6 dcd and dcdu – ARM VERSION 1.2 User Manual

Page 301

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Directives Reference

ARM DUI 0068B

Copyright © 2000, 2001 ARM Limited. All rights reserved.

7-19

7.3.6

DCD and DCDU

The

DCD

directive allocates one or more words of memory, aligned on 4-byte boundaries,

and defines the initial runtime contents of the memory.

&

is a synonym for

DCD

.

DCDU

is the same, except that the memory alignment is arbitrary.

Syntax

{label} DCD{U} expr{,expr}

where:

expr

is either:

a numeric expression (see Numeric expressions on page 3-20).

a program-relative expression.

Usage

DCD

inserts up to 3 bytes of padding before the first defined word, if necessary, to achieve

4-byte alignment.

Use

DCDU

if you do not require alignment.

See also:

DCB on page 7-18

DCW and DCWU on page 7-25

DCQ and DCQU on page 7-24

SPACE on page 7-17.

Examples

data1 DCD 1,5,20 ; Defines 3 words containing
; decimal values 1, 5, and 20

data2 DCD mem06 + 4 ; Defines 1 word containing 4 +
; the address of the label mem06

AREA MyData, DATA, READWRITE
DCB 255 ; Now misaligned ...
data3 DCDU 1,5,20 ; Defines 3 words containing
; 1, 5 and 20, not word aligned

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