int debug_printf(const char *format, ...);
debug_printf writes to the Debug Terminal, under control of the string pointed to by format that specifies how subsequent arguments are converted for output. The format string is a standard C printf format string. The actual formatting is performed on the host by the debugger and therefore debug_printf consumes only a very small amount of code and data space, only the overhead to call the function.
If there are insufficient arguments for the format, the behavior is undefined. If the format is exhausted while arguments remain, the excess arguments are evaluated but are otherwise ignored.
debug_printf returns the number of characters transmitted, or a negative value if an output or encoding error occurred.