The original enlarger was a simple BASIC program that demonstrated how to enlarge an object, but was horribly slow. This is the assembler version that drastically improves the speed and adds a couple more pictures.
;
; Enlarger ASM
; v1.00 Steven Reid (c) 2022
;
; A rewrite of my old BASIC program that does a simple
; enlarge routine. Nothing exciting, just thought I'd
; try to speed it up. Will see if I can make something
; of this;
;
; 1/25/2022 - Initial build.
;
; +++
;
; Header and startup
;
; start up stuff
org 16514 ; stored in REM at top (ZX81)
jr start ; needed for z80asm
; title and copyright (will show on listing)
copy:
db $2a,$33,$31,$26,$37,$2c,$2a,$37,$00,$26
db $38,$32,$17,$17,$38,$31,$37,$18,$1e,$1e
db $17,$76,$76
; **ENLARGER ASM**SLR/2022**
start:
call slow ; SLOW is required.
; end header and startup
;
; ---
; +++
;
; Main Loop
;
mainloop:
; print first screen
call cls
ld hl,intro
call print
ld hl,moon
call print
ld hl,intent
call print
ld hl,8000
call newpause
; enlarge moon
ld hl,moon
call enlarger
ld bc,$0000
call printat
ld hl,done
call print
ld hl,8000
call newpause
; enlarge moon with crators
ld hl,mooncrater
call enlarger
ld hl,8000
call newpause
; enlarge a bee
ld hl,bee
call enlarger
ld hl,8000
call newpause
jp mainloop
; End of loop!
;
; +++
;
; Routines
;
;
; Print string at HL
; stops when reaches $FF
;
print:
ld a,(hl) ; load character
inc hl ; increment memory
cp $ff ; last character?
ret z ; yep, return
rst $10 ; nope, print it!
jr print ; loop
;
; Copy buffer to screen
;
copy2screen:
ld de,(d_file)
inc de ; skip initial newline
ld hl,buffer
ld bc,726 ; 22 lines with 32char+return
ldir
ret
;
; Copy screen to buffer
;
copy2buffer:
ld de,buffer
ld hl,(d_file)
inc hl ; skip initial newline
ld bc,726 ; 22 lines with 32char+return
ldir
ret
;
; Clear buffer
;
clearbuffer:
ld de,emptyline-33
ld hl,emptyline
ld a,21
cbloop:
ld bc,33
lddr
dec a
jp nz,cbloop
ret
;
; Delay
;
; set bc to speed
; press space to
pframe: dw $0000
newpause:
ld (pframe),hl
call kscan ; get key press
inc l
jr z,lppause ; not yet loop
dec l
ld b,h
ld c,l
call findchar ; yep, grab character pressed
ld a,(hl)
push af
call wait
pop af
and a ; pressed space (break)
jp z,stop ; stop!
ret ; or return!
; loop!
lppause:
ld hl,(pframe)
dec hl
ld a,h
or l
jr nz,newpause ; not zero, keep going!
ret ; pause is done!
wait: call kscan ; Wait for human to take finger off of key.
inc l
jr nz,wait
ret
;
; Enlarge
;
;
; Original basic below
;
; Really just walks the array. It assumes full
; lines (32 characters). The routine basically
; walks the first 16 characters of each line
; and expands it into 4 characters. This dobules
; each character. It then skips down and does
; the same for each line. It isn't very optimized.
;
; 110 DIM B$((LEN A$)*4)
; 130 LET L=1
; 140 FOR B=1 TO (LEN A$) STEP 32
; 145 FOR C=B TO B+15-((B+15-(
;LEN A$)) AND B+15>LEN A$)
; 150 LET B$(L)=A$(C)
; 160 LET B$(L+1)=A$(C)
; 170 LET B$(L+32)=A$(C)
; 180 LET B$(L+33)=A$(C)
; 190 LET L=L+2
; 200 NEXT C
; 210 LET L=L+32
; 220 NEXT B
;
; for the assembly version, I just assume
; I'm exapsnding from the left edge. That
; means I go 16 across and 11 down. Easy!
enlarge:
; call clearbuffer ; clear the buffer first
ld de,buffer ; enlarge to here
ld hl,(d_file) ; from the screen
inc hl
ld b,11 ; 11 rows
yloop:
push bc
ld b,16 ; 15 cols
xloop:
push bc
ld a,(hl) ; grab char (usually $80 or $00)
inc hl ; next char on screen
ex de,hl ; exchange de and hl
push hl ; save current buffer position
; this is the enlarge routine
ld (hl),a ; set hl to a
inc hl ; next char
ld (hl),a ; set hl to a
ld bc,32
add hl,bc ; skip to next row
ld (hl),a ; set hl to a
inc hl ; next char
ld (hl),a ; set hl to a
pop hl ; restore buffer
inc hl ; and move ahead 2
inc hl
ex de,hl ; exchange it back
pop bc ; then loop!
djnz xloop
ld bc,17 ; skip to next screen line
add hl,bc
ex de,hl
ld bc,34 ; jump down start of 2 lines
add hl,bc
ex de,hl
pop bc ; then loop!
djnz yloop
jp copy2screen ; copy to screen
;
; Enlarger - pass what to enlarge in hl
;
enlarger:
; print moon
push hl
call cls
pop hl
call print
ld hl,500
call newpause
; enlarge things!
ld b,5
enloop:
push bc ; save loop
; make bigg4er and print it!
call enlarge ; make bigger
ld hl,500
call newpause
pop bc ; restore loop
djnz enloop ; loop until done
ret
; end routines
; ---
; +++
;
; Data and Defines
;
; ZX81 system vars
d_file: equ $400c
d_fcc: equ 16398
frames: equ 16436
; ZX81 ROM functions
kscan: equ $02bb
findchar: equ $07bd
stop: equ $0cdc
slow: equ $0f2b
fast: equ $02e7
save: equ $02f9
printat: equ $08f5
pause: equ $0f35
cls: equ $0a2a
; end defines
; ---
; +++
; Data
;
;
; messages
;
intro:
db $3c,$2a,$00,$38,$2d,$26,$31,$31,$00,$2a
db $33,$31,$26,$37,$2c,$2a,$00,$26,$00,$35
db $2e,$28,$39,$3a,$37,$2a,$00,$34,$2b,$00
db $26,$00
; WE SHALL ENLARGE A PICTURE OF
db $32,$34,$34,$33,$1b,$00,$00,$00,$00,$00
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00
db $00,$00
; A MOON.
db $ff
moon:
db $00,$00,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$80,$80,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $80,$80,$80,$80,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $80,$80,$80,$80,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$80,$80,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $ff
mooncrater:
db $00,$00,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$80,$80,$08,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $80,$08,$80,$80,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $80,$80,$80,$80,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$80,$08,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$80,$08,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $ff
bee:
db $80,$00,$80,$80,$00,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$80,$08,$08,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $80,$80,$80,$80,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$08,$08,$08,$08,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$80,$80,$80,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $80,$00,$08,$08,$00,$80,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $ff
intent:
db $34,$30,$1a,$00,$39,$34,$00,$2a,$33,$31
db $26,$37,$2c,$2a,$00,$39,$2d,$2a,$00,$32
db $34,$34,$33,$00,$3c,$2a,$00,$3c,$2e,$31
db $31,$00
; OK, TO ENLARGE THE MOON WE WILL
db $39,$26,$30,$2a,$00,$2a,$26,$28,$2d,$00
db $38,$36,$3a,$26,$37,$2a,$00,$26,$33,$29
db $00,$32,$3a,$31,$39,$2e,$35,$31,$3e,$00
db $2e,$39
; TAKE EACH SQUARE AND MULTIPLY IT
db $27,$3e,$00,$20,$00,$32,$26,$30,$2e,$33
db $2c,$00,$26,$00,$31,$26,$37,$2c,$2a,$37
db $00,$35,$2e,$28,$39,$3a,$37,$2a,$1b,$00
db $00,$00
; BY 4 MAKING A LARGER PICTURE.
presskey:
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00
db $00,$00
db $35,$37,$2a,$38,$38,$00,$2a,$33,$39,$2a
db $37,$00,$39,$34,$00,$27,$2a,$2c,$2e,$33
db $1b,$1b,$1b,$ff
; PRESS ENTER TO BEGIN...
done:
db $39,$2d,$26,$39,$00,$3c,$26,$38,$00,$26
db $00,$38,$28,$26,$31,$2a,$00,$2a,$33,$31
db $26,$37,$2c,$2a,$32,$2a,$33,$39,$00,$34
db $2b,$00
; THAT WAS A SCALE ENLARGEMENT OF
db $26,$00,$32,$34,$34,$33,$1b,$00,$00,$33
db $34,$39,$00,$3b,$2a,$37,$3e,$00,$38,$35
db $2a,$28,$39,$26,$28,$3a,$31,$26,$37,$1a
db $00,$00
; A MOON. NOT VERY SPECTACULAR,
db $27,$3a,$39,$1a,$00,$2e,$2b,$00,$34,$33
db $2a,$00,$28,$34,$3a,$31,$29,$00,$32,$34
db $29,$2e,$2b,$3e,$00,$39,$2d,$2e,$38,$00
db $00,$00
; BUT, IF ONE COULD MODIFY THIS
db $38,$2e,$32,$35,$31,$2a,$00,$35,$37,$34
db $2c,$37,$26,$32,$1a,$00,$39,$2d,$2a,$00
db $2a,$2b,$2b,$2a,$28,$39,$00,$28,$34,$3a
db $31,$29
; SIMPLE PROGRAM, THE EFFECT COULD
db $27,$2a,$00,$27,$34,$39,$2d,$00,$3a,$38
db $2a,$2b,$3a,$31,$00,$26,$33,$29,$00,$38
db $35,$2a,$28,$39,$26,$28,$3a,$31,$26,$37
db $1b,$76
; BE BOTH USEFUL AND SPECTACULAR.
db $ff
;
; screen buffer
;
buffer:
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
emptyline:
db $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$76
; end data
; ---