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1113 palkovsky 1 
/*
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 * Copyright (C) 2006 Ondrej Palkovsky
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms, with or without
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 * modification, are permitted provided that the following conditions
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 * are met:
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 *
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 * - Redistributions of source code must retain the above copyright
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 *   notice, this list of conditions and the following disclaimer.
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 * - Redistributions in binary form must reproduce the above copyright
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 *   notice, this list of conditions and the following disclaimer in the
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 *   documentation and/or other materials provided with the distribution.
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 * - The name of the author may not be used to endorse or promote products
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 *   derived from this software without specific prior written permission.
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 *
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 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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 */
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#include <libadt/list.h>
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#include <psthread.h>
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#include <malloc.h>
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#include <unistd.h>
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#include <thread.h>
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#include <stdio.h>
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#include <kernel/arch/faddr.h>
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static LIST_INITIALIZE(ready_list);
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static void psthread_exit(void) __attribute__ ((noinline));
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static void psthread_main(void);
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/** Function to preempt to other pseudo thread without adding
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 * currently running pseudo thread to ready_list.
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 */
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void psthread_exit(void)
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{
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    psthread_data_t *pt;
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    if (list_empty(&ready_list)) {
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        /* Wait on IPC queue etc... */
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        printf("Cannot exit!!!\n");
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        _exit(0);
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    }
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    pt = list_get_instance(ready_list.next, psthread_data_t, link);
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    list_remove(&pt->link);
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    context_restore(&pt->ctx);
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}
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/** Function that is called on entry to new uspace thread */
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void psthread_main(void)
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{
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    psthread_data_t *pt = __tls_get();
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    pt->retval = pt->func(pt->arg);
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    pt->finished = 1;
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    if (pt->waiter)
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        list_append(&pt->waiter->link, &ready_list);
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    psthread_exit();
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}
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/** Schedule next userspace pseudo thread.
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 *
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 * @return 0 if there is no ready pseudo thread, 1 otherwise.
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 */
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int psthread_schedule_next(void)
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{
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    psthread_data_t *pt;
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    if (list_empty(&ready_list))
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        return 0;
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    pt = __tls_get();
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    if (!context_save(&pt->ctx))
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        return 1;
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    list_append(&pt->link, &ready_list);
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    pt = list_get_instance(ready_list.next, psthread_data_t, link);
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    list_remove(&pt->link);
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    context_restore(&pt->ctx);
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}
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/** Wait for uspace pseudo thread to finish.
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 *
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 * @param psthrid Pseudo thread to wait for.
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 *
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 * @return Value returned by the finished thread.
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 */
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int psthread_join(pstid_t psthrid)
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{
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    volatile psthread_data_t *pt, *mypt;
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    volatile int retval;
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    /* Handle psthrid = Kernel address -> it is wait for call */
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    pt = (psthread_data_t *) psthrid;
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    if (!pt->finished) {
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        mypt = __tls_get();
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        if (context_save(&((psthread_data_t *) mypt)->ctx)) {
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            pt->waiter = (psthread_data_t *) mypt;
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            psthread_exit();
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        }
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    }
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    retval = pt->retval;
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    free(pt->stack);
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    __free_tls((psthread_data_t *) pt);
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    return retval;
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}
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/**
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 * Create a userspace thread and append it to ready list.
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 *
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 * @param func Pseudo thread function.
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 * @param arg Argument to pass to func.
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 *
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 * @return 0 on failure, TLS of the new pseudo thread.
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 */
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pstid_t psthread_create(int (*func)(void *), void *arg)
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{
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    psthread_data_t *pt;
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    pt = __make_tls();
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    pt->stack = (char *) malloc(getpagesize());
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    if (!pt->stack) {
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        return 0;
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    }
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    pt->arg= arg;
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    pt->func = func;
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    pt->finished = 0;
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    pt->waiter = NULL;
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    context_save(&pt->ctx);
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    context_set(&pt->ctx, FADDR(psthread_main), pt->stack, getpagesize(), pt);
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    list_append(&pt->link, &ready_list);
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    return (pstid_t )pt;
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}