// Based upon the example code from NES 101 tutorial by Michael Martin
// compile with -t nes_small
import nes_joy1_default
void main() {
init_graphics()
init_input()
init_sound()
ppu_ctrl = %10001000
ppu_mask = %00011110
while(true){}
}
void nmi() {
scroll_screen()
update_sprite()
react_to_input()
}
void irq() {
}
array oam_buffer [256] @$200
byte scroll
byte a
sbyte dx
void init_graphics() {
init_sprites()
load_palette()
load_name_tables()
init_scrolling()
}
void init_input() {
a = 0
}
void init_sound() {
apu_status = 1
apu_pulse1_sweep = 0
apu_frame_counter = $40
}
void init_sprites() {
byte i
for i,255,downto,0 {
oam_buffer[i] = 0
}
oam_buffer[0] = $70
oam_buffer[1] = 1
oam_buffer[3] = 1
dx = 1
}
void load_palette() {
byte i
ppu_set_addr($3f00)
for i,0,until,palette.length {
ppu_write_data(palette[i])
}
}
void load_name_tables() {
pointer p
byte page_count
byte b
read_ppu_status()
p = bg.addr
ppu_set_addr($2400)
for page_count,0,until,4 {
for b,0,until,255 {
ppu_write_data(p[b])
}
p.hi += 1
}
for page_count,0,until,4 {
for b,0,until,255 {
ppu_write_data(0)
}
}
}
void init_scrolling() {
scroll = 240
}
void update_sprite() {
ppu_oam_dma_write(oam_buffer.addr.hi)
if oam_buffer[3] == 0 {
dx = 1
high_c()
} else if oam_buffer[3] == 255-8 {
dx = -1
high_c()
}
oam_buffer[3] += dx
}
void react_to_input() {
read_joy()
if input_a != 0 { // A button
reverse_dx()
}
if input_dy < 0 { // Up button
if oam_buffer[0] > 7 { oam_buffer[0] -= 1}
}
if input_dy > 0 { // Down button
if oam_buffer[0] < 223 { oam_buffer[0] += 1}
}
}
void reverse_dx() {
dx = 0 - dx
low_c()
}
void low_c() {
apu_pulse1_ctrl = $84
apu_pulse1_period = $9AA
}
void high_c() {
apu_pulse1_ctrl = $86
apu_pulse1_period = $869
}
void scroll_screen() {
ppu_write_data(0)
if scroll != 0 {
scroll -= 1
ppu_set_scroll(0, scroll)
}
}
array bg = [
" " ascii,
"12345678901234567890123456789012" ascii,
" " ascii,
" " ascii,
" PRESENTING NES 101 " ascii,
" A GUIDE FOR OTHERWISE " ascii,
" EXPERIENCED PROGRAMMERS " ascii,
" " ascii,
" TUTORIAL FILE BY " ascii,
" MICHAEL MARTIN " ascii,
" " ascii,
" " ascii,
" " ascii,
" PRESS UP AND DOWN TO SHIFT " ascii,
" THE SPRITE " ascii,
" " ascii,
" PRESS A TO REVERSE DIRECTION" ascii,
" " ascii,
" " ascii,
" " ascii,
" " ascii,
" " ascii,
" " ascii,
"CHARACTER SET HIJACKED FROM " ascii,
"COMMODORE BUSINESS MACHINES " ascii,
" (C64'S CHARACTER ROM)" ascii,
" " ascii,
"READY. " ascii,
" " ascii,
" " ascii,
$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,
$00,$00,$00,$00,$00,$00,$00,$00,$F0,$F0,$F0,$F0,$F0,$F0,$F0,$F0,
$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$0F,$0F,$0F,$0F,$0F,$0F,$0F,$0F
]
array palette = [
$0E,$00,$0E,$19,$00,$00,$00,$00,$00,$00,$00,$00,$01,$00,$01,$21,
$0E,$20,$22,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00
]
segment(chrrom)
array charset @$0200 = [
$00,$00,$00,$00,$00,$00,$00,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$18,$18,$18,$18,$00,$00,$18,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$66,$66,$66,$00,$00,$00,$00,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$66,$66,$FF,$66,$FF,$66,$66,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$18,$3E,$60,$3C,$06,$7C,$18,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$62,$66,$0C,$18,$30,$66,$46,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$3C,$38,$67,$66,$3F,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$06,$0C,$18,$00,$00,$00,$00,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$0C,$18,$30,$30,$30,$18,$0C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$30,$18,$0C,$0C,$0C,$18,$30,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$66,$3C,$FF,$3C,$66,$00,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$18,$18,$7E,$18,$18,$00,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$00,$00,$00,$00,$18,$18,$30,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$00,$00,$7E,$00,$00,$00,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$00,$00,$00,$00,$18,$18,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$03,$06,$0C,$18,$30,$60,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$6E,$76,$66,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$18,$18,$38,$18,$18,$18,$7E,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$06,$0C,$30,$60,$7E,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$06,$1C,$06,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$06,$0E,$1E,$66,$7F,$06,$06,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$7E,$60,$7C,$06,$06,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$60,$7C,$66,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$7E,$66,$0C,$18,$18,$18,$18,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$66,$3C,$66,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$66,$3E,$06,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$00,$18,$00,$00,$18,$00,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$00,$18,$00,$00,$18,$18,$30,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$0E,$18,$30,$60,$30,$18,$0E,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$00,$7E,$00,$7E,$00,$00,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$70,$18,$0C,$06,$0C,$18,$70,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$06,$0C,$18,$00,$18,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$6E,$6E,$60,$62,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$18,$3C,$66,$7E,$66,$66,$66,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$7C,$66,$66,$7C,$66,$66,$7C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$60,$60,$60,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$78,$6C,$66,$66,$66,$6C,$78,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$7E,$60,$60,$78,$60,$60,$7E,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$7E,$60,$60,$78,$60,$60,$60,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$60,$6E,$66,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$66,$66,$66,$7E,$66,$66,$66,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$18,$18,$18,$18,$18,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$1E,$0C,$0C,$0C,$0C,$6C,$38,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$66,$6C,$78,$70,$78,$6C,$66,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$60,$60,$60,$60,$60,$60,$7E,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$63,$77,$7F,$6B,$63,$63,$63,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$66,$76,$7E,$7E,$6E,$66,$66,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$66,$66,$66,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$7C,$66,$66,$7C,$60,$60,$60,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$66,$66,$66,$3C,$0E,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$7C,$66,$66,$7C,$78,$6C,$66,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$66,$60,$3C,$06,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$7E,$18,$18,$18,$18,$18,$18,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$66,$66,$66,$66,$66,$66,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$66,$66,$66,$66,$66,$3C,$18,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$63,$63,$63,$6B,$7F,$77,$63,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$66,$66,$3C,$18,$3C,$66,$66,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$66,$66,$66,$3C,$18,$18,$18,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$7E,$06,$0C,$18,$30,$60,$7E,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$30,$30,$30,$30,$30,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$0C,$12,$30,$7C,$30,$62,$FC,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$3C,$0C,$0C,$0C,$0C,$0C,$3C,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$18,$3C,$7E,$18,$18,$18,$18,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF,
$00,$10,$30,$7F,$7F,$30,$10,$00,$FF,$FF,$FF,$FF,$FF,$FF,$FF,$FF
]
segment(chrrom)
array sprites @$1000 = [
$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,
$18,$24,$66,$99,$99,$66,$24,$18,$00,$18,$18,$66,$66,$18,$18,$00
]