4is256 by Řrřola [web]
; * ** %%% ### 4is256
; * % @@@@ ** % # a 256-byte brick game
; **%% # == @@ by Rrrola
; % ==== ### == @@ <rrrola@gmail.com>
; STORY
; confused bricks fall down the pit of sorrow
; show them the rightful way of flawless rows
; make them complete
; make them disappear in joy
; and get awarded for their redemption
; CONTROLS AND SHIFTS
; left shift ......... move left
; right shift ....... move right
; ctrl .............. rotate ccw
; alt .............. fall faster
; SCORING
; fast falling ........... 1/row
; deleted rows ... 32/96/160/224
; don't delete too fast ... -256 (punishment for the greedy ;-))
; LEVEL (FALLING SPEED)
; increases every (1<<level) deletions
; note: needs vertical retrace for timing (fullscreen or pure DOS)
; greets to everyone who JUST WOULDN'T GET THE STRAIGHT ONE OMGWTF
HEIGHT equ 24 ; must be a multiple of 4
WIDTH equ 10 ; 4..23
PIT_CHAR equ 'º'
BRICK_CHAR equ 'Û'
org 100h ; assume ax=0 bl=0 sp=0FFFEh
inc ax
int 10h
mov ah,5 ; textmode 40x25, page 1 (offset 800h)
int 10h ; filled with gray spaces on black (0720h)
push word 0B800h
pop es
push es
pop ds
; Draw the pit and erase complete rows
P:
mov di,2178+(HEIGHT-1)*80
mov si,di ;-) si = source row, di = destination row
mov cx,HEIGHT+4
E:
sub di,byte 80
N:
add bl,64 ; score += {0,64,128,192}[erased rows mod 4]
sub si,byte 80+WIDTH*2
mov ax,800h+PIT_CHAR
stosw
sub di,byte WIDTH*2+4
stosw
mov dx,WIDTH
A:
or [di+(HEIGHT+4)*80+1],ah
and al,[si+1]
movsw ; white score at the bottom of the pit, shift rows
dec dx
jnz A
and al,8 ; brightness all the way?
jnz N
loop E
cmp si,di ; if any rows were deleted, adjust score to +32/96/160/224
je G
sub bl,32
dec sp ; sp = 0FFFEh-total deletions
; Generate a new brick
G: ; di=6F2h cx=0
in al,40h; could be "rdtsc" for hardcore randomness
mov ah,5Ah
mul di ; dx:ax=2711400h..277FF0Eh
mov bp,dx
mov cl,[byte bp-271h+S]
mov di,800h-160+48-(WIDTH|1)
mov si,es ;-) the highest bits of si need to be "10"
; bp = brick index + 271h
; cx = rotated brick layout (4 bits per row)
; di = brick position
; most significant zero bit in sp = number of frames before dropping
; (si is used for checking that)
; Increase the displayed score by 1
M:
or bl,bl
jz V
push di ; di = behind the last zero
mov di,800h+HEIGHT*80+50
dec bx
D:
dec di ; next digit
dec di
mov al,'0'; assume overflow
xchg al,[di]
or al,10h
cmp al,'9'
je D
inc ax
stosb ; if the digit wasn't '9', raise it
pop di
; Wait for vertical retrace start (70/sec) and erase the brick
V:
mov dx,3DAh
in al,dx
and al,8
jz V
W:
in al,dx
and al,8
jnz W ; al=0
call B ; if not erasable (= has no space to appear), GAME OVER
jnc near 0
; Keyboard handler
mov ah,2
int 16h
and bh,al ; bh = previous shift state
xchg al,bh
not bh ; if a shift was just pressed, set a bit in al
pusha
shr al,1 ; RSHIFT: X++
jnc X
scasw ; di+=2
X:
shr al,1 ; LSHIFT: X--
jnc Y
dec di
dec di
Y:
shl ax,15
jnc F ; ALT: Y++, score++
inc bx
mov bh,8 ; can be held until landing
H:
mov si,sp
add si,byte 16
add di,byte 80
F:
jns C ; CTRL: rotation
R: ; ax=8000h, CF=0
rcl cx,13 ; ax = cx rotated 90 degress ccw around [1;1]
rcr ax,1
jnc R
cmp ah,[byte bp-271h+S]
je I ; if we reach the original shape, reload (for O,S,Z)
ror ax,12
I:
xchg ah,al
xchg ax,cx
C: ; al=0
; Test whether changes were OK, drop if it's time
call B
jnc Q
add sp,byte 16
pusha
Q:
popa ; use [bp-7*16] for black background instead of gray
lea ax,[bp+0]
rol si,1 ; OF = (CF!=sign(si))
jnc L ; you can't land with alt only (less mistakes)
push word M
jno B ; doesn't have to fall: draw the brick
pop ax ; has to fall: clean the stack
xor ax,ax
pusha
jmp short H
L:
or al,8 ; draw the fallen brick bright and generate next brick
push word P
; Brick drawing (al=color cx=shape di=address)
B:
push bx
xor bx,bx
T:
ror cx,1
jnc skip ; brightness prevents drawing
test byte[bx+di],8 ; CF=0
jnz O
mov [bx+di],al
mov byte[bx+di-1],BRICK_CHAR
skip:
inc bx
inc bx ; bl:00 02 04 06 08
test bl,8 ; 50 52 54 56 58
jz T ; A0 A2 A4 A6 A8
add bl,72 ; F0 F2 F4 F6 F8 40+CF
jnc T
O:
pop bx ; if the brick could be drawn, CF=1
ret
; .... ##.. ..#. #... .##. .#.. ##..
; #### .##. ###. ###. ##.. ###. ##..
S: db 0F0h, 63h, 74h, 71h, 36h, 72h, 33h
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