; GAME 1 - Land Me ; by Krzysztof Krystian Jankowski ^ P1X ; [bits 16] [org 0x7c00] ; ======== MEMORY POINTERS ======== VGA equ 0xA000 TIMER equ 046Ch BUFFER equ 0x1000 ; 64000 MEM_BASE equ 0x7e00 MEM_SKY equ MEM_BASE ; 2 MEM_MIRROR equ MEM_BASE+2 ; 32 MEM_PLAYER_POS equ MEM_BASE+4 MEM_CURRENT_LEVEL equ MEM_BASE+6 MEM_BOAT_ANIM equ MEM_BASE+8 MEM_BOAT_DIR equ MEM_BASE+10 MEM_LIFES equ MEM_BASE+12 ; ======== SETTINGS ======== PLAYER_COLOR equ 31 SKY_COLOR equ 82 PLATFORM_COLOR equ 39 BOAT_COLOR equ 53 BOAT_POSITION equ 320*187+120 BOAT_WIDTH equ 80 BOAT_HEIGHT equ 3 SPRITE_SIZE equ 14 DEATH_ROW equ 198 PLAYER_START equ 320*6+150 LEVEL_SIZE equ 5 PLATFORM_HEIGHT equ 6 LEVELS equ 3 ; ======== GRAPHICS INITIALIZATION ======== start: xor ax,ax ; Init segments (0) mov ds, ax mov ax, VGA ; Set VGA memory mov es, ax ; as target mov ax, 13h ; Init VGA int 10h mov ax, BUFFER ; Set double buffer mov es, ax ; as target ; ======== GAME RESTART ======== restart_game: mov word [MEM_PLAYER_POS], PLAYER_START cmp byte [MEM_LIFES], 0 jz .game_over .restart_player: dec byte [MEM_LIFES] jmp game_loop .game_over: mov word [MEM_CURRENT_LEVEL],0 xor word [MEM_MIRROR], 1 mov word [MEM_BOAT_ANIM], 0 mov byte [MEM_SKY], SKY_COLOR mov byte [MEM_LIFES], 3 jmp game_loop ; ======== NEXT LEVEL ======== next_level: cmp word [MEM_CURRENT_LEVEL], LEVELS ja restart_game inc word [MEM_CURRENT_LEVEL] mov word [MEM_PLAYER_POS], PLAYER_START mov word [MEM_BOAT_ANIM], 0 add byte [MEM_SKY], 64 ; ======== GAME LOOP ======== game_loop: ; ======== DRAW MEM_SKY ======== draw_bg: xor di, di ; Reset DI mov cx, 200 ; Repeat for full screen height .draw_line: ; Decide on start color mov bx, [MEM_SKY] ; Set color to MEM_SKY mov ax, cx ; Copy line number to AX and ax, 0xFF ; Clear all but 0xFF shr ax, 4 ; Shift 4 times = div by 16 (200/16 = 12px band) add bx, ax ; Shift current color intex (BX) ; Drawing push cx ; Save loop counter mov al, bl ; Set color (from BX) mov cx, 320 ; Set length (full screen width line) rep stosb ; Send colors to frame buffer pop cx ; Load loop counter loop .draw_line ; ======== DRAW OCEAN ======== draw_ocean: sub di, 320*20 mov cx, 20 mov bl, 52 .draw_row: push cx mov cx, 320 xor bl, 4 mov al, bl mov dx, 320 rep stosb pop cx loop .draw_row ; ======== DRAW LIFES ======== xor di, di add di, 320+80 mov bx, 0 mov cx, [MEM_LIFES] inc cx draw_life: push cx mov al, 12 mov cx, 40 ; Set length (full screen width line) rep stosb ; Send colors to frame buffer pop cx loop draw_life ; ======== DRAW LEVEL ======== draw_level: xor di, di mov bx, [MEM_CURRENT_LEVEL] mov ax, LEVEL_SIZE mul bx mov si, level_data add si, ax ; Move to correct level ; ======== BOAT ======== mov bh, BOAT_COLOR ; Draw boat platform mov ax, BOAT_POSITION add ax, [MEM_BOAT_ANIM] add di, ax mov cx, BOAT_HEIGHT mov ax, BOAT_WIDTH jmp .draw_platform .read_next_platform: lodsb ; Load pos test ax, ax jz done ; If 0, end of data movzx ax, al ; Zero-extend AL to AX for multiplication (x value) imul ax, 20 ; Fit to grid mov bx, ax ; Store result in BX temporarily movzx ax, ah ; Zero-extend AH to AX for multiplication (y value) imul ax, 10 ; Fit to grid imul ax, 320 add ax, bx ; AX = final offset in the framebuffer mov di, ax ; Move calculated offset into DI mov ax, [MEM_CURRENT_LEVEL] ; Width of platform add ax, 2 ; Current level + 2 imul ax, 20 ; Fit to grid mov bh, PLATFORM_COLOR mov cx, PLATFORM_HEIGHT .draw_platform: push cx ; Save loop counter push ax ; Save length mov cx, ax mov al, bh inc bh ; move color rep stosb ; Draw line pop ax add di, 319 sub ax, 2 sub di, ax pop cx ; Restore loop counter loop .draw_platform jmp .read_next_platform ; Process next segment done: ; ======== ANIMATE BOAT ======== animate_boat: cmp byte [MEM_BOAT_DIR], 0 jnz .sail_left .sail_right: add word [MEM_BOAT_ANIM], 2 jmp .done .sail_left: sub word [MEM_BOAT_ANIM], 2 cmp word [MEM_BOAT_ANIM], -80 jz .reverse .done: cmp byte [MEM_BOAT_ANIM], 80 jl collision_check .reverse: xor byte [MEM_BOAT_DIR], 1 ; ======== COLLISION CHECKING ======== collision_check: mov bx, SPRITE_SIZE add ax, 320 ; Check below sprite top pos mul bx add word ax, [MEM_PLAYER_POS] ; Add x-coordinate cmp ax, 320*DEATH_ROW ; Check if drop to the ocean ja restart_game mov di, ax ; Store in DI for ES:DI addressing sub di, SPRITE_SIZE/2 mov cx, SPRITE_SIZE .chk: mov ah, [es:di] cmp ah, PLATFORM_COLOR je restart_game cmp ah, BOAT_COLOR je next_level inc di loop .chk add word [MEM_PLAYER_POS], 320 ; Fall 1px down run: .check_run_dir: cmp byte [MEM_MIRROR], 0 je .run_right .run_left: dec word [MEM_PLAYER_POS] jmp .continue_run .run_right: inc word [MEM_PLAYER_POS] .continue_run: ; ======== DRAW PLAYER ======== draw_player: mov word ax, [MEM_PLAYER_POS] ; Add x-coordinate mov di, ax ; Store in DI for ES:DI addressing push di mov bh, PLAYER_COLOR xor ax, ax mov cx, SPRITE_SIZE .draw_row: push cx ; Save loop counter push ax ; Save length mov cx, ax mov al, bh rep stosb pop ax cmp ax, SPRITE_SIZE/2 jge .skip_enlarge add di, 321 add ax, 2 jmp .finish_row .skip_enlarge: dec bh add di, 320 .finish_row: sub di, ax ; Move line down pop cx ; Restore loop counter loop .draw_row ; ======== KEYBOARD ======== .handle_keyboard: mov ah, 0x01 ; Check if a key has been pressed int 0x16 jz .no_kb ; Jump if no key is in the keyboard buffer xor ax,ax ; Get the key press int 0x16 ; REMOVE ME ; cmp ah, 0x01 ; Check if the scan code is for the [Esc] key ; je restart_game ; cmp ah, 0x1C ; Check if the scan code is for the [Esc] key ; je next_level ; /REMOVE ME sub word [MEM_PLAYER_POS], 320 xor byte [MEM_MIRROR], 1 ; swap direction .no_kb: ; ======== BLIT ======== blit: push es push ds mov ax, 0xA000 ; VGA memory mov bx, BUFFER ; Buffer memory mov es, ax mov ds, bx mov cx, 32000 ; Half of the buffer xor si, si xor di, di rep movsw pop ds pop es ; ======== DELAY ======== delay_timer: mov ax, [TIMER] inc ax .wait: cmp [TIMER], ax jl .wait jmp game_loop ; ======== LEVELS ======== level_data: ; 5b db 73 db 85 db 121 db 149 db 0 ; End of level level_2: db 56 db 106 db 117 db 184 db 0 ; End of level level_3: db 57 db 101 db 168 db 195 db 0 ; End of level level_4: db 132 ; Continue read positions from P1X 80,50,88... db 'P1X' ; P1X signature 3b db 0 ; ======== BOOTSECTOR ======== TIMES 510 - ($ - $$) DB 0 ; Fill empty space (512) - signatures (5b) DW 0xAA55 ; Bootsector 2b