as: 2byte
7.109 '.2byte EXPRESSION [, EXPRESSION]*'
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This directive expects zero or more expressions, separated by commas.
If there are no expressions then the directive does nothing. Otherwise
each expression is evaluated in turn and placed in the next two bytes of
the current output section, using the endian model of the target. If an
expression will not fit in two bytes, a warning message is displayed and
the least significant two bytes of the expression's value are used. If
an expression cannot be evaluated at assembly time then relocations will
be generated in order to compute the value at link time.
This directive does not apply any alignment before or after inserting
the values. As a result of this, if relocations are generated, they may
be different from those used for inserting values with a guaranteed
alignment.
This directive is only available for ELF targets,