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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>

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

spinlock_t threads_lock;
link_t threads_head;

static spinlock_t tidlock;
__u32 last_tid = 0;

/*
 * cushion() is provided to ensure that every thread
 * makes a call to thread_exit() when its implementing
 * function returns.
 *
 * cpu_priority_high()'d
 */
void cushion(void)
{
    void (*f)(void *) = THREAD->thread_code;
    void *arg = THREAD->thread_arg;

    /* this is where each thread wakes up after its creation */
    spinlock_unlock(&THREAD->lock);
    cpu_priority_low();

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

void thread_init(void)
{
    THREAD = NULL;
    nrdy = 0;
    spinlock_initialize(&threads_lock);
    list_initialize(&threads_head);
}

void thread_ready(thread_t *t)
{
    cpu_t *cpu;
    runq_t *r;
    pri_t pri;
    int i, avg, send_ipi = 0;

    pri = cpu_priority_high();

    spinlock_lock(&t->lock);

    i = (t->pri < RQ_COUNT -1) ? ++t->pri : t->pri;
    
    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);

    spinlock_lock(&nrdylock);
    avg = ++nrdy / config.cpu_active;
    spinlock_unlock(&nrdylock);

    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);
    
    cpu_priority_restore(pri);
}

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) {
        pri_t pri;
    
        spinlock_initialize(&t->lock);
    
        frame_ks = frame_alloc(FRAME_KA);
        if (THREAD_USER_STACK & flags) {
            frame_us = frame_alloc(0);
        }

        pri = cpu_priority_high();
        spinlock_lock(&tidlock);
        t->tid = ++last_tid;
        spinlock_unlock(&tidlock);
        cpu_priority_restore(pri);

        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);
        t->saved_context.pc = (__address) cushion;
        t->saved_context.sp = (__address) &t->kstack[THREAD_STACK_SIZE-8];

        pri = cpu_priority_high();
        t->saved_context.pri = cpu_priority_read();
        cpu_priority_restore(pri);
        
        t->thread_code = func;
        t->thread_arg = arg;
        t->ticks = -1;
        t->pri = -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;
        
        /*
         * Register this thread in the system-wide list.
         */
        pri = cpu_priority_high();      
        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);

        cpu_priority_restore(pri);
    }

    return t;
}

void thread_exit(void)
{
    pri_t pri;

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

void thread_sleep(__u32 sec)
{
        thread_usleep(sec*1000000);
}
    
/*
 * Suspend execution of current thread for usec microseconds.
 */
void thread_usleep(__u32 usec)
{
    waitq_t wq;
                  
    waitq_initialize(&wq);

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

void thread_register_call_me(void (* call_me)(void *), void *call_me_with)
{
    pri_t pri;
    
    pri = cpu_priority_high();
    spinlock_lock(&THREAD->lock);
    THREAD->call_me = call_me;
    THREAD->call_me_with = call_me_with;
    spinlock_unlock(&THREAD->lock);
    cpu_priority_restore(pri);
}