feat:Cooperative Multitasking

1 files changed, 28 insertions, 0 deletions

diff --git a/src/kernel/timer.cc b/src/kernel/timer.cc
new file mode 100644
index 0000000..8cb3b0f
--- /dev/null
+++ b/src/kernel/timer.cc
@@ -0,0 +1,28 @@
+#include "common/types.h"
+#include "kernel/timer.h"
+
+#define CLINT_BASE 0x2000000L
+#define CLINT_MTIMECMP(hartid) (CLINT_BASE + 0x4000 + 8 * (hartid))
+#define CLINT_MTIME (CLINT_BASE + 0xBFF8)
+
+#define INTERVAL 1000000
+
+namespace Timer{
+    uint64 get_time(){
+        return *(volatile uint64*)CLINT_MTIME;
+    }
+
+    void set_next_trigger(){
+        uint64 mtime = get_time();
+
+        *(volatile uint64 *)CLINT_MTIMECMP(0) = mtime + INTERVAL;
+    }
+
+    void init(){
+        set_next_trigger();
+        uint64 sie;
+        asm volatile("csrr %0, sie" : "=r"(sie));
+        sie |= (1L << 5);
+        asm volatile("csrw sie, %0" : : "r"(sie));
+    }
+}
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