9.21.2.1 Symbolic Operand Modifiers

The assembler supports several modifiers when using symbol addresses in M32C instruction operands. The general syntax is the following:

     %modifier(symbol)
%dsp8
%dsp16
These modifiers override the assembler's assumptions about how big a symbol's address is. Normally, when it sees an operand like ‘ sym[a0] ’ it assumes ‘ sym ’ may require the widest displacement field (16 bits for ‘ -m16c ’, 24 bits for ‘ -m32c ’). These modifiers tell it to assume the address will fit in an 8 or 16 bit (respectively) unsigned displacement. Note that, of course, if it doesn't actually fit you will get linker errors. Example:
          mov.w %dsp8(sym)[a0],r1
          mov.b #0,%dsp8(sym)[a0]

%hi8
This modifier allows you to load bits 16 through 23 of a 24 bit address into an 8 bit register. This is useful with, for example, the M16C ‘ smovf ’ instruction, which expects a 20 bit address in ‘ r1h ’ and ‘ a0 ’. Example:
          mov.b #%hi8(sym),r1h
          mov.w #%lo16(sym),a0
          smovf.b

%lo16
Likewise, this modifier allows you to load bits 0 through 15 of a 24 bit address into a 16 bit register.
%hi16
This modifier allows you to load bits 16 through 31 of a 32 bit address into a 16 bit register. While the M32C family only has 24 bits of address space, it does support addresses in pairs of 16 bit registers (like ‘ a1a0 ’ for the ‘ lde ’ instruction). This modifier is for loading the upper half in such cases. Example:
          mov.w #%hi16(sym),a1
          mov.w #%lo16(sym),a0
          ...
          lde.w [a1a0],r1