;helper routines for arithmetic on 32 bit numbers 

;reuse the copy_* zero page locations as pointers for 32bit addition
.importzp copy_src
.importzp copy_dest

acc32 =copy_src       ;32bit accumulater (pointer)
op32 =copy_dest       ;32 bit operand (pointer)

.exportzp acc32
.exportzp op32
.export add_32_32
.export add_16_32

;add a 32bit operand to the 32 bit accumulater
;acc32=acc32+op32
add_32_32:
  clc
  ldy #0
  lda (op32),y
  adc (acc32),y
  sta (acc32),y  
  iny
  lda (op32),y
  adc (acc32),y
  sta (acc32),y  
  iny
  lda (op32),y
  adc (acc32),y
  sta (acc32),y  
  iny
  lda (op32),y
  adc (acc32),y
  sta (acc32),y  
    
  rts
  

;add a 16bit operand to the 32 bit accumulater
;acc32=acc32+AX
add_16_32:
  clc
  ldy #0
  adc (acc32),y
  sta (acc32),y  
  iny
  txa
  adc (acc32),y
  sta (acc32),y  
  iny
  lda #0
  adc (acc32),y
  sta (acc32),y
  iny
  lda #0
  adc (acc32),y
  sta (acc32),y
  rts