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soyoil/gbcal.z80

Created September 3, 2020 09:36
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ゲームボーイでカレンダーを表示してみる試み
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gbcal.z80
include "hardware.inc"
section "halt", rom0[$38]
di
halt
stop
section "lcdc status interrupt", rom0[$48]
reti
section "serial interrupt", rom0[$58]
reti
section "keypad interrupt", rom0[$60]
reti
section "header", rom0[$100]
EntryPoint:
nop
jp start
NINTENDO_LOGO
rept $150 - $134
db 0
endr
section "code", rom0[$150]
start:
; Turn off the LCD
.waitVBlank
ld a, [rLY]
cp 144
jr c, .waitVBlank
xor a
ld [rLCDC], a
; Copy font data
ld hl, $9000
ld de, FontTiles
ld bc, FontTilesEnd - FontTiles
.copyFont
ld a, [de]
ld [hli], a
inc de
dec bc
ld a, b
or c
jr nz, .copyFont
; Insert date to memory
ld hl, $C000 ; work RAM
ld de, Date
ld bc, DateEnd - Date
.insertDate
ld a, [de]
ld [hli], a
inc de
dec bc
ld a, b
or c
jr nz, .insertDate
; print current date
ld bc, $C000
ld hl, $9866
.printDate
ld a, [bc]
rept 4
srl a
endr
add a, $30
ld [hli], a
ld a, [bc]
and %00001111
add a, $30
ld [hli], a
inc bc
ld a, $4
cp a, c
jr z, .printDateEnd
ld a, $2
cp a, c
jr nz, .printDate
ld a, [bc]
ld [hli], a
inc bc
jr .printDate
.printDateEnd
; print week
ld hl, $98C0
ld de, Week
ld bc, WeekEnd - Week
.printWeek
ld a, [de]
ld [hli], a
inc de
dec bc
ld a, [de]
ld [hli], a
inc hl
inc de
dec bc
ld a, b
or c
jr nz, .printWeek
; seek head
ld hl, $98E0
ld de, $0003
ld b, $7
.seekHead
dec b
jr z, .seekHeadEnd
add hl, de
jr .seekHead
.seekHeadEnd
; print calender
ld de, $0B
xor a
ld c, $31 ; todo
.printCal
; ----
add a, 1
daa
ld b, a
rept 4
srl a
endr
add a, $30
ld [hli], a
ld a, b
and %00001111
add a, $30
ld [hli], a
ld a, b
inc hl
; ----
push af
ld a, $F5
cp a, l
jr z, .NewLine
rept 5
add a, $20
cp a, l
jr z, .NewLine
endr
jr .NewLineEnd
.NewLine
add hl, de
.NewLineEnd
pop af
cp a, c
jr nz, .printCal
; Init display registers
ld a, %11100100
ld [rBGP], a
xor a
ld [rSCY], a
ld [rSCX], a
; Shut sound down
ld [rNR52], a
; Turn screen on, display background
ld a, %10000001
ld [rLCDC], a
; Lock up
halt
.lockup
jr .lockup
section "Font", rom0
FontTiles:
INCBIN "font.chr"
FontTilesEnd:
section "Const", rom0
Date:
db $20, $20, $2D, $08
DateEnd:
Week:
db "SUMOTUWETHFRSA"
WeekEnd:
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