1 files changed, 63 insertions, 0 deletions
diff --git a/os/thread.h b/os/thread.h
new file mode 100644
index 0000000..2213d6f
--- /dev/null
+++ b/os/thread.h
@@ -0,0 +1,63 @@
+#ifndef THREAD_H
+#define THREAD_H
+
+#include <stdint.h>
+
+class Thread {
+	friend void switch_context();
+	
+	private:
+		struct int_frame_t {
+			// Software saved.
+			uint32_t r4;
+			uint32_t r5;
+			uint32_t r6;
+			uint32_t r7;
+			uint32_t r8;
+			uint32_t r9;
+			uint32_t r10;
+			uint32_t r11;
+			uint32_t lr_ex;
+			
+			// Hardware saved.
+			uint32_t r0;
+			uint32_t r1;
+			uint32_t r2;
+			uint32_t r3;
+			uint32_t r12;
+			uint32_t lr;
+			uint32_t pc;
+			uint32_t psr;
+		};
+		
+		int_frame_t* sp;
+		
+		Thread* next;
+		
+		static Thread* active_thread;
+		static Thread main_thread;
+		
+		Thread() : next(this) {}
+	
+	public:
+		Thread(void* stack, uint32_t stack_size, void (*func)()) {
+			sp = (int_frame_t*)((uint8_t*)stack + stack_size - sizeof(int_frame_t));
+			
+			sp->lr_ex = 0xfffffff9;
+			
+			// frame->lr = thread exit handler
+			sp->pc = (uint32_t)func;
+			sp->psr = 0x01000000;
+		}
+		
+		void start() {
+			next = active_thread->next;
+			active_thread->next = this;
+		}
+		
+		static inline void yield() {
+			asm volatile("svc 0");
+		}
+};
+
+#endif