The redirection of character I/O is carried out within the
Boot Monitor platform library routines in
During startup, the platform library executes a Software
Interrupt instruction (SWI). If the image is being executed
without a debugger (or the debugger is not capturing semihosting
calls) the value returned by this SWI is -1, otherwise the value
returned is positive. The platform library uses the return value to
determine the hardware device used for outputting from the C library
I/O functions (Redirection is through a SWI to the debugger console
or directly to a hardware device).
Supported devices for character output are:
:UART-0(default destination if debugger is not capturing semihosting calls)
The STDIO calls are redirected within
Redirection depends on the setting of User Switches 2 and 3, see Boot Monitor configuration switches for details.