Assembler control directives

In this section:

Syntax

/*comment*/

//comment

CASEOFF

CASEON

ERROR "message"

RADIX expr

Parameters

`comment`	Comment ignored by the assembler.
`expr`	Default base—default 10 (decimal).
`message`	Text to be displayed.

Description

These directives provide control over the operation of the assembler. For information about the restrictions that apply when using a directive in an expression, see Expression restrictions.

Directive	Description	Expression restrictions
`/comment/`	C-style comment delimiter.
`//`	C++ style comment delimiter.
`CASEOFF`	Disables case sensitivity.
`CASEON`	Enables case sensitivity.
`ERROR`	Generates an error.
`RADIX`	Sets the default base on all numeric values.	No forward references No external references Absolute Fixed

Table 131. Assembler control directives

Use /*...*/ to comment sections of the assembler listing.

Use // to mark the rest of the line as comment.

Use RADIX to set the default base for constants. The default base is 10.

Controlling case sensitivity

Use CASEON or CASEOFF to turn case sensitivity on or off for user-defined symbols. By default, case sensitivity is on.

When CASEOFF is active all symbols are stored in upper case, and all symbols used by the linker should be written in upper case in the linker definition file.

When CASEOFF is set, label and LABEL are identical in this example:

            module  caseSensitivity1
            section .text:CODE(2)

            caseoff
label       nop                 ; Store as "LABEL".
            br      LABEL
            end

The following will generate a duplicate label error:

            module  caseSensitivity2
            section .text:CODE(2)
            caseoff
label       nop                 ; Store as "LABEL".
LABEL       nop                 ; Error, "LABEL" already defined.
            end

Generating errors

Use ERROR to force the assembler to generate an error. It us useful in, for example, macros:

MyMacro     macro
            if \0 == 7
            error "Wrong first parameter"
            endif
            endm

Defining comments

This example shows how /*...*/ can be used for a multi-line comment:

/*
Program to read serial input.
Version 1: 19.2.25
Author: mjp
*/

Changing the base

To set the default base to 16:

            module  radix
            section .text:CODE(2)

            radix   16            ; With the default base set
            mov     12,r6         ; to 16, the immediate value
            ;...                  ; of the load instruction is
                                  ; interpreted as 0x12.

; To reset the base from 16 to 10 again, the argument must be
; written in hexadecimal format.

            radix   0xa           ; Reset the default base to 10.
            mov     12,r6         ; Now, the immediate value of
            ;...                  ; the load instruction is
                                  ; interpreted as 0x0c.
            end

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