The operands to instructions and directives are comprised of expressions. Expressions can be made up of numbers, identifiers, strings and operators.
Operators can be unary (one operand, e.g., not) or binary
(two operands, e.g., +). The operators allowable in expressions are listed
in the Table 1 table.
The usual rules governing the syntax of expressions apply.
The operators listed can all be freely combined in both constant and relocatable expressions. The linker permits relocation of complex expressions, so the results of expressions involving relocatable identifiers cannot be resolved until link time.
| Operator | Purpose | Example |
|---|---|---|
* |
multiplication | movlw 4*33,w |
+ |
addition | bra $+1 |
- |
subtraction | DB 5-2 |
/ |
division | movlw 100/4 |
= or
eq |
equality | IF inp eq 66 |
> or
|
signed greater than | IF inp > 40 |
>= or
ge |
signed greater than or equal to | IF inp ge 66 |
< or
lt |
signed less than | IF inp < 40 |
<= or
le |
signed less than or equal to | IF inp le 66 |
<> or
ne |
signed not equal to | IF inp <> 40 |
low |
low byte of operand | movlw low(inp) |
high |
high byte of operand | movlw high(1008h) |
highword |
high 16 bits of operand | DW highword(inp) |
mod |
modulus | movlw 77mod4 |
& or
and |
bitwise AND | clrf inp&0ffh |
^ |
bitwise XOR (exclusive or) | movf inp^80,w |
| |
bitwise OR | movf inp|1,w |
not |
bitwise complement | movlw not 055h,w |
<< or
shl |
shift left | DB inp>>8 |
>> or
shr |
shift right | movlw inp shr 2,w |
rol |
rotate left | DB inp rol 1 |
ror |
rotate right | DB inp ror 1 |
float24 |
24-bit version of real operand | DW float24(3.3) |
nul |
tests if macro argument is null |