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ir - infrared remote control module


include     "ir.m";

ir    := load Ir Ir->PATH; # for real remotes
simir := load Ir Ir->SIMPATH; # for keyboard simulator

init:       fn(irc: chan of int, pidc: chan of int): int;
translate:  fn(key: int): int;


Programs running with the Prefab toolkit (see prefab-intro(2)) are controlled by an infrared remote control device. If such a device is not present, the system may simulate it from the keyboard by loading the module in file Ir->SIMPATH. Although originally designed for use with Prefab, these modules are general enough to be used directly by non-Prefab applications.

The Ir module defines codes for representing the remote control keys. Whether the remote is real or simulated, the init function does the appropriate actions to initialize the device, and then spawns a process to return the codes on the irc channel. The process ID of that process is sent on the channel pidc when the process starts; init's caller must receive it. It can be used to kill the controlling process when the application finishes.

The codes are:

Ir->ChanUP, Ir->ChanDN
The Channel-Up and Channel-Down buttons. The keyboard equivalents are r and c.
The Enter button. The keyboard equivalent is the SPACE bar.
An end of file from the remote device. After sending one, no more codes will be sent on irc.
An unknown or invalid input from the remote device.
Ir->FF, Ir->Rew
The Fast-Forward and Rewind buttons. The keyboard equivalents are k and j.
The Mute button. There is no keyboard equivalent.
The Power button. The keyboard equivalent is the Delete key.
The Recall button. The keyboard equivalent is x.
The Record button. There is no keyboard equivalent.
The Select button. The keyboard equivalent is the Return or Enter key.
Ir->Up, Ir->Dn
The Up and Down buttons. The keyboard equivalents are i and m.
Ir->VolUP, Ir->VolDN
The Volume-Up and Volume-Down buttons. The keyboard equivalents are t and v.
Ir->Zero, Ir->One, Ir->Two, etc. The digit buttons, 0 through 9. The keyboard equivalents are the corresponding numeral keys.

The translate function converts the device's raw codes into the constants defined by the module. For example, with the simulated remote control, translate('3') returns Ir->Three. Translate is only necessary for programs that wish to manage their own simulation of the remote.

Programs that drive the remote control directly, must load the appropriate Ir implementation module and initialise it. The following example uses the absence of a simulator module to infer that a real remote control is available.

implement Irtest;

include "sys.m";
include "draw.m";
include "ir.m";

Irtest: module
   init:  fn(ctxt: ref Draw->Context, argv: list of string);

init(nil: ref Draw->Context, nil: list of string)
    sys := load Sys Sys->PATH;

    # First try the keyboard Ir simulator.
    # If that is not present, use Ir directly.

    ir := load Ir Ir->SIMPATH;
    if(ir == nil)
        ir = load Ir Ir->PATH;
    if(ir == nil){
        sys->print("Ir module not loaded: %r\n");
    irc := chan of int;
    pidc := chan of int;
    if(ir->init(irc, pidc) < 0){
        sys->print("Can't initialize Ir device: %r\n");
    pid := <-pidc;
    while((irraw := <-irc) != Ir->EOF) {
        irval := ir->translate(irraw);
        if(irval == Ir->Power)
        sys->print("command %d -> %d\n", irraw, irval);

Mux(1) provides one model for the use of an infrared remote control to control a group of applications. Init is invoked once by mux, and the codes then multiplexed between its applications as follows. Mux creates a graphics context for each application (see draw-context(2)). This context includes channels to the mux program and to the Ir device: Draw->Context.ctomux and Draw->Context.cinput. Applications do not see the Ir->Rcl command. Instead, mux program intercepts it and reactivates its own menu. The following example establishes communication with mux and then reads Ir commands until it see Ir->Enter.

implement Command;

include "sys.m";
include "draw.m";
include "ir.m";

Command: module
  init: fn(ref Draw->Context; list of string);

init(ctxt: ref Draw->Context; argv: list of string)
  sys := load Sys Sys->PATH;

  # Tell mux to start sending input.
  ctxt.ctomux <-= Draw->AMstartinput;
  for(;;) {
    key := <-ctxt.cinput;
    sys->print("command %d\n", key);
    if(key == Ir->Enter)

  #  Tell mux this thread is going away.
  ctxt.ctomux <-= Draw->AMexit;




limbo(1), mux(1), intro(2), draw-intro(2), prefab-intro(2)

IR(2 ) Rev:  Thu Feb 15 14:43:27 GMT 2007