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// http://hosted.cjmovie.net/TutMultitask.htm
//
//
#include "kernel.h"
#include "lib/logger/log.h" // logger facilities
#include "lib/buffer/ringbuffer.h"
#include "mem.h"
#include "timer.h"
#include "console.h"
#include "x86.h"
#include "syscalls.h"
#include "fs/fs.h"
#include "fs/ext2.h"
#define FOOLOS_MODULE_NAME "task"
#define MAX_TASKS 10
static volatile int current_task=-2;
static volatile struct task_list_struct
{
int parent;
bool active;
uint32_t esp; // stack pointer of the task;
uint32_t vmem; // number of virtual memory table to switch to
}volatile task_list[MAX_TASKS];
int add_task(uint32_t esp, uint32_t vmem)
{
for(int i=0;i<MAX_TASKS;i++)
{
if(task_list[i].active!=true)
{
task_list[i].parent=current_task;
task_list[i].vmem=vmem;
task_list[i].esp=esp;
task_list[i].active=true;
return i;
}
}
panic(FOOLOS_MODULE_NAME,"out of task slots!");
}
// this gets called by our clock interrupt regularly!
uint32_t task_switch_next(uint32_t oldesp)
{
timer_tick();
if(current_task==-2)return oldesp;
task_list[current_task].esp=oldesp;
for(int i=0;i<MAX_TASKS;i++)
{
int pid=(current_task+1+i)%MAX_TASKS; // schedule round robin style
if(task_list[pid].active)
{
// log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"switch from %d to pid: %d (0x%08X) vmem: %d ", current_task,pid,task_list[pid].esp,task_list[pid].vmem);
current_task=pid;
vmem_set_dir(task_list[pid].vmem);
return task_list[pid].esp;
}
}
return oldesp;
}
uint32_t task_fork(uint32_t oldesp)
{
return add_task(oldesp,vmem_new_space_dir());
}
// init task (root of all other tasks / processes) //
void task_init()
{
// this is our main task on slot 0
task_list[0].active=true;
task_list[0].vmem=0;
task_list[0].esp = 0; // will be set by next task_switch_next() call.
current_task=0;
static char *argv[]={"/bin/foolshell",NULL};
static char *env[]={"PATH=/bin","PWD=/home/miguel","PS1=$ ",NULL};
syscall_execve("/bin/init",argv,env);
}
int task_get_current_pid()
{
return current_task;
}
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