Echelon Neuron - Manual (Page 23)

Table 5. Special Operator Functions
Function Description
LB Extracts the low byte of the expression
HB Extracts the high byte of the expression
(logical shift right by eight bits)
NEAR Offset value for the RAMNEAR area
(only computable at link time)
Example:
The following example demonstrates the use of the @NEAR expression. The
example implements a one-byte variable in the RAMNEAR segment, and a
function named Example that increments this global variable.
; open RAMNEAR segment, declare one byte
; uninitialized variable
SEG RAMNEAR
ORG
myVariable EXPORT
RES 1
; The Example routine takes no arguments and produces
; no results, but increments the global variable
SEG CODE
ORG
pNear EQU 1
Example APEXP ; ( -- )
push [pNear][@NEAR(myVariable)]
inc
pop [pNear][@NEAR(myVariable)]
ret ; return to caller
Constant Expressions
A constant expression is a general expression that is computable at assembly time
and has a constant value in an appropriate range for the specified instruction or
directive.
An expression that is not constant is one that is computable only at link time or
that has a variable value at runtime. Such symbols must be designated as
imported symbols.
Important: An expression that uses either the * or @NEAR special operator
cannot be a constant expression.
When using negative constants, or expressions that yield negative results, in a
byte context, you must use the @LB special operator (or specify the --autotrunc
[-a] command-line switch) to obtain a one-byte value for the value. For example,
use PUSH #@LB(-1) instead of PUSH #-1 (the latter will fail assembly).
Neuron Assembly Language Reference 13