Using as: M32C-Modifiers

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#### 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

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