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