AVR-Modifiers - Using as
Description: Using as

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##### 9.4.2.3 Relocatable Expression Modifiers

The assembler supports several modifiers when using relocatable addresses in AVR instruction operands. The general syntax is the following:

         modifier(relocatable-expression)

`lo8`
  This modifier allows you to use bits 0 through 7 of an address expression as 8 bit relocatable expression.
`hi8`
  This modifier allows you to use bits 7 through 15 of an address expression as 8 bit relocatable expression. This is useful with, for example, the AVR ‘`ldi`’ instruction and ‘`lo8`’ modifier.

  For example

                ldi r26, lo8(sym+10)
                ldi r27, hi8(sym+10)

`hh8`
  This modifier allows you to use bits 16 through 23 of an address expression as 8 bit relocatable expression. Also, can be useful for loading 32 bit constants.
`hlo8`
  Synonym of ‘`hh8`’.
`hhi8`
  This modifier allows you to use bits 24 through 31 of an expression as 8 bit expression. This is useful with, for example, the AVR ‘`ldi`’ instruction and ‘`lo8`’, ‘`hi8`’, ‘`hlo8`’, ‘`hhi8`’, modifier.

  For example

                ldi r26, lo8(285774925)
                ldi r27, hi8(285774925)
                ldi r28, hlo8(285774925)
                ldi r29, hhi8(285774925)
                ; r29,r28,r27,r26 = 285774925

`pm_lo8`
  This modifier allows you to use bits 0 through 7 of an address expression as 8 bit relocatable expression. This modifier useful for addressing data or code from Flash/Program memory. The using of ‘`pm_lo8`’ similar to ‘`lo8`’.
`pm_hi8`
  This modifier allows you to use bits 8 through 15 of an address expression as 8 bit relocatable expression. This modifier useful for addressing data or code from Flash/Program memory.
`pm_hh8`
  This modifier allows you to use bits 15 through 23 of an address expression as 8 bit relocatable expression. This modifier useful for addressing data or code from Flash/Program memory.