#*************************************************************************
# Copyright (c) 2002 The University of Chicago, as Operator of Argonne
#     National Laboratory.
# Copyright (c) 2002 The Regents of the University of California, as
#     Operator of Los Alamos National Laboratory.
# EPICS BASE is distributed subject to a Software License Agreement found
# in file LICENSE that is included with this distribution.
#*************************************************************************

=title Multi-Bit Binary Input Record (mbbi)

The normal use for the multi-bit binary input record is to read contiguous,
multiple bit inputs from hardware. The binary value represents a state from a
range of up to 16 states. The multi-bit input record interfaces with devices
that use more than one bit.

Most device support modules obtain values from hardware and place the value in
RVAL. For these device support modules record processing uses RVAL to determine
the current state (VAL is given a value between 0 and 15). Device support
modules may optionally read a value directly into VAL.

Soft device modules are provided to obtain input via database or channel access
links or via dbPutField or dbPutLink requests. Two soft device support modules
are provided: C<<< Soft Channel >>> allows VAL to be an arbitrary unsigned short
integer. C<<< Raw Soft Channel >>> reads the value into RVAL just like normal
device support modules.

=recordtype mbbi

=cut

recordtype(mbbi) {

=head2 Parameter Fields

The record-specific fields are described below, grouped by functionality.

=head3 Scan Parameters

The multi-bit binary input record has the standard fields for specifying under
what circumstances it will be processed.
These fields are listed in L<Scan Fields|dbCommonRecord/Scan Fields>.

=head3 Read and Convert Parameters

The device support routines obtain the record's input from the device or link
specified in the INP field. For records that obtain their input from devices,
the INP field must contain the address of the I/O card, and the DTYP field must
specify the proper device support module. Be aware that the address format
differs according to the I/O bus used.

Two soft device support modules can be specified in DTYP C<Soft Channel> and
C<<< Raw Soft Channel >>>.

C<<< Raw Soft Channel >>> reads the value into RVAL,
upon which the normal conversion process is undergone. C<<< Soft Channel >>>
reads any unsigned integer directly into VAL. For a soft mbbi record, the INP
field can be a constant, a database, or a channel access link. If INP is a
constant, then the VAL is initialized to the constant value but can be changed
at run-time via dbPutField or dbPutLink.

MASK is used by the raw soft channel read routine, and by typical device support
read routines, to select only the desired bits when reading the hardware
register.  It is initialized to ((1 E<lt>E<lt> NOBT) - 1) by record
initialization.  The user can configure the NOBT field, but the device support
routines may set it, in which case the value given to it by the user is simply
overridden.   The device support routines may also override MASK or shift it
left by SHFT bits.   If MASK is non-zero, only the bits specified by MASK will
appear in RVAL.

Unless the device support routine specifies no conversion, RVAL is used to
determine VAL as follows:

=over

=item 1.

RVAL is assigned to a temporary variable -- rval = RVAL

=item 2.

rval is shifted right SHFT number of bits.

=item 3.

A match is sought between rval and one of the state value fields, ZRVL-FFVL.

=back

Each of the fields, ZRVL-FFVL, represents one of the possible sixteen states
(not all sixteen have to be used).

Alternatively, the input value can be read as a string, in which case, a match
is sought with one of the strings specified in the ZRST-FFST fields. Then RVAL
is set equal to the corresponding value for that string, and the conversion
process occurs.

=fields VAL, INP, MASK, NOBT, RVAL, SHFT, ZRVL, ONVL, TWVL, THVL, FRVL, FVVL, SXVL, SVVL, EIVL, NIVL, TEVL, ELVL, TVVL, TTVL, FTVL, FFVL

=head3 Operator Display Parameters

These parameters are used to present meaningful data to the operator. They
display the value and other parameters of the mbbi record either textually or
graphically. The ZRST-FFST fields contain strings describing one of the possible
states of the record. The C<<< get_enum_str >>> and C<<< get_enum_strs >>>
record routines retrieve these strings for the operator. C<<< Get_enum_str >>>
gets the string corresponding to the value set in VAL, and C<<< get_enum_strs
>>> retrieves all the strings.

See L<Fields Common to All Record Types|dbCommonRecord/Operator Display
Parameters> for more on the record name (NAME) and description (DESC) fields.


=fields NAME, DESC, ZRST, ONST, TWST, THST, FRST, FVST, SXST, SVST, EIST, NIST, TEST, ELST, TVST, TTST, FTST, FFST

=cut

	include "dbCommon.dbd"
    %/* Declare Device Support Entry Table */
    %struct mbbiRecord;
    %typedef struct mbbidset {
    %    dset common; /* init_record returns: (-1,0) => (failure, success)*/
    %    long (*read_mbbi)(struct mbbiRecord *prec); /* (0, 2) => (success, success no convert)*/
    %} mbbidset;
    %#define HAS_mbbidset
    %
	field(VAL,DBF_ENUM) {
		prompt("Current Value")
		promptgroup("40 - Input")
		asl(ASL0)
		pp(TRUE)
	}
	field(NOBT,DBF_USHORT) {
		prompt("Number of Bits")
		promptgroup("40 - Input")
		special(SPC_NOMOD)
		interest(1)
	}
	field(INP,DBF_INLINK) {
		prompt("Input Specification")
		promptgroup("40 - Input")
		interest(1)
	}
	field(ZRVL,DBF_ULONG) {
		prompt("Zero Value")
		promptgroup("41 - Input 0-7")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(ONVL,DBF_ULONG) {
		prompt("One Value")
		promptgroup("41 - Input 0-7")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(TWVL,DBF_ULONG) {
		prompt("Two Value")
		promptgroup("41 - Input 0-7")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(THVL,DBF_ULONG) {
		prompt("Three Value")
		promptgroup("41 - Input 0-7")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(FRVL,DBF_ULONG) {
		prompt("Four Value")
		promptgroup("41 - Input 0-7")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(FVVL,DBF_ULONG) {
		prompt("Five Value")
		promptgroup("41 - Input 0-7")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(SXVL,DBF_ULONG) {
		prompt("Six Value")
		promptgroup("41 - Input 0-7")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(SVVL,DBF_ULONG) {
		prompt("Seven Value")
		promptgroup("41 - Input 0-7")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(EIVL,DBF_ULONG) {
		prompt("Eight Value")
		promptgroup("42 - Input 8-15")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(NIVL,DBF_ULONG) {
		prompt("Nine Value")
		promptgroup("42 - Input 8-15")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(TEVL,DBF_ULONG) {
		prompt("Ten Value")
		promptgroup("42 - Input 8-15")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(ELVL,DBF_ULONG) {
		prompt("Eleven Value")
		promptgroup("42 - Input 8-15")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(TVVL,DBF_ULONG) {
		prompt("Twelve Value")
		promptgroup("42 - Input 8-15")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(TTVL,DBF_ULONG) {
		prompt("Thirteen Value")
		promptgroup("42 - Input 8-15")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(FTVL,DBF_ULONG) {
		prompt("Fourteen Value")
		promptgroup("42 - Input 8-15")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(FFVL,DBF_ULONG) {
		prompt("Fifteen Value")
		promptgroup("42 - Input 8-15")
		special(SPC_MOD)
		pp(TRUE)
		base(HEX)
		interest(1)
	}
	field(ZRST,DBF_STRING) {
		prompt("Zero String")
		promptgroup("81 - Display 0-7")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(ONST,DBF_STRING) {
		prompt("One String")
		promptgroup("81 - Display 0-7")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(TWST,DBF_STRING) {
		prompt("Two String")
		promptgroup("81 - Display 0-7")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(THST,DBF_STRING) {
		prompt("Three String")
		promptgroup("81 - Display 0-7")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(FRST,DBF_STRING) {
		prompt("Four String")
		promptgroup("81 - Display 0-7")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(FVST,DBF_STRING) {
		prompt("Five String")
		promptgroup("81 - Display 0-7")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(SXST,DBF_STRING) {
		prompt("Six String")
		promptgroup("81 - Display 0-7")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(SVST,DBF_STRING) {
		prompt("Seven String")
		promptgroup("81 - Display 0-7")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(EIST,DBF_STRING) {
		prompt("Eight String")
		promptgroup("82 - Display 8-15")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(NIST,DBF_STRING) {
		prompt("Nine String")
		promptgroup("82 - Display 8-15")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(TEST,DBF_STRING) {
		prompt("Ten String")
		promptgroup("82 - Display 8-15")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(ELST,DBF_STRING) {
		prompt("Eleven String")
		promptgroup("82 - Display 8-15")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(TVST,DBF_STRING) {
		prompt("Twelve String")
		promptgroup("82 - Display 8-15")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(TTST,DBF_STRING) {
		prompt("Thirteen String")
		promptgroup("82 - Display 8-15")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(FTST,DBF_STRING) {
		prompt("Fourteen String")
		promptgroup("82 - Display 8-15")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}
	field(FFST,DBF_STRING) {
		prompt("Fifteen String")
		promptgroup("82 - Display 8-15")
		special(SPC_MOD)
		pp(TRUE)
		interest(1)
		size(26)
	}

=head3 Alarm Parameters

The possible alarm conditions for multi-bit binary inputs are the SCAN, READ,
and state alarms. The state alarms are configured in the below severity fields.
These fields have the usual possible values for severity fields: NO_ALARM,
MINOR, and MAJOR.

The AFTC field sets the time constant on a low-pass filter that delays the
reporting of limit alarms until the signal has been within the alarm range for
that number of seconds (the default AFTC value of zero retains the previous
behavior).

The unknown state severity (UNSV) field, if set to MINOR or MAJOR, triggers an
alarm when the record support routine cannot find a matching value in the state
value fields for C<<< rval >>>.

The change of state severity (COSV) field triggers an alarm when any change of
state occurs, if set to MAJOR or MINOR.

The other fields, when set to MAJOR or MINOR, trigger an alarm when VAL equals
the corresponding state.

See L<Alarm Specification|https://docs.epics-controls.org/en/latest/guides/EPICS_Process_Database_Concepts.html#alarm-specification>
for a complete explanation of record alarms and of the standard fields.
L<Alarm Fields|dbCommonRecord/Alarm Fields> lists other fields related
to alarms that are common to all record types.

=fields UNSV, COSV, ZRSV, ONSV, TWSV, THSV, FRSV, FVSV, SXSV, SVSV, EISV, NISV, TESV, ELSV, TVSV, TTSV, FTSV, FFSV, AFTC

=cut

	field(ZRSV,DBF_MENU) {
		prompt("State Zero Severity")
		promptgroup("71 - Alarm 0-7")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(ONSV,DBF_MENU) {
		prompt("State One Severity")
		promptgroup("71 - Alarm 0-7")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(TWSV,DBF_MENU) {
		prompt("State Two Severity")
		promptgroup("71 - Alarm 0-7")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(THSV,DBF_MENU) {
		prompt("State Three Severity")
		promptgroup("71 - Alarm 0-7")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(FRSV,DBF_MENU) {
		prompt("State Four Severity")
		promptgroup("71 - Alarm 0-7")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(FVSV,DBF_MENU) {
		prompt("State Five Severity")
		promptgroup("71 - Alarm 0-7")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(SXSV,DBF_MENU) {
		prompt("State Six Severity")
		promptgroup("71 - Alarm 0-7")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(SVSV,DBF_MENU) {
		prompt("State Seven Severity")
		promptgroup("71 - Alarm 0-7")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(EISV,DBF_MENU) {
		prompt("State Eight Severity")
		promptgroup("72 - Alarm 8-15")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(NISV,DBF_MENU) {
		prompt("State Nine Severity")
		promptgroup("72 - Alarm 8-15")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(TESV,DBF_MENU) {
		prompt("State Ten Severity")
		promptgroup("72 - Alarm 8-15")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(ELSV,DBF_MENU) {
		prompt("State Eleven Severity")
		promptgroup("72 - Alarm 8-15")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(TVSV,DBF_MENU) {
		prompt("State Twelve Severity")
		promptgroup("72 - Alarm 8-15")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(TTSV,DBF_MENU) {
		prompt("State Thirteen Sevr")
		promptgroup("72 - Alarm 8-15")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(FTSV,DBF_MENU) {
		prompt("State Fourteen Sevr")
		promptgroup("72 - Alarm 8-15")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(FFSV,DBF_MENU) {
		prompt("State Fifteen Severity")
		promptgroup("72 - Alarm 8-15")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(AFTC, DBF_DOUBLE) {
		prompt("Alarm Filter Time Constant")
		promptgroup("70 - Alarm")
		interest(1)
	}
	field(AFVL, DBF_DOUBLE) {
		prompt("Alarm Filter Value")
		special(SPC_NOMOD)
		interest(3)
	}
	field(UNSV,DBF_MENU) {
		prompt("Unknown State Severity")
		promptgroup("70 - Alarm")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}
	field(COSV,DBF_MENU) {
		prompt("Change of State Svr")
		promptgroup("70 - Alarm")
		pp(TRUE)
		interest(1)
		menu(menuAlarmSevr)
	}

=head3 Run-time Parameters

These parameters are used by the run-time code for processing the multi-bit
binary input.

ORAW is used by record processing to hold the prior RVAL for use in determining
when to post a monitor event for the RVAL field.

The LALM field implements the change of state alarm severity by holding the
value of VAL when the previous change of state alarm was issued.

MLST holds the value when the last monitor for value change was triggered.

SDEF is used by record support to save time if no states are defined.

=fields ORAW, LALM, MLST, SDEF

=cut

	field(RVAL,DBF_ULONG) {
		prompt("Raw Value")
		pp(TRUE)
	}
	field(ORAW,DBF_ULONG) {
		prompt("Prev Raw Value")
		special(SPC_NOMOD)
		interest(3)
	}
	field(MASK,DBF_ULONG) {
		prompt("Hardware Mask")
		special(SPC_NOMOD)
		interest(1)
	}
	field(MLST,DBF_USHORT) {
		prompt("Last Value Monitored")
		special(SPC_NOMOD)
		interest(3)
	}
	field(LALM,DBF_USHORT) {
		prompt("Last Value Alarmed")
		special(SPC_NOMOD)
		interest(3)
	}
	field(SDEF,DBF_SHORT) {
		prompt("States Defined")
		special(SPC_NOMOD)
		interest(3)
	}
	field(SHFT,DBF_USHORT) {
		prompt("Shift")
		promptgroup("40 - Input")
		interest(1)
	}

=head3 Simulation Mode Parameters

The following fields are used to operate the record in simulation mode.

If SIMM (fetched through SIML) is YES or RAW, the record is put in SIMS
severity and the value is fetched through SIOL (buffered in SVAL).
If SIMM is YES, SVAL is written to VAL without conversion,
if SIMM is RAW, SVAL is trancated to RVAL and converted.
SSCN sets a different SCAN mechanism to use in simulation mode.
SDLY sets a delay (in sec) that is used for asynchronous simulation
processing.

See L<Input Simulation Fields|dbCommonInput/Input Simulation Fields>
for more information on simulation mode and its fields.

=fields SIML, SIMM, SIOL, SVAL, SIMS, SDLY, SSCN

=cut

        field(SIOL,DBF_INLINK) {
		prompt("Simulation Input Link")
		promptgroup("90 - Simulate")
		interest(1)
	}
	field(SVAL,DBF_ULONG) {
		prompt("Simulation Value")
	}
	field(SIML,DBF_INLINK) {
		prompt("Simulation Mode Link")
		promptgroup("90 - Simulate")
		interest(1)
	}
	field(SIMM,DBF_MENU) {
		prompt("Simulation Mode")
		special(SPC_MOD)
		interest(1)
		menu(menuSimm)
	}
	field(SIMS,DBF_MENU) {
		prompt("Simulation Mode Severity")
		promptgroup("90 - Simulate")
		interest(2)
		menu(menuAlarmSevr)
	}
    field(OLDSIMM,DBF_MENU) {
        prompt("Prev. Simulation Mode")
        special(SPC_NOMOD)
        interest(4)
        menu(menuSimm)
    }
    field(SSCN,DBF_MENU) {
        prompt("Sim. Mode Scan")
        promptgroup("90 - Simulate")
        interest(1)
        menu(menuScan)
        initial("65535")
    }
    field(SDLY,DBF_DOUBLE) {
        prompt("Sim. Mode Async Delay")
        promptgroup("90 - Simulate")
        interest(2)
        initial("-1.0")
    }
    %#include "callback.h"
    field(SIMPVT,DBF_NOACCESS) {
        prompt("Sim. Mode Private")
        special(SPC_NOMOD)
        interest(4)
        extra("epicsCallback            *simpvt")
    }

=head2 Record Support

=head3 Record Support Routines

=head4 init_record

This routine initializes SIMM with the value of SIML if SIML type is CONSTANT
link or creates a channel access link if SIML type is PV_LINK. SVAL is likewise
initialized if SIOL is CONSTANT or PV_LINK.

This routine next checks to see that device support is available and a device
support read routine is defined. If either does not exist, an error message is
issued and processing is terminated.

Clears MASK and then sets the NOBT low order bits.

If device support includes C<init_record()>, it is called.

init_common is then called to determine if any states are defined. If states are
defined, SDEF is set to TRUE.

=head4 process

See next section.

=head4 special

Calls init_common to compute SDEF when any of the fields ZRVL, ... FFVL change
value.

=head4 get_enum_str

Retrieves ASCII string corresponding to VAL.

=head4 get_enum_strs

Retrieves ASCII strings for ZRST,...FFST.

=head4 put_enum_str

Checks if string matches ZRST,...FFST and if it does, sets VAL.

=head3 Record Processing

Routine process implements the following algorithm:

=over

=item 1.

Check to see that the appropriate device support module exists. If it doesn't,
an error message is issued and processing is terminated with the PACT field
still set to TRUE. This ensures that processes will no longer be called for this
record. Thus error storms will not occur.

=item 2.

readValue is called. See L<Input Records> for more information.

=item 3.

If PACT has been changed to TRUE, the device support read routine has started
but has not completed reading a new input value. In this case, the processing
routine merely returns, leaving PACT TRUE.

=item 4.

Convert:

=over

=item * status=read_mbbi

=item * PACT = TRUE

=item * C<recGblGetTimeStamp()> is called.

=item * If status is 0, then determine VAL

=over

=item * Set rval = RVAL

=item * Shift rval right SHFT bits

=back

=item * If at least one state value is defined

=over

=item * Set UDF to TRUE

=back

=item * If RVAL is ZRVL,...,FFVL then set

=over

=item * VAL equals index of state

=item * UDF set to FALSE

=back

=item * Else set VAL = undefined

=over

=item * Else set VAL = RVAL

=back

=item * Set UDF to FALSE

=over

=item * If status is 1, return 0

=item * If status is 2, set status = 0

=back

=back

=item 5.

Check alarms. This routine checks to see if the new VAL causes the alarm status
and severity to change. If so, NSEV, NSTA and LALM are set.

=item 6.

Check to see if monitors should be invoked.

=over

=item * Alarm monitors are invoked if the alarm status or severity has changed.

=item * Archive and value change monitors are invoked if MLST is not equal to VAL.

=item * Monitors for RVAL are checked whenever other monitors are invoked.

=item * NSEV and NSTA are reset to 0.

=back

=item 7.

Scan forward link if necessary, set PACT FALSE, and return.

=back

=head2 Device Support

=head3 Fields Of Interest To Device Support

Each input record must have an associated set of device support routines.

The primary responsibility of the device support routines is to obtain a new raw
input value whenever read_mbbi is called. The device support routines are
primarily interested in the following fields:

=fields PACT, DPVT, UDF, NSEV, NSTA, NOBT, VAL, INP, RVAL, MASK, SHFT

=head3 Device Support Routines

Device support consists of the following routines:

=head4 long report(int level)

This optional routine is called by the IOC command C<dbior> and is passed the
report level that was requested by the user.
It should print a report on the state of the device support to stdout.
The C<level> parameter may be used to output increasingly more detailed
information at higher levels, or to select different types of information with
different levels.
Level zero should print no more than a small summary.

=head4 long init(int after)

This optional routine is called twice at IOC initialization time.
The first call happens before any of the C<init_record()> calls are made, with
the integer parameter C<after> set to 0.
The second call happens after all of the C<init_record()> calls have been made,
with C<after> set to 1.

=head4 init_record

  init_record(precord)

This routine is optional. If provided, it is called by the record support
C<init_record()> routine. If it uses MASK, it should shift it as necessary and
also give SHFT a value.

=head4 get_ioint_info

  get_ioint_info(int cmd,struct dbCommon *precord,IOSCANPVT *ppvt)

This routine is called by the ioEventScan system each time the record is added
or deleted from an I/O event scan list. C<cmd> has the value (0,1) if the record is
being (added to, deleted from) an I/O event list. It must be provided for any
device type that can use the I/O Event scanner.

=head4 read_mbbi

  read_mbbi(precord)

This routine must provide a new input value. It returns the following values:

=over

=item *

0: Success. A new raw value is placed in RVAL. The record support module
determines VAL from RVAL, SHFT, and ZEVL ... FFVL.

=item *

2: Success, but don't modify VAL.

=item *

Other: Error.

=back

=head3 Device Support For Soft Records

Two soft device support modules C<<< Soft Channel >>> and C<<< Raw Soft Channel
>>> are provided for multi-bit binary input records not related to actual
hardware devices. The INP link type must be either CONSTANT, DB_LINK, or
CA_LINK.

=head4 Soft Channel

read_mbbi always returns a value of 2, which means that no conversion is
performed.

If the INP link type is constant, then the constant value is stored into VAL by
C<init_record()>, and UDF is set to FALSE. VAL can be changed via dbPut
requests. If the INP link type is PV_LINK, then dbCaAddInlink is called by
C<init_record()>.

read_mbbi calls recGblGetLinkValue to read the current value of VAL. See L<Soft
Input>.

If the return status of recGblGetLinkValue is zero, then read_mbbi sets UDF to
FALSE. The status of recGblGetLinkValue is returned.

=head4 Raw Soft Channel

This module is like the previous except that values are read into RVAL, VAL is
computed from RVAL, and read_mbbi returns a value of 0. Thus the record
processing routine will determine VAL in the normal way.

=cut

}
