Fix #1204, Use mask instead of cast to alter value

Jacob Hageman · Jacob Hageman · commit 8913ce522bc1 · 2021-03-16T16:54:35.000-04:00
diff --git a/modules/msg/fsw/src/cfe_msg_msgid_v1.c b/modules/msg/fsw/src/cfe_msg_msgid_v1.c
@@ -65,8 +65,9 @@ int32 CFE_MSG_SetMsgId(CFE_MSG_Message_t *MsgPtr, CFE_SB_MsgId_t MsgId)
         return CFE_MSG_BAD_ARGUMENT;
     }
 
-    MsgPtr->CCSDS.Pri.StreamId[0] = (uint8)(msgidval >> 8);
-    MsgPtr->CCSDS.Pri.StreamId[1] = (uint8)(msgidval);
+    /* Shift and mask bytes to be endian agnostic */
+    MsgPtr->CCSDS.Pri.StreamId[0] = (msgidval >> 8) & 0xFF;
+    MsgPtr->CCSDS.Pri.StreamId[1] = msgidval & 0xFF;
 
     return CFE_SUCCESS;
 }

Original file line number	Diff line number	Diff line change
`@@ -65,8 +65,9 @@ int32 CFE_MSG_SetMsgId(CFE_MSG_Message_t *MsgPtr, CFE_SB_MsgId_t MsgId)`
`65`	`65`	`return CFE_MSG_BAD_ARGUMENT;`
`66`	`66`	`}`
`67`	`67`
`68`		`- MsgPtr->CCSDS.Pri.StreamId[0] = (uint8)(msgidval >> 8);`
`69`		`- MsgPtr->CCSDS.Pri.StreamId[1] = (uint8)(msgidval);`
	`68`	`+ /* Shift and mask bytes to be endian agnostic */`
	`69`	`+ MsgPtr->CCSDS.Pri.StreamId[0] = (msgidval >> 8) & 0xFF;`
	`70`	`+ MsgPtr->CCSDS.Pri.StreamId[1] = msgidval & 0xFF;`
`70`	`71`
`71`	`72`	`return CFE_SUCCESS;`
`72`	`73`	`}`