Motorola HC12 User Manual

Operating Procedures

Using Direct Addressing Mode to Access Symbols

MCUez HC12 Assembler

User’s Manual

MOTOROLA

Operating Procedures

233

NOTE:

The statement

NAMES test1.o test2.o END

lists the two object files

building the application. A space character separates the object filenames. The
section

CodeSec

is defined in both object files. In

test1.o

, the section

CodeSec

contains the symbol

AddSource

. In

test2.o

, the section

CodeSec

contains the symbol

entry

. According to the order in which the

object files are listed in the

NAMES

block, the function

AddSource

will be

allocated first (at address 0xB00) and symbol

entry

will be allocated next to

it.

11.6 Using Direct Addressing Mode to Access Symbols

The different methods to inform the assembler it should use the direct
addressing mode on a symbol are discussed here.

11.6.1 Using Direct Addressing Mode to Access External Symbols

External symbols that should be accessed using the direct addressing mode,
must be declared by the directive

XREF.B.

Example:

XREF.B ExternalDirLabel

XREF ExternalExtLabel

…

LDD ExternalDirLabel

; Direct addressing mode is used

…

LDD ExternalExtLabel

; Extended addressing mode is used

11.6.2 Using Direct Addressing Mode to Access Exported Symbols

Symbols that are exported using the directive

XDEF.B

, will be accessed by the

direct addressing mode. Symbols that are exported using the directive

XDEF

are accessed using the extended addressing mode.

Example:

XDEF.B DirLabel

XDEF ExtLabel

…

LDD DirLabel ; Direct addressing mode is used

…

LDD ExtLabel ; Extended addressing mode is used