1 files changed, 123 insertions, 0 deletions
diff --git a/src/stem/task.c b/src/stem/task.c
new file mode 100644
index 0000000..874f22d
--- /dev/null
+++ b/src/stem/task.c
@@ -0,0 +1,123 @@
+#include "task.h"
+#include "sys.h"
+#include "mem.h"
+#include "timer.h"
+#include "monitor.h"
+
+#define KSTACKSIZE 0x8000
+
+//From task_.asm
+extern uint32_t read_eip();
+extern void task_idle(void*);
+
+static uint32_t thread_runnable(struct thread *th);
+
+uint32_t nextpid = 1;
+
+struct process *processes = 0;
+struct thread *threads = 0, *current_thread = 0;
+
+void tasking_init(thread_entry whereToGo, void *data) {
+	cli();
+	struct process *pr = kmalloc(sizeof(struct process));	//This process must be hidden to users
+	pr->pid = pr->uid = 0;
+	pr->parent = pr;
+	pr->pagedir = kernel_pagedir;
+	pr->next = 0;
+	current_thread = 0;
+	thread_new(pr, task_idle, 0);
+	thread_new(pr, whereToGo, data);
+	sti();
+	monitor_write("Tasking starting\n");
+	tasking_switch();
+}
+
+static struct thread *thread_next() {		//NOT OPTIMAL : will allocate time slices to idle thread even if busy
+	if (current_thread == 0) current_thread = threads;
+	struct thread *ret = current_thread;
+	while (1) {
+		ret = ret->next;
+		if (ret == 0) ret = threads;
+		if (thread_runnable(ret)) {
+		   return ret;
+		}
+	}
+}
+
+void tasking_switch() {
+	if (threads == 0) return;	//no tasking yet
+	cli();
+
+	uint32_t esp, ebp, eip;
+
+	asm volatile("mov %%esp, %0" : "=r"(esp));
+	asm volatile("mov %%ebp, %0" : "=r"(ebp));
+	eip = read_eip();
+
+	if (eip == 0x12345) {
+		return;
+	}
+
+	if (current_thread != 0) {
+		current_thread->esp = esp;
+		current_thread->ebp = ebp;
+		current_thread->eip = eip;
+	}
+
+	current_thread = thread_next();
+
+	asm volatile("			\
+			mov %0, %%ebp;	\
+			mov %1, %%esp;	\
+			mov %2, %%ecx;	\
+			mov $0x12345, %%eax;	\
+			jmp *%%ecx;"
+		: : "r"(current_thread->ebp), "r"(current_thread->esp), "r"(current_thread->eip));
+}
+
+uint32_t tasking_handleException(struct registers *regs) {
+	if (threads == 0) return 0;	//No tasking yet
+	return 0;
+}
+
+static uint32_t thread_runnable(struct thread *t) {
+	if (t->state == TS_RUNNING) return 1;
+	if (t->state == TS_SLEEPING && timer_time() >= t->timeWait) return 1;
+	return 0;
+}
+
+static void thread_run(struct thread *thread, thread_entry entry_point, void *data) {
+	pagedir_switch(thread->process->pagedir);
+	asm volatile("sti");
+	entry_point(data);
+	asm volatile("int $64");
+}
+
+void thread_new(struct process *proc, thread_entry entry_point, void *data) {
+	struct thread *t = kmalloc(sizeof(struct thread));
+	t->process = proc;
+	t->kernelStack_addr = kmalloc(KSTACKSIZE);
+	t->kernelStack_size = KSTACKSIZE;
+
+	uint32_t *stack = (uint32_t*)((size_t)t->kernelStack_addr + t->kernelStack_size);
+
+	//Pass parameters
+	stack--; *stack = (uint32_t)data;
+	stack--; *stack = (uint32_t)entry_point;	
+	stack--; *stack = (uint32_t)t;
+	stack--; *stack = 0;
+	t->esp = (uint32_t)stack;
+	t->ebp = t->esp + 8;
+	t->eip = (uint32_t)thread_run;
+
+	t->state = TS_RUNNING;
+
+	if (threads == 0) {
+		threads = t;
+	} else {
+		struct thread *i = threads;
+		while (i->next != 0) i = i->next;
+		i->next = t;
+	}
+}
+