This directive expects zero or more expressions, of any section, separated by commas.
The size of the number emitted, and its byte order, depend on what target computer the assembly is for.
Warning: Special Treatment to support Compilers
Machines with a 32-bit address space, but that do less than 32-bit addressing, require the following special treatment. If the machine of interest to you does 32-bit addressing (or doesn’t require it; see Machine Dependent Features), you can ignore this issue.
In order to assemble compiler output into something that works,
as occasionally does strange things to ‘.word’ directives.
Directives of the form ‘.word sym1-sym2’ are often emitted by
compilers as part of jump tables. Therefore, when
as assembles a
directive of the form ‘.word sym1-sym2’, and the difference between
sym2 does not fit in 16 bits,
creates a secondary jump table, immediately before the next label.
This secondary jump table is preceded by a short-jump to the
first byte after the secondary table. This short-jump prevents the flow
of control from accidentally falling into the new table. Inside the
table is a long-jump to
sym2. The original ‘.word’
sym1 minus the address of the long-jump to
If there were several occurrences of ‘.word sym1-sym2’ before the
secondary jump table, all of them are adjusted. If there was a
‘.word sym3-sym4’, that also did not fit in sixteen bits, a
sym4 is included in the secondary jump table,
.word directives are adjusted to contain
minus the address of the long-jump to
sym4; and so on, for as many
entries in the original jump table as necessary.