The assemblers in Gforth generally use a postfix syntax, i.e., the instruction name follows the operands.
The operands are passed in the usual order (the same that is used in the manual of the architecture). Since they all are Forth words, they have to be separated by spaces; you can also use Forth words to compute the operands.
The instruction names usually end with a
,. This makes it easier
to visually separate instructions if you put several of them on one
line; it also avoids shadowing other Forth words (e.g.,
Registers are usually specified by number; e.g., (decimal)
specifies registers R11 and F11 on the Alpha architecture (which one,
depends on the instruction). The usual names are also available, e.g.,
s2 for R11 on Alpha.
Control flow is specified similar to normal Forth code (see Arbitrary control structures), with
conditions are specified in a way specific to each assembler.
Note that the register assignments of the Gforth engine can change
between Gforth versions, or even between different compilations of the
same Gforth version (e.g., if you use a different GCC version). So if
you want to refer to Gforth's registers (e.g., the stack pointer or
TOS), I recommend defining your own words for refering to these
registers, and using them later on; then you can easily adapt to a
changed register assignment. The stability of the register assignment
is usually better if you build Gforth with
The most common use of these registers is to dispatch to the next word
next routine). A portable way to do this is to jump to
' noop >code-address (of course, this is less efficient than
next code and scheduling it well).
Another difference between Gforth version is that the top of stack is
kept in memory in
gforth and, on most platforms, in a register in