update source to match draft

src/interrupts.rs

@@ -0,0 +1,10 @@
+use pic8259_simple::ChainedPics;
+use spin;
+
+pub const PIC_1_OFFSET: u8 = 32;
+pub const PIC_2_OFFSET: u8 = PIC_1_OFFSET + 8;
+
+pub static PICS: spin::Mutex<ChainedPics> =
+    spin::Mutex::new(unsafe { ChainedPics::new(PIC_1_OFFSET, PIC_2_OFFSET) });
+
+pub const TIMER_INTERRUPT_ID: u8 = PIC_1_OFFSET;