Service Request Structure

SVC_request           db           ?

Set by handler to indicate that a request is pending. A non-zero value indicates that the handler requires servicing. A greater value means a higher priority. The priority only has meaning if there are multple service request pending.

SVC_app_index         db           ?

TCB entry # associated to linked application. This value is used by system manager to invoke the compliant app. The application can get its assigned TCB entry by making a m_current_task() call. The application is notified through an event type of E_REQUEST. Typically the application will be running as a background task. An application can determine it's current run mode by issuing a m_get_run_mode() call.

SVC_user_ptr          dd           ?

General purpose usage. Usually points to a buffer to be processed by the application (input). This address is passed on to the linked app via an E_REQUEST, through a special structure entry (Event.e_svc_user_ptr).

SVC_user_type         dd           ?

General purpose usage. May be used to pass a command to an application. This address is passed on to the linked app via an E_REQUEST, through a special structure entry (Event.e_svc_user_type).

SVC_user_id           db           4 dup(?)

Identifiying signature set by service handler. First 3 chars should describe service. Last char could indicate version. User locates desired service through m_locate_SVC( char *service_type[4]). A "?" indicates a wild card character. A successful match returns a far pointer to the corresponding service entry.

SVC_user_entry        dd           ?

Set by handler during initialization. Points to a user (app) call entry point. This entry point must handle at least the above six call types (link, unlink, hook, unhook, request complete, unload). The app will pass a far pointer accessable at BP+6. The first byte is the command.

SVC_safe_entry        dd           ?

Set by handler during initialization. Points to a DOS or system manager safe call entry point. Enables special handlers to make DOS and system manager calls at "safe" times. Handler sets up service request flags as for app scheduling, except the SVC_appp_index is set to 0ffh.

SVC_used              db           ?

Set and cleared by system manager indicates that entry is used.

SVC_status            db           ?

Set by system manager. Under certain conditions a request may fail. The failure code is stored here.