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9.19.2 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