Echelon Neuron - Manual (Page 51)

Stack-Effect Comments
In general, the data stack is documented as a set of ordered values from left to
right, with TOS in the first (left-most) position. For example, if the values 1 and
2 were on the data stack, with 1 in TOS and 2 in NEXT, and the current
instruction is a PUSHS instruction to push the value 0 onto the stack, the stack-
effect comment would be (0,1,2), as shown below:
pushs #0 ; (0, 1, 2)
The comment follows the instruction, so that the stack-effect comment shows the
stack layout after the instruction has been executed. In this case, the comment
shows that 0 has been pushed onto the stack, and the previous values 1 and 2
have been moved to the right (down the stack).
Note that this stack-effect comment does not show the entire stack, that is, the
data stack contains more than the three values 0, 1, and 2. Instead, the comment
shows only enough stack elements to clarify how the stack is changed by the
current instruction or function call. You could add an ellipsis (...) or a double
hyphen (--) to the right of the changed values to remind you that there is more
data on the stack (for example, (0,1,2,…)). However, the ellipsis or double
dash is not necessary.
In general, you do not know the actual data values on the stack, but instead you
are pushing and popping variables. Add the variable name (or a portion of it) to
the stack comment, for example:
push interface_type ; (type)
Stack values are unsigned one-byte scalars unless stated otherwise.
Multi-Byte Values
For multi-byte values, add the element’s size, in bytes, to the value in the
comment. Enclose the size in parentheses following the value itself. For
example, for a 16-bit value named address, the comment would read as
address(2). Therefore, the following two stack-effect comments are equivalent:
; (address(2), …)
; (addresslo, addresshi, …)
Pointer Values
For pointer values, use square brackets ([ ]) to indicate that the value is fetched
from an address. For example, the following stack-effect comment describes one
byte from the location address(2):
; ([address(2)])
Conditional Values
Occasionally, stack elements are conditional. For example, the BRNEQ
instruction drops TOS if the comparison (which is part of the BRNEQ operation)
results in equality, but leaves TOS intact otherwise. Use braces ({ }) to indicate
conditional stack elements. For example, the following comment indicates that
Neuron Assembly Language Reference 41