Update to allow low power mode to be used with the RTOS.

Source/portable/Rowley/MSP430F449/portext.asm

@@ -1,6 +1,56 @@
+/*
+	FreeRTOS.org V5.0.4 - Copyright (C) 2003-2008 Richard Barry.
+
+	This file is part of the FreeRTOS.org distribution.
+
+	FreeRTOS.org is free software; you can redistribute it and/or modify
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+
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+	Please ensure to read the configuration and relevant port sections of the
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+*/
+
 #include "FreeRTOSConfig.h"
 
 portSAVE_CONTEXT macro
+                /* Save the remaining registers. */
 		push	r4
 		push	r5
 		push	r6
@@ -37,6 +87,12 @@ portRESTORE_CONTEXT macro
 		pop		r6
 		pop		r5
 		pop		r4
+
+		/* The last thing on the stack will be the status register.
+                Ensure the power down bits are clear ready for the next
+                time this power down register is popped from the stack. */
+		bic.w   #0xf0,0(SP)
+
 		reti
 		endm
 /*-----------------------------------------------------------*/