Zilog ZUSBOPTS - Manual (Page 251)

UM017105-0511 Expressions
Zilog Developer Studio II – ZNEO™
User Manual
223
indicated by the absence of a sign. Negative numbers are indicated by a minus sign ( - )
preceding the number. Underscores (_) can be inserted between octal digits to improve
readability. For example:
1234o ; octal number
-1234o ; negative octal number
1_234o; octal number with underscore
Character Constants
A single printable ASCII character enclosed by single quotes ( ' ) can be used to represent
an ASCII value. This value can be used as an operand value. For example:
'A' ; ASCII code for "A"

'3' ; ASCII code for "3"
Operator Precedence
Table 20 shows the operator precedence in descending order, with operators of equal pre-
cedence on the same line. Operators of equal precedence are evaluated left to right. Paren-
theses can be used to alter the order of evaluation.
Shift Left (<<) and OR (|) have the same operator precedence and are evaluated from left
to right. If you must alter the order of evaluation, add parentheses to ensure the appropriate
operator precedence. For example:
ld r0, # 1<<2 | 1<<2 | 1<<1
The constant expression in the preceding instruction evaluates to 2A H.
If you want to perform the Shift Left operations before the OR operation, use parentheses
as follows:
ld r0, #(1<<2)|(1<<2)|(1<<1)
The modified constant expression evaluates to 6 H.
Table 20. Operator Precedence
Level 1 ()
Level 2 ~ unary- ! low
Level 3 ** * / %
Level 4 + - & | ^ >> <<
Level 5 < > <= >= == !=