Enabling or Disabling the Idle State
You can reset the activity timer to 15 seconds, disable and enable the idle
state, and read the current CPU clock speed by using Power Manager routines.
Keep in mind that it is almost always better to design your code so that it is
not affected by the idle state; then the Macintosh Portable can conserve power
whenever possible. Note also that disabling the idle state does not disable the
sleep state. To prevent your program from being adversely affected by the
sleep state, place a routine in the sleep queue, as described in
To reset the activity timer to count down another 15 seconds before the
Power Manager puts the Macintosh Portable in the idle state, use the returns the value in the Ticks global variable at the time the function was called.
If you want to disable the idle state-that is, prevent the Macintosh Por table
from entering the idle state-for more than 15 seconds, use the DisableIdle procedure. If your application cannot tolerate the idle state at all, you can call
the DisableIdle procedure when your application starts up and then call the EnableIdle procedure when your application terminates. procedure. Note that canceling the last call to the DisableIdle procedure is not the same thing as enabling the idle state. For example, if the user has used
the Portable control panel to disable the idle state, then a call to the
EnableIdle procedure does not enable the idle state. Similarly, if your routine called the DisableIdle procedure more than once or if another routine
has called the DisableIdle procedure, then a call to the EnableIdle procedure cancels only the last call to the DisableIdle procedure; it does not enable the idle state.
call to the DisableIdle procedure has been matched by a call to the EnableIdle procedure, and then only if the user has not disabled the idle state through the Portable control panel. For this reason, you must be very
careful to match each call to the DisableIdle procedure with a single call to the EnableIdle procedure. Be careful to avoid making extra calls to the EnableIdle procedure so that you do not inadvertently reenable the idle state while another routine needs it to remain disabled.
Calls to the EnableIdle procedure are not cumulative; that is, after you make several calls to the EnableIdle procedure, a single call to the DisableIdle procedure still disables the idle state. Disabling the idle state always takes precedence over enabling the idle state. A call to the DisableIdle procedure disables the idle state no matter how many times the EnableIdle
procedure has been called and whether or not the user has enabled the idle state
through the Portable control panel.
The following examples might help to clarify these concepts:
• If the application calls the EnableIdle routine but the user disables or has disabled the idle state, the idle state is disabled.
• If the application calls the DisableIdle routine and the user enables or has enabled the idle state, the idle state is disabled.
• If the application calls the DisableIdle routine twice in a row and then calls the EnableIdle routine once, the idle state is disabled. • If the application calls the EnableIdle routine twice in a row and then calls the DisableIdle routine once, the idle state is disabled. • If the idle state is initially enabled and if the application calls the
routine twice, the Power Manager first disables and then re enables the idle state.
To determine whether the Macintosh Portable is currently in the idle state,
read the current clock speed with the GetCPUSpeed function. The only values returned by the GetCPUSpeed function are 1 and 16, indicating the effective clock speed in megahertz.