NAME

initiate_request −  start a request process without waiting the result. 

SYNOPSIS

C SYNTAX

void initiate_request(fildes,class,ordinal,valid);
int fildes,class,ordinal,*valid;

FORTRAN77 SYNTAX

        subroutine initiate_request(fildes,class,ordinal,valid)
        integer*4 fildes,class,ordinal,valid

PASCAL SYNTAX

procedure initiate_request(fildes,class,ordinal:integer;
var valid:integer);

HP-UX COMPATIBILITY

Level: HP-UX/STANDARD

Origin: ANSI Computer Graphics Interface

DESCRIPTION

INPUT PARAMETERS

fildes
is an integer file descriptor returned by gopen when an I/O path to a graphics device is opened. 
class
is one of the following device classes: LOCATOR or CHOICE.
ordinal
is a logical device number ranging from 1 to the number of devices of this class.

OUTPUT PARAMETER

valid
If the device is not initialized, or requests are not supported on a specific device, valid is set to FALSE (0);  otherwise it is set to TRUE (1).  When Pascal is used, 0 and 1 are used since TRUE and FALSE are reserved words in that programming language. 

DESCRIPTION

If the device is supported, initiate_request posts a request against it.  The request is completed when the device is triggered (in a device dependent manner), or when the request is canceled by receipt of a corresponding request_choice or request_locator that times out. 
 
A request may be performed on an input device while it is enabled for event generation.  The events enabled mode is saved by the device and restored after the request has been executed.
 
The request data does not go into the event queue, but into a separate virtual register.  Its availability can be determined by inquire_request_status, and it is read by request_choice or request_locator. 
 
A request can be done without first initiating it.
 
This element is provided to better utilize those devices which support asynchronous sampling during a pending request.  This allows a program to continue other operations while a request has been started.

SEE ALSO

inquire_request_status(3g), request_choice(3g), request_locator(3g). 

Hewlett-Packard Company  —  May 11, 2021