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Assembler Reference
3-24 Copyright © 2000, 2001 ARM Limited. All rights reserved. ARM DUI 0068B
3.6.9 Operator precedence
The assembler includes an extensive set of operators for use in expressions. Many of the
operators resemble their counterparts in high-level languages such as C (see Unary
operators on page 3-26 and Binary operators on page 3-28).
There is a strict order of precedence in their evaluation:
1. Expressions in parentheses are evaluated first.
2. Operators are applied in precedence order.
3. Adjacent unary operators are evaluated from right to left.
4. Binary operators of equal precedence are evaluated from left to right.
Note
The order of precedence is not exactly the same as in C.
For example,
(1 + 2 :SHR; 3)
evaluates as
(1 + (2 :SHR: 3))
= 1 in
armasm
. The
equivalent expression in C evaluates as
((1 + 2) >> 3)
= 0.
You are recommended to use brackets to make the precedence explicit.
Table 3-2 shows the order of precedence of operators in
armasm
, and a comparison with
the order in C.
If your code contains an expression which would parse differently in C,
armasm
normally
gives a warning:
A1466W: Operator precedence means that expression would evaluate differently in C
The warning is not given if you use the
-unsafe
command line option.
Table 3-2 Operator precedence in armasm
armasm precedence equivalent C operators
unary operators unary operators
* / :MOD
:
* / %
string manipulation n/a
:SHL: :SHR: :ROR: :ROL: << >>