Still trying to formulate some opinions about these, routines seem to be good for saving memory (haha) and keeping the listing file readable, while macros seem to be good for abstracting expressions that leverage assembler features like 'high()','low()', or 'x*2'

AvrAssembly_PreprocessorVsAsmMacros.as

;
;  Output file in intel hex format with -fI
;
;  wine avrasm2.exe -fI -l test.lst test.asm and; avrdude -c usbtiny -p atmega1284 -U flash:w:test.hex
;

.nolist
.include "./m1284def.asm"
.list

;.macro outi
;  push r30
;  ldi r30,@1
;  out @0,r30
;  pop r30
;.endm

#define outi(destination,value) \
  push r30                      \
  ldi r30,(value)               \
  out (destination),r30         \
  pop r30

.cseg ;Code (flash) segment ;This is added by default if not written down

  outi(DDRA,0xff)  ; Data direction register
  outi(PortA,0x56)    ; set leds at port

  outi(DDRB,0xff)   ; Data direction register
  outi(PortB,0x56)    ; set leds at port

Main:
  rjmp Main