make set_ipl() a true function (was inlined before)

sys/interrupts.c

@@ -486,3 +486,26 @@ bool gpt0_interrupt_handler(void *arg0, void *arg1)
     return true;
 }
 #endif /* MACHINE_FIREBEE */
+
+
+uint32_t set_ipl(uint32_t ipl)
+{
+    uint32_t ret;
+
+    __asm__ __volatile__(
+        "		move.w	sr,%[ret]\r\n"			/* retrieve status register */
+        "		andi.l	#0x07,%[ipl]\n\t"		/* mask out ipl bits on new value */
+        "		lsl.l	#8,%[ipl]\n\t"			/* shift them to position */
+        "		move.l	%[ret],d0\n\t"			/* retrieve original value */
+        "		andi.l	#0x0000f8ff,d0\n\t"		/* clear ipl part */
+        "		or.l	%[ipl],d0\n\t"			/* or in new value */
+        "		move.w	d0,sr\n\t"				/* put it in place */
+        "		andi.l	#0x0700,%[ret]\r\n"		/* mask out ipl bits */
+        "		lsr.l	#8,%[ret]\r\n"			/* shift them to position */
+        : [ret] "=&d" (ret)		/* output */
+        : [ipl] "d" (ipl)		/* input */
+        : "cc"	/* clobber */
+    );
+
+    return ret;
+}