RxUsbRegisterChangeNotification

Description

Registers semaphores for generic attach/detach notification of USB devices.

Syntax

 rc = RxUsbRegisterChangeNotification(NotifyID,hDevAdd,hDevRem)

Parameters

NotifyID

the name of the variable to receive the Notification Identifier.

hDevAdd

the handle of the event semaphore to be posted on device attach.

hDevRem

the handle of the event semaphore to be posted on device detach.

Return Code

0x0000 - NO_ERROR

Errors

0x0006 - ERROR_INVALID_HANDLE
0x0057 - ERROR_INVALID_PARAMETER
0x005F - ERROR_INTERRUPT
0x0067 - ERROR_TOO_MANY_SEM_REQUESTS
0x0069 - ERROR_SEM_OWNER_DIED
0x1B58 - USB_NOT_INIT
0x1B59 - USB_ERROR_NO_MORE_NOTIFICATTIONS
0xFF06 - ERROR_INVALID_HANDLE
0xFF1F - ERROR_GEN_FAILURE
0xFF57 - ERROR_INVALID_PARAMETER
0xFF64 - ERROR_TOO_MANY_SEMAPHORES

Remarks

Device attach/detach notifications may be obtained by registering event semaphores to be posted upon attach/detach of USB devices. The RexxUtil library provides functions to work with event semaphores. Some of these are used in the example code.

Example Code

/* add SysCreateEventSem */
rc = RxFuncAdd('SysCreateEventSem','RexxUtil','SysCreateEventSem')
say '+SysCreateEventSem(),RC=0x'd2x(rc)

/* invoke SysCreateEventSem() */
hSemAttach = SysCreateEventSem()
say '*SysCreateEventSem(),RC=0x'd2x(rc)
hSemDetach = SysCreateEventSem()
say '*SysCreateEventSem(),RC=0x'd2x(rc)

/* drop SysCreateEventSem */
rc = RxFuncDrop('SysCreateEventSem')
say '-SysCreateEventSem(),RC=0x'd2x(rc)

/* add RxUsbRegisterChangeNotification */
rc = RxFuncAdd('RxUsbRegisterChangeNotification','usbcalls','RxUsbRegisterChangeNotification')
say '+RxUsbRegisterChangeNotification(),RC=0x'd2x(rc)

/* invoke RxUsbRegisterChangeNotification */
hDevAdd = hSemAttach; /* attach semaphore handle */
hDevRem = hSemDetach; /* detach semaphore handle */
drop NotifyID /* to receive the notification identifier */
rc = RxUsbRegisterChangeNotification(NotifyID,hDevAdd,hDevRem)
say '*RxUsbRegisterChangeNotification(),RC=0x'd2x(rc)

/* drop RxUsbRegisterChangeNotification */
rc = RxFuncDrop('RxUsbRegisterChangeNotification')
say '-RxUsbRegisterChangeNotification(),RC=0x'd2x(rc)

/* add SysWaitEventSem */
rc = RxFuncAdd('SysWaitEventSem','RexxUtil','SysWaitEventSem')
say '+SysWaitEventSem(),RC=0x'd2x(rc)

/* invoke SysWaitEventSem() */
timeout = 8000; /* await 8 seconds */
rc = SysWaitEventSem(hSemAttach,timeout)
say '*SysWaitEventSem(),RC=0x'd2x(rc)
if (rc=0) then say 'obtained Attach Notification'
rc = SysWaitEventSem(hSemDetach,timeout)
say '*SysWaitEventSem(),RC=0x'd2x(rc)
if (rc=0) then say 'obtained Detach Notification'

/* drop SysWaitEventSem */
rc = RxFuncDrop('SysWaitEventSem')
say '-SysWaitEventSem(),RC=0x'd2x(rc)