kernel/arch/i386/task.c

   1 /*
   2  *  ZeX/OS
   3  *  Copyright (C) 2008  Tomas 'ZeXx86' Jedrzejek (zexx86@zexos.org)
   4  *
   5  *  This program is free software: you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation, either version 3 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19
  20 #include <task.h>
  21
  22
  23 unsigned arch_task_init (task_t *task, unsigned entry)
  24 {
  25         (void) setjmp (task->state);
  26         // ...especially the stack pointer
  27         unsigned adr = (unsigned) (task->stacks + USER_STACK_SIZE);
  28         task->state[0].JMPBUF_SP = adr;
  29         // ...and program counter
  30         task->state[0].JMPBUF_IP = entry;
  31         // set EFLAGS value to enable interrupts
  32         task->state[0].JMPBUF_FLAGS = 0x200;
  33
  34         return 1;
  35 }
  36
  37 unsigned arch_task_set (task_t *task)
  38 {
  39         return setjmp (task->state);
  40 }
  41
  42 unsigned arch_task_switch (task_t *task)
  43 {
  44         /* fake long jump (register switch) to task function */
  45         longjmp (task->state, 1);
  46
  47         return 1;
  48 }