C166/ST10 Cross-Assembler, Linker/Locator, Utilities ... - Tasking

7−20
DIRECTIVES
DW CSEC1 ; Store the segment number
; of CSEC1 section
Chapter 7
− Initializing with a string (DB only)
With the DB directive you can define a string up to 200
characters long. Each character is stored in a byte, where
successive characters occupy successive bytes. The string
must be enclosed within single or double quotes. If you want
to include a single or double quote in a string, code it as two
consecutive quotes, or use a single quote in a string enclosed
within double quotes or vice versa.
ALPHABET DB ’ABCDEFGHIJKLMNOPQRSTUVWXYZ’
DIGITS DB ″0123456789″
SINGLEQUOTE DB ″This isn’t hard″
DOUBLEQUOTE DB ’This isn’’t hard also’
number Is a constant expression which determines the number of
bytes that must be reserved. No initialization is done.
Examples:
− Constant expression − a numeric value
TEN DB 6+4 ; Initialize a byte: 0AH
DW 10 ; Initialize a word: 000AH
CONSTA DW ″?B″ ; Initialize a word: 3F42H
; ^^ constant string of maximum 2 bytes,
; evaluated to a number.
LONG1 DDW 012345678h ; initialize a double word
− Indeterminate initialization
RESERVE DS 2 ; Reserve two bytes. This word
; is not aligned.
RESBYTES DSB 4 ; Reserve four bytes.
RESWORDS DSW 2 ; Reserve four bytes.
RESDWRD DSDW 1 ; reserve four bytes
− An address expression − the offset or base part of a variable or label
SEGBASE DW DSEC ; Store page number of DATA section
COFFSET DW POF VAR ; Store offset value of VAR
LBASE DW SEG LAB1 ; Store segment number of LAB1
DBASE DW PAG VAR ; Store page number of VAR
ADDR DDW VAR ; store full 32 bit address of VAR