prom_stdin_ihandle
rv = prom_read(prom_stdin_ihandle(), &c, 1, 0, BYTE);
istdin = prom_stdin_ihandle();
if ((istdin = prom_stdin_ihandle()) == (ihandle_t)-1)
extern ihandle_t prom_stdin_ihandle(void);
istdin = prom_stdin_ihandle();