Specifications

System Macros Invoked by Drivers
$VIELD, _VIELD
$VIELD, _VIELD
Defines symbolic offsets and masks for bit fields.
Format
$VIELD
_VIELD
mod ,inibit ,fields
Parameters
mod
Module in which this bit field is defined; the prefix portion of the name of the
symbol to be defined.
inibit
Bit within the field on which the positions of the bits to be defined are based.
fields
One or more fields of the form <sym,[size=1],[mask]>, where these arguments
are defined as follows:
Argument Meaning
sym String appended to the string ‘‘mod$’’ to form the name of
this bit field.
[size=1] Size in bits of this bit field. If you specify a value greater
than 1, the VIELD macro generates a symbol for the size of
the bit field.
[mask] Character ‘‘M’’ if the VIELD macro is to generate a symbol
for the mask of the bit field, blank otherwise.
Description
The $VIELD and _VIELD macros define bit fields whose names have the
form mod$x_sym and mod_x_sym (where x can be V, S, or M and sym is a
value supplied in the fields argument). Because the dollar-sign character ($)
is reserved for use in system-defined symbols, use of the _VIELD macro is
recommended for non-Digital-supplied device drivers.
See the descriptions of the $DEFINI and $EQULST macros for additional
information on defining symbols for data structure fields.
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