III.4 Expressions

Arithmetic expressions are composed of operands, operators and parentheses. Operands may be user-defined symbols, constants or special assembler symbols. All operands are treated as unsigned 16-bit numbers. Special assembler symbols, that can be used as operands are:

AR0, ... , AR7	direct addresses of registers R0 thru R7
$	the location counter of the currently active segment (start address of the current assembler statement)

The following operators are implemented:

Unary Operators

Operator	Operation	Definition
+	identity	+x = x
-	two's complement	-x = 0-x
NOT	one's complement	NOT x = FFFFH-x
HIGH	high order byte
LOW	low order byte

Binary Operators

Operator	Operation	Result
+	unsigned addition
-	unsigned subtraction
*	unsigned multiplication
/	unsigned division
MOD	unsigned remainder
SHL	logical shift left
SHR	logical shift right
AND	logical and
OR	logical or
XOR	exclusive or
.	bit operator used for bit-adressable locations
EQ   or   =	equal to	0 if FALSE, FFFFH if TRUE
NE   or   <>	not equal to
LT   or   <	less than
LE   or   <=	less or equal than
GT   or   >	greater than
GE   or   >=	greater or equal than

Operators that are no special characters but keywords as SHR or AND must be separated from their operands by at least one blank or tab. In general expressions are evaluated from left to right according to operator precedence, which may be overridden by parentheses. Parentheses may be nested to any level.
Expressions always evaluate to unsigned 16-bit numbers, while overflows are ignored. When an expression result is to be assigned to an 8-bit quantity, the high byte must be either 00 or FF.

Operator Precedence

Operator(s)	Type	Precedence
(   )		highest
+   -   NOT   HIGH   LOW	unary
.
*   /   MOD
SHL   SHR
+   -	binary
EQ   =   NE   <>   LT   <   LE   <=   GT   >   GE   >=
AND
OR   XOR		lowest

Example:

The expression

        P1.((87+3)/10 AND -1 SHR 0DH)

will evaluate to 91H.