/*****************************************************************************************
 Copyright (c) 2002-2004 The UbixOS Project
 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, the following disclaimer and the list of authors.  Redistributions in binary
 form must reproduce the above copyright notice, this list of conditions, the following
 disclaimer and the list of authors in the documentation and/or other materials provided
 with the distribution. Neither the name of the UbixOS Project nor the names of its
 contributors may be used to endorse or promote products derived from this software
 without specific prior written permission.

 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER OR CONTRIBUTORS 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.

 $Id: sched.c 164 2016-01-20 00:04:02Z reddawg $

 *****************************************************************************************/

#include <ubixos/sched.h>
#include <ubixos/kpanic.h>
#include <ubixos/spinlock.h>
#include <ubixos/endtask.h>
#include <vfs/mount.h>
#include <lib/kmalloc.h>
#include <lib/kprintf.h>
#include <vmm/vmm.h>
#include <sys/gdt.h>
#include <sys/idt.h>
#include <sys/kern_descrip.h>
#include <isa/8259.h>
#include <string.h>
#include <assert.h>

#include <ubixos/spinlock.h>

#define STACK_ADDR 0xC800000

static kTask_t *taskList = 0x0;
static kTask_t *delList = 0x0;
static uint32_t nextID = 1;

kTask_t *_current = 0x0;
kTask_t *_usedMath = 0x0;

static struct spinLock schedulerSpinLock = SPIN_LOCK_INITIALIZER;

/************************************************************************

 Function: int sched_init()

 Description: This function is used to enable the kernel scheduler

 Notes:

 02/20/2004 - Approved for quality

 ************************************************************************/

int sched_init() {
  taskList = (kTask_t *) kmalloc( sizeof(kTask_t) );
  if ( taskList == 0x0 )
    kpanic( "Unable to create task list" );

  taskList->id = nextID++;

  /* Print out information on scheduler */
  kprintf( "sched0 - Address: [0x%X]\n", taskList );

  /* Return so we know everything went well */
  return (0x0);
}

void sched() {
  uint32_t memAddr = 0x0;
  kTask_t *tmpTask = 0x0;
  kTask_t *delTask = 0x0;

  if ( spinTryLock( &schedulerSpinLock ) )
    return;

  tmpTask = _current->next;
  //outportByte(0xE9,_current->id + '0');
  schedStart:

  /* Yield the next task from the current prio queue */
  for ( ; tmpTask != 0x0; tmpTask = tmpTask->next ) {
    if ( tmpTask->state > 0x0 ) {
      _current = tmpTask;
      if ( _current->state == FORK )
        _current->state = READY;
      break;
    }
    else if ( tmpTask->state == DEAD ) {
      delTask = tmpTask;
      tmpTask = tmpTask->next;
      sched_deleteTask( delTask->id );
      sched_addDelTask( delTask );
      goto schedStart;
    }
  }

  /* Finished all the tasks, restarting the list */
  if ( 0x0 == tmpTask ) {
    tmpTask = taskList;
    goto schedStart;
  }

  if ( _current->state > 0x0 ) {

    if ( _current->oInfo.v86Task == 0x1 )
      irqDisable( 0x0 );

    asm("cli");

    memAddr = (uint32_t) & (_current->tss);
    ubixGDT[4].descriptor.baseLow = (memAddr & 0xFFFF);
    ubixGDT[4].descriptor.baseMed = ((memAddr >> 16) & 0xFF);
    ubixGDT[4].descriptor.baseHigh = (memAddr >> 24);
    ubixGDT[4].descriptor.access = '\x89';

   // memAddr = STACK_ADDR; //(uint32_t) & (_current->tss);
    ubixGDT[10].descriptor.baseLow = (STACK_ADDR & 0xFFFF);
    ubixGDT[10].descriptor.baseMed = ((STACK_ADDR >> 16) & 0xFF);
    ubixGDT[10].descriptor.baseHigh = (STACK_ADDR >> 24);
/*
    ubixGDT[10].descriptor.access = '\x89';
*/

    spinUnlock( &schedulerSpinLock );

    asm("sti");
    asm("ljmp $0x20,$0\n");
  }
  else {
    spinUnlock( &schedulerSpinLock );
  }

  return;
}

kTask_t *schedNewTask() {
  int i = 0;

  kTask_t *tmpTask = (kTask_t *) kmalloc( sizeof(kTask_t) );

  struct file *fp = 0x0;

  if ( tmpTask == 0x0 )
    kpanic( "Error: schedNewTask() - kmalloc failed trying to initialize a new task struct\n" );

  memset( tmpTask, 0x0, sizeof(kTask_t) );

  /* Filling in tasks attrs */
  tmpTask->usedMath = 0x0;
  tmpTask->state = NEW;

  /* HACK */

  for ( i = 0; i < 3; i++ ) {
    fp = (void *) kmalloc( sizeof(struct file) );
    //kprintf("DB: [0x%X]\n", (uint32_t) fp);
    tmpTask->td.o_files[i] = (void *) fp;
    fp->f_flag = 0x4;
  }

  spinLock( &schedulerSpinLock );
  tmpTask->id = nextID++;
  tmpTask->next = taskList;
  tmpTask->prev = 0x0;
  taskList->prev = tmpTask;
  taskList = tmpTask;

  spinUnlock( &schedulerSpinLock );

  return (tmpTask);
}

int sched_deleteTask( pidType id ) {
  kTask_t *tmpTask = 0x0;

  /* Checking each task from the prio queue */
  for ( tmpTask = taskList; tmpTask != 0x0; tmpTask = tmpTask->next ) {
    if ( tmpTask->id == id ) {
      if ( tmpTask->prev != 0x0 )
        tmpTask->prev->next = tmpTask->next;
      if ( tmpTask->next != 0x0 )
        tmpTask->next->prev = tmpTask->prev;
      if ( taskList == tmpTask )
        taskList = tmpTask->next;

      return (0x0);
    }
  }
  return (0x1);
}

int sched_addDelTask( kTask_t *tmpTask ) {
  tmpTask->next = delList;
  tmpTask->prev = 0x0;
  if ( delList != 0x0 )
    delList->prev = tmpTask;
  delList = tmpTask;
  return (0x0);
}

kTask_t *sched_getDelTask() {
  kTask_t *tmpTask = 0x0;

  if ( delList == 0x0 )
    return (0x0);

  tmpTask = delList;
  delList = delList->next;
  return (tmpTask);
}

kTask_t *schedFindTask( uint32_t id ) {
  kTask_t *tmpTask = 0x0;

  for ( tmpTask = taskList; tmpTask; tmpTask = tmpTask->next ) {
    if ( tmpTask->id == id )
      return (tmpTask);
  }

  return (0x0);
}

/************************************************************************

 Function: void schedEndTask()

 Description: This function will end a task

 Notes:

 02/20/2004 - Approved for quality

 ************************************************************************/
void schedEndTask( pidType pid ) {
  endTask( _current->id );
  sched_yield();
}

/************************************************************************

 Function: int schedEndTask()

 Description: This function will yield a task

 Notes:

 02/20/2004 - Approved for quality

 ************************************************************************/

void sched_yield() {
  sched();
}

/*
 asm(
 ".globl sched_yield \n"
 "sched_yield:       \n"
 "  cli              \n"
 "  call sched       \n"
 );
 */

/************************************************************************

 Function: int sched_setStatus(pidType pid,tState state)

 Description: Change the tasks status

 Notes:

 ************************************************************************/
int sched_setStatus( pidType pid, tState state ) {
  kTask_t *tmpTask = schedFindTask( pid );
  if ( tmpTask == 0x0 )
    return (0x1);
  tmpTask->state = state;
  return (0x0);
}

/***
 END
 ***/