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.\" $XConsortium: p259,v 5.3 94/04/17 20:57:26 hersh Exp $
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$XMCOPY
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.ds b \s-2BREAK\s+2
.TH "REQUEST VALUATOR" 3P "29 February 1991"
.SH NAME
REQUEST VALUATOR \- request an operator interaction with a valuator device
.IX "Request Input Mode" "REQUEST VALUATOR"
.IX "Input Modes" "REQUEST VALUATOR"
.IX "Valuator Input Devices" "REQUEST VALUATOR"
.SH SYNOPSIS
.SS C Syntax
.ft B
.ta 1.25i 3i
.nf
void
preq_val ( ws, dev, in_status, value )
Pint	ws;	\fIworkstation identifier\fP
Pint	dev;	\fIvaluator device number\fP
Pin_status	*in_status;	\fI\s-2OUT\s+2 input status\fP
Pfloat	*value;	\fI\s-2OUT\s+2 value\fP
.fi
.ft R
.SS Required PHIGS Operating States
(PHOP, WSOP, *, *)
.SH DESCRIPTION
.SS Purpose
Use \s-2REQUEST VALUATOR\s+2 to request an operator interaction with a
specified valuator device. The device must be in request mode. See
\s-2SET VALUATOR MODE\s+2 and \s-2INITIALIZE VALUATOR\s+2
for more information.
See the \fIAvailable Devices\fP section of
\s-2INITIALIZE VALUATOR\s+2 for a
description of the available valuator devices.
.LP
The request suspends \s-2PHIGS\s+2 until the
specified device is triggered
or the operator performs a \*b.
A \*b is performed by typing the \s-2CONTROL\s+2 and \s-2D\s+2 keys
simultaneously (^D).
.SS C Input Parameters
.IP \fIws\fP
Workstation identifier. An integer specifying the workstation with which
the requested valuator device is associated.
.IP \fIdev\fP
The device number of the requested valuator device.
See the \fIAvailable Devices\fP section of
\s-2INITIALIZE VALUATOR\s+2 for a
description of the available valuator devices.
.SS C Output Parameter
.IP \fIin_status\fP
A pointer to the location to store the request status.
Pin_status is defined in phigs.h as follows:
.sp .4
.ta .5i
.nf
typedef enum {
.sp .2
	PIN_STATUS_NONE,
	PIN_STATUS_OK,
	PIN_STATUS_NO_IN
.sp .2
} Pin_status;
.fi
.sp .4
.IP \fIvalue\fP
A pointer to the location to store the valuator value.
.LP
.SS Execution
\s-2REQUEST VALUATOR\s+2 requests a logical input value from the specified
valuator device. The specified device must be in request mode. See
\s-2SET VALUATOR MODE\s+2 for more information.
.LP
\s-2REQUEST VALUATOR\s+2 creates a measure
process for the specified device and suspends \s-2PHIGS\s+2 until the
device is triggered or the operator issues a \*b. 
A \*b is generated by the operator by depressing the
\s-2CONTROL\s+2 and \s-2D\s+2 keys
simultaneously (^D).
.LP
If a \*b occurs, a status of \s-2PIN_STATUS_NO_IN\s+2
is returned and the valuator data
is undefined.  If a status of \s-2PIN_STATUS_OK\s+2 is returned,
the valuator data is
available.  In either case,
the measure process is then terminated and
\s-2PHIGS\s+2 processing resumes.
.LP
See \s-2INITIALIZE VALUATOR\s+2 for a description of
the available valuator
devices.
.SH ERRORS
.IP 003
Ignoring function, function requires state (\s-2PHOP, WSOP, *, *\s+2)
.IP 054
Ignoring function, the specified workstation is not open
.IP 061
Ignoring function, specified workstation is neither of category \s-2INPUT\s+2
nor of category \s-2OUTIN\s+2
.IP 250
Ignoring function, the specified device is not available
on the specified workstation
.IP 251
Ignoring function, the function requires the input
device to be in \s-2REQUEST\s+2 mode
.SH SEE ALSO
.nf
.IP
.ta 0.5i
.SM "INITIALIZE VALUATOR (3P)"
.SM "SET VALUATOR MODE (3P)"
.fi
