Index: boot_flash_start.s
===================================================================
--- /YC3121_demo/Librarier/startup/boot_flash_start.s	(revision 735)
+++ /YC3121_demo/Librarier/startup/boot_flash_start.s	(working copy)
@@ -230,26 +230,30 @@
 				
 hard_fault_handler PROC
 			EXPORT  hard_fault_handler         
-			bl 		HARD_FAULT_IRQHandler
-			b 		isr_ret
+			ldr r0,=HARD_FAULT_IRQHandler
+			bx r0
+			nop
 			ENDP
 		
 svc_handler PROC
 			EXPORT  svc_handler         
-			bl 		SVC_IRQHandler
-			b 		isr_ret
+			ldr r0,=SVC_IRQHandler
+			bx r0
+			nop
 			ENDP
 
 pendsv_handler PROC
 			EXPORT  pendsv_handler      
-			bl 		PENDSV_IRQHandler
-			b 		isr_ret
+			ldr r0,=PENDSV_IRQHandler
+			bx r0
+			nop
 			ENDP
 		
 systick 	PROC
 			EXPORT systick 
-			bl    	 SYSTICK_IRQHandler
-			b 		 isr_ret
+			ldr r0,=SYSTICK_IRQHandler
+			bx r0
+			nop
 			ENDP
 
 
@@ -283,13 +287,6 @@
 			bx r0
 			ENDP
 				
-isr_ret		PROC
-			movs r0,#0
-			subs r0,#7
-			mov lr,r0
-			bx lr
-			ENDP
-				
 isr_app     PROC
 			LDR R1,= APPSTARTADDR
 			LDR R1,[R1]
Index: flash_start.s
===================================================================
--- /YC3121_demo/Librarier/startup/flash_start.s	(revision 735)
+++ /YC3121_demo/Librarier/startup/flash_start.s	(working copy)
@@ -9,27 +9,31 @@
 
 
 hard_fault_handler PROC
-			EXPORT  hard_fault_handler         
-			bl HARD_FAULT_IRQHandler
-			b isr_ret
+			EXPORT  hard_fault_handler 
+			ldr r0,=HARD_FAULT_IRQHandler       
+			bx r0
+			nop
 			ENDP
 		
 svc_handler PROC
 			EXPORT  svc_handler         
-			bl SVC_IRQHandler
-			b isr_ret
+			ldr r0,=SVC_IRQHandler
+			bx r0
+			nop
 			ENDP
 
 pendsv_handler PROC
 			EXPORT  pendsv_handler      
-			bl PENDSV_IRQHandler
-			b isr_ret
+			ldr r0,=PENDSV_IRQHandler
+			bx r0
+			nop
 			ENDP
 		
 systick 	PROC
 			EXPORT systick 
-			bl    	 SYSTICK_IRQHandler
-			b 		 isr_ret
+			ldr r0,=SYSTICK_IRQHandler
+			bx r0
+			nop
 			ENDP
 		
 irq0 		PROC
@@ -230,14 +234,6 @@
 			ldr r0,[r0, r1]
 			bx r0
 			ENDP
-				
-isr_ret		PROC
-			movs r0,#0
-			subs r0,#7
-			mov lr,r0
-			bx lr
-			ENDP
-			
 					
 				ALIGN	
 NMI_IRQHandler  		PROC