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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
{
bool active;
uint32_t esp; // stack pointer of the task;
uint32_t vmem; // number of virtual memory table to switch to
}task_list[MAX_TASKS];
void task_create(int pid,void(*thread)())
{
unsigned int *stack;
task_list[pid].esp = pmmngr_alloc_block();
stack = (unsigned int*)task_list[pid].esp+4095; //This makes a pointer to the stack for us
log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"new task: stack: 0x%08X thread: 0x%08X", stack, thread);
//First, this stuff is pushed by the processor
*--stack = 0x0202; //This is EFLAGS
*--stack = 0x08; //This is CS, our code segment
*--stack = (uint32_t)thread; //This is EIP
//Next, the stuff pushed by 'pusha'
*--stack = 0; //EDI
*--stack = 0; //ESI
*--stack = 0; //EBP
*--stack = 0; //Just an offset, no value
*--stack = 0; //EBX
*--stack = 0; //EDX
*--stack = 0; //ECX
*--stack = 0; //EAX
//Now these are the data segments pushed by the IRQ handler
/*
*--stack = 0x10; //DS
*--stack = 0x10; //ES
*--stack = 0x10; //FS
*--stack = 0x10; //GS
*/
task_list[pid].esp = (uint32_t)stack; //Update the stack pointer
task_list[pid].active=true;
};
// this gets called by our clock interrupt regularly!
uint32_t task_switch_next(uint32_t oldesp)
{
timer_tick();
if(current_task==-2)return oldesp;
if(current_task!=-1)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)", current_task,pid,task_list[pid].esp);
current_task=pid;
return task_list[pid].esp;
}
}
// if no task found retunr the old esp
return oldesp;
}
volatile int c1,c2;
volatile void test1()
{
c1++;
// syscall_write(1,">",1);
}
volatile void test2()
{
c2++;
// syscall_write(1,"<",1);
}
void task_init()
{
task_create(1,test1);
task_create(2,test2);
current_task=-1;
}
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