threads_link);
        t->kstack = (__u8 *) frame_ks;
        t->ustack = (__u8 *) frame_us;
        
        context_save(&t->saved_context);
        context_set(&t->saved_context, FADDR(cushion), (__address) t->kstack, THREAD_STACK_SIZE);
        
        the_initialize((the_t *) t->kstack);

        ipl = interrupts_disable();
        t->saved_context.ipl = interrupts_read();
        interrupts_restore(ipl);
        
        t->thread_code = func;
        t->thread_arg = arg;
        t->ticks = -1;
        t->priority = -1;       /* start in rq[0] */
        t->cpu = NULL;
        t->flags = 0;
        t->state = Entering;
        t->call_me = NULL;
        t->call_me_with = NULL;
        
        timeout_initialize(&t->sleep_timeout);
        t->sleep_queue = NULL;
        t->timeout_pending = 0;
        
        t->rwlock_holder_type = RWLOCK_NONE;
        
        t->task = task;
        
        t->fpu_context_exists=0;
        t->fpu_context_engaged=0;
        
        /*
         * Register this thread in the system-wide list.
         */
        ipl = interrupts_disable();     
        spinlock_lock(&threads_lock);
        list_append(&t->threads_link, &threads_head);
        spinlock_unlock(&threads_lock);

        /*
         * Attach to the containing task.
         */
        spinlock_lock(&task->lock);
        list_append(&t->th_link, &task->th_head);
        spinlock_unlock(&task->lock);

        interrupts_restore(ipl);
    }

    return t;
}


/** Make thread exiting
 *
 * End current thread execution and switch it to the exiting
 * state. All pending timeouts are executed.
 *
 */
void thread_exit(void)
{
    ipl_t ipl;

restart:
    ipl = interrupts_disable();
    spinlock_lock(&THREAD->lock);
    if (THREAD->timeout_pending) { /* busy waiting for timeouts in progress */
        spinlock_unlock(&THREAD->lock);
        interrupts_restore(ipl);
        goto restart;
    }
    THREAD->state = Exiting;
    spinlock_unlock(&THREAD->lock);
    scheduler();
}


/** Thread sleep
 *
 * Suspend execution of the current thread.
 *
 * @param sec Number of seconds to sleep.
 *
 */
void thread_sleep(__u32 sec)
{
    thread_usleep(sec*1000000);
}


/** Thread usleep
 *
 * Suspend execution of the current thread.
 *
 * @param usec Number of microseconds to sleep.
 *
 */ 
void thread_usleep(__u32 usec)
{
    waitq_t wq;
                  
    waitq_initialize(&wq);

    (void) waitq_sleep_timeout(&wq, usec, SYNCH_NON_BLOCKING);
}


/** Register thread out-of-context invocation
 *
 * Register a function and its argument to be executed
 * on next context switch to the current thread.
 *
 * @param call_me      Out-of-context function.
 * @param call_me_with Out-of-context function argument.
 *
 */
void thread_register_call_me(void (* call_me)(void *), void *call_me_with)
{
    ipl_t ipl;
    
    ipl = interrupts_disable();
    spinlock_lock(&THREAD->lock);
    THREAD->call_me = call_me;
    THREAD->call_me_with = call_me_with;
    spinlock_unlock(&THREAD->lock);
    interrupts_restore(ipl);
}