HWI Module
Application Program Interface
2-151
Notes
In the following notes, references to the usage of HWI_enter/HWI_exit
also apply to usage of the HWI dispatcher since, in effect, the dispatcher
calls HWI_enter/HWI_exit.
❏
Do not call SWI_disable or SWI_enable within an HWI function.
❏
Do not call HWI_enter, HWI_exit, or any other DSP/BIOS functions
from a non-maskable interrupt (NMI) service routine. In addition, the
HWI dispatcher cannot be used with the NMI service routine.
❏
Do not call HWI_enter/HWI_exit from a HWI function that is invoked
by the dispatcher.
❏
The DSP/BIOS API calls that require an HWI function to use
HWI_enter and HWI_exit are:
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
Any PIP API call can cause the pipe’s notifyReader or notifyWriter
function to run. If an HWI function calls a PIP function, the notification
functions run as part of the HWI function.
An HWI function must use HWI_enter and HWI_exit or must be
dispatched by the HWI dispatcher if it indirectly runs a function
containing any of the API calls listed above.
If your HWI function and the functions it calls do not call any of these
API operations, you do not need to disable SWI scheduling by calling
HWI_enter and HWI_exit.