1 files changed, 76 insertions, 0 deletions
diff --git a/src/kernel/tasks.c b/src/kernel/tasks.c
new file mode 100644
index 0000000..164409a
--- /dev/null
+++ b/src/kernel/tasks.c
@@ -0,0 +1,76 @@
+#include "tasks.h"
+
+#include "kernel.h"
+#include "string.h"
+
+void task_init( task_t *task, uint16_t gdt_code_segment_selector, task_func_t *entrypoint )
+{
+	memset( task, 0, sizeof( task_t ) );
+	
+	task->cpu_state = (cpu_state_t *)( task->stack + TASK_STACK_SIZE - sizeof( cpu_state_t ) );
+	
+	task->cpu_state->eax = 0;
+	task->cpu_state->ebx = 0;
+	task->cpu_state->ecx = 0;
+	task->cpu_state->edx = 0;
+	task->cpu_state->esi = 0;
+	task->cpu_state->edi = 0;
+	task->cpu_state->ebp = 0;
+
+	// neded for security spaces and users
+	//~ task->cpu_state->esp = 0;
+	//~ task->cpu_state->ss = 0;
+
+	task->cpu_state->eip = (uint32_t)entrypoint;
+	task->cpu_state->cs = gdt_code_segment_selector;
+
+	// TODO: why?
+	task->cpu_state->eflags = 0x202;	
+	
+	//~ task->cpu_state->error = 0;
+
+	//~ task->cpu_state->gs = 0;
+	//~ task->cpu_state->fs = 0;
+	//~ task->cpu_state->es = 0;
+	//~ task->cpu_state->ds = 0;
+}
+
+void task_manager_init( task_manager_t *manager )
+{
+	memset( manager, 0, sizeof( task_manager_t ) );
+	
+	manager->nof_tasks = 0;
+	manager->current_task = -1;
+	memset( manager->task, 0, MAX_NOF_TASKS * sizeof( task_t * ) );
+}
+
+void task_manager_add_task( task_manager_t *manager, task_t *task )
+{
+	if( manager->nof_tasks >= MAX_NOF_TASKS - 1 ) {
+		kernel_panic( "Allocating more than %d tasks.. increase kernel constant MAX_NOF_TASKS", MAX_NOF_TASKS );
+	}
+
+	manager->task[manager->nof_tasks] = task;
+	manager->nof_tasks++;
+}
+
+cpu_state_t *task_manager_schedule_task( task_manager_t *manager, cpu_state_t *cpu_state )
+{
+	// no tasks, no task switch
+	if( manager->nof_tasks == 0 ) {
+		return cpu_state;
+	}
+	
+	// store state of the current task
+	if( manager->current_task >= 0 ) {
+		manager->task[manager->current_task]->cpu_state = cpu_state;
+	}
+		
+	// pick next task (simple round robin)
+	manager->current_task++;
+	if( manager->current_task >= manager->nof_tasks ) {
+		manager->current_task = 0;
+	}
+	
+	return manager->task[manager->current_task]->cpu_state;
+}