passport/src/memory.clear.a

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2021-07-11 04:51:32 +00:00
; /!\ execution falls through from ChangeTrack
;-------------------------------
; ClearTSBuffer
; clear the $1000 byte memory buffer
; used to store the current track's data
; in: none
; out: Z = 1
; X preserved
; Y = 0
; all other flags and registers clobbered
;-------------------------------
ClearTSBuffer
lda #BASEPAGE
ldx #$00
ldy #$10
; /!\ execution falls through here
;-------------------------------
; ClearMemory
; in: A = source address (high)
; X = value to set
; Y = number of pages
; out: Z = 1
; X preserved
; Y = 0
; all other flags and registers clobbered
;-------------------------------
ClearMemory
sta @dest+2
@dest stx $FF00
inc @dest+1
bne @dest
inc @dest+2
dey
bne @dest
rts