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is a pointer to a variable used to hold an error code:
OS_ERR_FATAL_RETURN
if If we ever return to this function.
OS_ERR_OS_NOT_RUNNING
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INIT
µC/OS-III not initialized.
OS_ERR_OS_NO_APP_TASK
No application task created.
OS_ERR_OS_RUNNING
If the kernel is already running. In other words, if this function has already been called.
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