M32C-Modifiers - Using as
Description: Using as

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##### 9.19.2.1 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