define SRC_LO  $00
define SRC_HI  $01

define DEST_LO $02
define DEST_HI $03

define temp $04		;temp storage used by foo

;some prep work since easy6502 doesn't allow you to define arbitrary bytes before runtime.

SET_TABLE:
TXA
STA $1000,X
INX
BNE SET_TABLE	
;stores the identity table at memory address $1000-$10FF

CLEAR_TABLE:
LDA #0
STA $1200,X
INX
BNE CLEAR_TABLE
;fills the range $1200-$12FF with zeroes.


LDA #$10
STA SRC_HI
LDA #$00
STA SRC_LO
;store memory address $1000 in zero page

LDA #$12
STA DEST_HI
LDA #$00
STA DEST_LO
;store memory address $1200 in zero page


loop:
LDA (SRC_LO),y  ;load accumulator from memory address $1000+y
JSR foo		;multiplies accumulator by 3.
STA (DEST_LO),y ;store accumulator in memory address $1200+y

INY
CPY #$56 ;alternatively you can store a size variable and check that here instead.
BCC loop
BRK

foo:
STA temp
ASL		;double accumulator
CLC
ADC temp	;2a + a = 3a
RTS