Espresso 0.0.2c

lib/scheduler.c

@@ -0,0 +1,76 @@
+
+#include <stdlib.h>
+#include <string.h>
+
+#include <drivers/irq.h>
+
+#include <scheduler.h>
+
+
+#define STACK_SIZE (8192)
+
+task_t* current_task = NULL;
+task_t* task_list = NULL;
+uint32_t next_pid = 1;
+
+
+void init_scheduler(void)
+{
+  set_irq_handler(0, (irq_func_t) schedule);
+}
+
+void scheduler(registers_t* boot_regs)
+{
+  task_t* task = malloc(sizeof(task_t));
+
+  task->id = next_pid++;
+  task->regs = boot_regs;
+  task->next = task;
+
+  task_list = task;
+  current_task = task;
+}
+
+registers_t* schedule(registers_t* regs)
+{
+  if (!current_task)
+  {
+    return regs;
+  }
+
+  current_task->regs = regs;
+
+  current_task = current_task->next;
+
+  return current_task->regs;
+}
+
+task_t* create_task(void (*entry)())
+{
+  task_t* task = malloc(sizeof(task_t));
+  uint32_t* stack = malloc(STACK_SIZE);
+
+  uint32_t stack_top = (uint32_t)stack + 4096;
+
+  stack_top -= sizeof(registers_t);
+  registers_t* regs = (registers_t*)stack_top;
+
+  memset(regs, 0, sizeof(registers_t));
+
+  regs->eip = (uint32_t) entry;
+  regs->cs  = 0x08; /* kernel code */
+  regs->ds  = 0x10;
+  regs->es  = 0x10;
+  regs->fs  = 0x10;
+  regs->gs  = 0x10;
+  regs->eflags = 0x202; /* IF = 1 */
+
+  task->id = next_pid++;
+  task->regs = regs;
+
+  /* insert into circular list */
+  task->next = task_list->next;
+  task_list->next = task;
+
+  return task;
+}