*** UNIX MANUAL PAGE BROWSER ***

REQUEST(9.2) REQUEST(9.2) NAME request, own, wait, alarm, sleep, nap, kbdchar, rcvchar, realtime, sendchar, sendnchars, kill, exit - 5620 input/output requests SYNOPSIS #include <jerq.h> void request(r) int r; int own(r) int r; int wait(r) int r; void alarm(t) unsigned t; void sleep(t) unsigned t; void nap(t) unsigned t; long realtime(); int kbdchar(); int rcvchar(); void sendchar(c) int c; void sendnchars(n, cp) int n; char *cp; void kill(s) int s; void exit(); DESCRIPTION Request announces a program's intent to use I/O devices and resources, and is usually called once early in a program. The bit vector r indi- cates which resources are to be used by OR'ing together one or more of the elements KBD (keyboard), MOUSE, RCV (characters received by termi- nal from Unix), SEND (characters sent from terminal to Unix) and ALARM. For example, request(MOUSE|KBD) indicates that the process wants to use the mouse and keyboard. If the keyboard is not requested, characters typed will be sent to the standard input of the Unix process. If the mouse is not requested, mouse events in the process's layer will be in- terpreted by the system rather than passed to the process. SEND and CPU (see wait below) are always implicitly requested. Request sleeps for one clock tick to synchronize mouse control with the kernel. Own returns a bit vector of which I/O resources have data available. For example, own()&KBD indicates whether a character is available to be read by kbdchar (see below), own()&MOUSE tells if the process's mouse structure (see button(9.2)) is current, and own()&ALARM indicates whether the alarm timer has fired. Wait's argument r is a bit vector composed as for request. Wait sus- pends the process, enabling others, until at least one of the requested resources is available. The return value is a bit vector indicating which of the requested resources are available -- the same as own()&r. Processes wishing to give up the processor to enable other processes to run may call wait(CPU); it will return as soon as all other active processes have had a chance to run. CPU is a fake resource which is always requested. The SEND pseudo-resource is unused; wait(SEND) al- ways succeeds. Alarm starts a timer which will fire t ticks (60ths of a second) into the future. A pseudo-resource ALARM can be used to check the status of the timer with own or wait. Calling alarm implicitly requests the ALARM pseudo-resource. Nap busy loops for t ticks of the 60Hz internal clock. To avoid beat- ing with the display, programs drawing rapidly changing scenes should nap for two ticks between updates, to synchronize the display and mem- ory. Nap busy loops until the time is up; sleep is identical except that it gives up the processor for the interval. Except when unwilling to give up the mouse, a program should call sleep in preference to nap. Sleep does not interfere with alarm, and vice versa. Realtime returns the number of 60Hz clock ticks since mux started. Kbdchar returns the next keyboard character typed to the process. If no characters have been typed, or KBD has not been requested, kbdchar returns -1. Rcvchar returns the next character received from the host, typically written on the standard output of a Unix process. If there are no characters available, or RCV has not been requested, rcvchar returns -1. Sendchar sends a single byte to the host, which will normally be read on the standard input of the Unix process. Sendnchars sends to the host n characters pointed to by p. Kill sends the associated Unix process the signal s; see signal(2). Exit terminates the process. Unlike on Unix, exit does not return an exit status to a parent. Calling exit replaces the running process by the default terminal program. Any associated Unix process must arrange for its own demise; exit is a purely local function. When a process calls exit, all local resources: keyboard, mouse, storage, etc., are deallocated automatically. Realtime returns the number of sixtieths of a second elapsed since mux(9.1) was started. EXAMPLES request(KBD|RCV); for(;;){ r=wait(KBD|RCV); if(r&KBD) keyboard(kbdchar()); if(r&RCV) receive(rcvchar()); } Take input from either the keyboard or the host. SEE ALSO button(9.2) BUGS own()&MOUSE does not guarantee that you own the mouse. The correct test is (own()&MOUSE) && ptinrect(mouse.xy, Drect) REQUEST(9.2)