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