.ifndef INCLUDE_MEMCOPY
INCLUDE_MEMCOPY = 1

.include "system.h65"

.export memcopy,memcopy16

.code
;;********************************************************************************
;; @function Copy a block of memory to a different address
;; @param ARG0-1: Source address
;; @param ARG2-3: Target address
;; @param Y: Number of bytes to copy
;; @modifies: A,Y
;;********************************************************************************
.proc memcopy
    cpy #0
    beq @rts
@copy_byte:
    dey
    lda (ARG0),y
    sta (ARG2),y
    cpy #0
    bne @copy_byte
@rts:
    rts
.endproc

;;********************************************************************************
;; @function Copy a block of memory to a different address
;; @param ARG0-1: Source address
;; @param ARG2-3: Target address
;; @param ARG5-6: Number of bytes to copy (LE)
;; @modifies: A,Y
;;********************************************************************************
.proc memcopy16
    lda ARG6
    beq @last_page  ; no full page
    ldy #$ff
    bra @copy_byte
@next_page:   ; y is 0
    lda ARG6
    beq @rts  ; done
    inc ARG1
    inc ARG3
    dec ARG6
    beq @last_page
    ldy #$ff
@copy_byte:
    lda (ARG0),y
    sta (ARG2),y
@dec_y:
    dey
    beq @next_page
    bra @copy_byte
@last_page:
    ldy ARG5
    dey
    bra @copy_byte
@rts:
    rts
.endproc

.endif  ; guard