provide an early exception vector table to catch exceptions during startup, before the final table has been set up (in exceptions.S)

BaS_gcc/sources/fault_vectors.c

@@ -0,0 +1,49 @@
+#include "MCF5475.h"
+#include "bas_types.h"
+#include "bas_printf.h"
+
+/*
+ * provide an early exception vector branch table to catch exceptions _before_ VBR has been setup eventually
+ * (to RAMBAR0, in exceptions.S)
+ */
+
+typedef void (*exception_handler)(void);
+extern exception_handler SDRAM_VECTOR_TABLE[];
+
+void fault_handler(uint32_t format_status, uint32_t pc)
+{
+	xprintf("\007\007exception!\r\n");
+	xprintf("format_status: %lx\r\n", format_status);
+	xprintf("pc: %lx\r\n", pc);
+	xprintf("processor halted.\r\n");
+}
+
+void handler(void)
+{
+	/*
+	 * for standard routines, we'd have to save registers here.
+	 * Since we do not intend to return anyway, we just ignore that
+	 */
+	__asm__ __volatile__("move.l	(sp),-(sp)\n\t"		/* format, fault status and status register values */
+						 "move.l	8(sp),-(sp)\n\t"	/* the program counter where the fault originated */
+						 "bra		_fault_handler\n\t"
+						 "halt\n\t"
+							: : :);
+}
+
+void setup_vectors(void)
+{
+	int i;
+
+	for (i = 0; i < 256; i++)
+	{
+		SDRAM_VECTOR_TABLE[i] = handler;
+	}
+
+	/*
+	 * make sure VBR points to our table
+	 */
+	__asm__ __volatile__("clr.l		d0\n\t"
+						 "movec		d0,VBR\n\t"
+						 "move.l	d0,_rt_vbr");
+}