as: M68HC11-Modifiers
9.22.3 Symbolic Operand Modifiers
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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 corresponding 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)
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