278
Section 3: Assembler
TI
-
89 / TI
-
92 Plus Sierra C Assembler Reference Manual
Not for Distribution
Beta Version February 2, 2001
3.8.2. Structured Control Macros
The structured control macro facility provided by
asm68k
is a set of high-level
language constructs, which are used to generate run-time loops and conditional
execution. These macros expand into the appropriate assembly code to perform
the desired control structure. Since these macros are implemented efficiently,
they improve readability without sacrificing the desirable aspects of using
assembly language. The remainder of this section describes their usage.
Note:
Structured control macros do
not
provide assembly-time control — they provide run-time
control.
3.8.2.1. Structured Control Expressions
Structured control expressions are used to specify the flow of execution for
certain structured control macros. These expressions are translated into one or
more
CMP
,
BRA
, and
Bcc
instructions to provide the necessary flow of control.
The expressions themselves have a logical value of true of false. They are used
with the
IF
,
UNTIL
, and
WHILE
directives. The syntax for constructing structured
control expressions is as follows:
Syntax
I. <
cc1
> [
logical_op
[.
size
] <
cc2
>]
II. <
cc1
> [
logical_op
[.
size
]
op3
<
cc2
>
op4
]
III.
op1
<
cc1
>
op2
[
logical_op
[.
size
] <
cc2
>]
IV.
op1
<
cc1
>
op2
[
logical_op
[.
size
]
op3
<
cc2
>
op4
]
Description
cc1
cc2
Specifies one of the integer conditional tests shown in Table 3.30.
Floating-point and PMMU conditional tests are not supported. The angle
brackets that enclose the conditional test are required characters.
op1
op2
op3
op4
Specifies an effective address expression (see section
3.5 Effective
Addressing Modes
).
logical_op
Specifies one of the following logical operators:
AND
Logical AND
OR
Logical OR
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