implement timer

src/timer.rs

@@ -0,0 +1,18 @@
+const TIMER_CLO: u32 = 0x3F00_3004;
+
+fn read_clo() -> u32 {
+    unsafe { return core::ptr::read_volatile(TIMER_CLO as *const u32) }
+}
+
+pub unsafe fn sleep(microseconds: u32) {
+    let start = read_clo();
+    while read_clo() - start < microseconds {
+        core::arch::asm!("nop");
+    }
+}
+
+pub unsafe fn delay_nops(count: u32) {
+    for _ in 0..count {
+        core::arch::asm!("nop");
+    }
+}