initial versioin

code/os/06-interrupts/trap.c

@@ -0,0 +1,77 @@
+#include "os.h"
+
+extern void trap_vector(void);
+extern void uart_isr(void);
+
+void trap_init()
+{
+	/*
+	 * set the trap-vector base-address for machine-mode
+	 */
+	w_mtvec((reg_t)trap_vector);
+}
+
+void external_interrupt_handler()
+{
+	int irq = plic_claim();
+
+	if (irq == UART0_IRQ){
+      		uart_isr();
+	} else if (irq) {
+		printf("unexpected interrupt irq = %d\n", irq);
+	}
+	
+	if (irq) {
+		plic_complete(irq);
+	}
+}
+
+reg_t trap_handler(reg_t epc, reg_t cause)
+{
+	reg_t return_pc = epc;
+	reg_t cause_code = cause & 0xfff;
+	
+	if (cause & 0x80000000) {
+		/* Asynchronous trap - interrupt */
+		switch (cause_code) {
+		case 3:
+			uart_puts("software interruption!\n");
+			break;
+		case 7:
+			uart_puts("timer interruption!\n");
+			break;
+		case 11:
+			uart_puts("external interruption!\n");
+			external_interrupt_handler();
+			break;
+		default:
+			uart_puts("unknown async exception!\n");
+			break;
+		}
+	} else {
+		/* Synchronous trap - exception */
+		printf("Sync exceptions!, code = %d\n", cause_code);
+		panic("OOPS! What can I do!");
+		//return_pc += 4;
+	}
+
+	return return_pc;
+}
+
+void trap_test()
+{
+	/*
+	 * Synchronous exception code = 7
+	 * Store/AMO access fault
+	 */
+	*(int *)0x00000000 = 100;
+
+	/*
+	 * Synchronous exception code = 5
+	 * Load access fault
+	 */
+	//int a = *(int *)0x00000000;
+
+	uart_puts("Yeah! I'm return back from trap!\n");
+}
+