dos33fsprogs/demos/xmas_2019/gr_copy.s

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;=========================================================
; gr_copy_to_current, 40x48 version
;=========================================================
; copy 0xc00 to DRAW_PAGE
;
; 45 + 2 + 120*(8*9 + 5) -1 + 6 = 9292
gr_copy_to_current:
lda DRAW_PAGE ; 3
clc ; 2
adc #$4 ; 2
sta gr_copy_line+5 ; 4
sta gr_copy_line+11 ; 4
adc #$1 ; 2
sta gr_copy_line+17 ; 4
sta gr_copy_line+23 ; 4
adc #$1 ; 2
sta gr_copy_line+29 ; 4
sta gr_copy_line+35 ; 4
adc #$1 ; 2
sta gr_copy_line+41 ; 4
sta gr_copy_line+47 ; 4
;===========
; 45
ldy #119 ; for early ones, copy 120 bytes ; 2
gr_copy_line:
lda $C00,Y ; load a byte (self modified) ; 4
sta $400,Y ; store a byte (self modified) ; 5
lda $C80,Y ; load a byte (self modified) ; 4
sta $480,Y ; store a byte (self modified) ; 5
lda $D00,Y ; load a byte (self modified) ; 4
sta $500,Y ; store a byte (self modified) ; 5
lda $D80,Y ; load a byte (self modified) ; 4
sta $580,Y ; store a byte (self modified) ; 5
lda $E00,Y ; load a byte (self modified) ; 4
sta $600,Y ; store a byte (self modified) ; 5
lda $E80,Y ; load a byte (self modified) ; 4
sta $680,Y ; store a byte (self modified) ; 5
lda $F00,Y ; load a byte (self modified) ; 4
sta $700,Y ; store a byte (self modified) ; 5
lda $F80,Y ; load a byte (self modified) ; 4
sta $780,Y ; store a byte (self modified) ; 5
dey ; decrement pointer ; 2
bpl gr_copy_line ; ; 2nt/3
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gr_copy_line_end:
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rts ; 6
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.assert >gr_copy_line = >gr_copy_line_end, error, "gr_copy_to_current crosses page"