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Chapter 27. M68HC11 and M68HC12 Dependent Features

27.3. Symbolic Operand Modifiers

The assembler supports several modifiers when using symbol addresses in 68HC11 and 68HC12

instruction operands. The general syntax is the following:

%modifier(symbol)

%addr

This modifier indicates to the assembler and linker to use the 16 bit physical address correspond 

ing to the symbol. This is intended to be used on memory window systems to map a symbol in

the memory bank window. If the symbol is in a memory expansion part, the physical address

corresponds to the symbol address within the memory bank window. If the symbol is not in a

memory expansion part, this is the symbol address (using or not using the %addr modifier has no

effect in that case).

%page

This modifier indicates to use the memory page number corresponding to the symbol. If the

symbol is in a memory expansion part, its page number is computed by the linker as a number

used to map the page containing the symbol in the memory bank window. If the symbol is not in

a memory expansion part, the page number is 0.

%hi

This modifier indicates to use the 8 bit high part of the physical address of the symbol.

%lo

This modifier indicates to use the 8 bit low part of the physical address of the symbol.

For example a 68HC12 call to a function

foo_example

stored in memory expansion part could be

written as follows:

call %addr(foo_example),%page(foo_example)

and this is equivalent to

call foo_example

And for 68HC11 it could be written as follows:

ldab #%page(foo_example)

stab _page_switch

jsr

%addr(foo_example)

27.4. Assembler Directives

The 68HC11 and 68HC12 version of

as

have the following specific assembler directives: