Espresso 0.0.2c

files/pit.c

@@ -0,0 +1,62 @@
+#include <types.h>
+#include <port_io.h>
+#include <stdio.h>
+
+#include <scheduler.h>
+
+#include <drivers/pit.h>
+
+
+#define PIT_CHANNEL0       0x40
+#define PIT_COMMAND        0x43
+#define PIT_IRQ_LINE       0
+#define PIT_FREQUENCY_BASE 1193182
+
+volatile uint64_t pit_ticks = 0;
+bool pit_initialized = false;
+
+void pit_init(void)
+{ 
+#ifdef _DEBUG
+  printf("[ PIT ] Initializing the PIT...\n");
+#endif
+
+  uint16_t divisor = (uint16_t) 1193;
+
+  /* Send command byte */
+  outb(PIT_COMMAND, 0x36);  /* Channel 0, low/high byte, mode 3 (square wave), binary */
+
+  /* Send divisor low and high byte */
+  outb(PIT_CHANNEL0, (uint8_t)(divisor & 0xFF));        /* Low byte */
+  outb(PIT_CHANNEL0, (uint8_t)((divisor >> 8) & 0xFF)); /* High byte */
+  
+  pit_initialized = true;
+  
+#ifdef _DEBUG
+  printf("[ PIT ] PIT Initialized\n");
+#endif
+}
+
+void pit_handler(void)
+{
+  pit_ticks++;
+}
+
+/*void pit_sleep(uint64_t ms)
+{
+  uint64_t target = pit_ticks + ms;
+  while (pit_ticks < target)
+  {
+    asm volatile ("hlt");
+  }
+}*/
+
+void pit_sleep(uint64_t ms)
+{
+  extern task_t* current_task;
+  
+  current_task->wakeup_tick = pit_ticks + ms;
+  current_task->state = TASK_SLEEPING;
+
+  asm volatile("int $32"); /* force reschedule immediately */
+}