; Mine - 253 byte minesweeper - written by Chris Mumma - 2011 (public domain)
; inspired by James David Chapman and his 256 byte games (TET/INV/BD3)
; Mr Chapman's games can be found at his website:
; http://www.users.globalnet.co.uk/~jchap/tvpro256.htm
; compile with FASM - http://flatassembler.net/
;
; Control with mouse
; Press any key after win/loose to exit game
; Asterisks (*) are mines. If you see one you've lost
;
; Features:
;  40x25 character C0LOR text mode
;  playable with a one button mouse
;  8x8 square board with 8 mines (randomized each game)
;  mouse clicks uncover empty spots with floodfill
;  numbers to indicate nearby mines
;  holding mouse button down while moving the mouse acts like rapid clicks
;  exit game code (press any key after win or loose)
;
; features cut out:
;  all text and user messages
;  flagging mines with right click
;  proper 8-way floodfill
;  game timer
;  adjustable board size
;  mouse driver check`                       
;
; won't run under DosBox as it lacks 100% compatable text mode mouse cursor
; (I understand that. I figure almost no dos games use text mode with a mouse)
; tested and works under windows 7 console (CMD.EXE / NTVDM)
; should run on any 386 based DOS PC but I don't have the resources to do
; extensive testing...

mapSize    equ 8     ; easy mode right? (square maps only)
mineCount  equ 8     ; (16x16 w/40 mines = medium | 24x24 w/90 mines = hard)
mapData    equ heapPtr + 80  ; generated mine map memory offset

org 100h            ; dos .com file program start
    inc ax
    int 10h         ; set 40x25
    int 33h         ; show mouse cursor
;init game map in heap
    mov ah,7            ; set text color
    mov di,mapData - 80
    mov cl,40           ; assume CH = null on entry
    rep stosw           ; line of null (for map clipping)
    mov cl,mapSize
@@: push cx
    mov cl,mapSize      ; square maps only
    mov al,20h          ; empty space marked with space (bar)
    rep stosw
    mov al,0
    mov cl,40-mapSize   ; rest of screen is null
    rep stosw
    pop cx
    loop @B
    mov cl,40
    rep stosw           ; line of null at end of data
;generate mines
    mov di,mapData
    mov cl,mineCount
@@: in ax,40h
    mov bx,mapSize*40   ; size of map buffer in bytes (including nulls)
    xor dx,dx           ; clear DX for DIV
    div bx
    mov bx,dx           ; spot == rand()%total_spots
    shl bx,1            ; force even (word align) address
    mov dx,[di+bx]      ; load map spot
    cmp dl,20h
    jne @B              ; only write in empty space (20h)
    mov byte [di+bx],'*'
;place numbers on map around mines giving hints
    sub bx,82
    call packMineCount  ; NW, N, NE
    add bx,154
    call packMineCount  ; SW, S, SE
    sub bx,82
    call mineCounter    ; E
    sub bx,4
    call mineCounter    ; W
    loop @B
;setup video segment
    push 0B800h
    pop es
;draw board to screen
    xor di,di
    mov ax,7FEh         ; color + ascii char
    mov cl,mapSize
@@: push cx
    mov cl,mapSize
    rep stosw
    pop cx
    add di,80-(mapSize*2)   ; next line down
    loop @B
inputLoop:
    mov ax,3            ; read mouse info
    int 33h
    shr cx,2            ; horz. 0-80 -> 320/4 = 40 chars (80 bytes)
    shr dx,3            ; vert. 0-24 -> 200/8 = 25 chars high
    and bx,bx           ; test buttons
    jz inputLoop
;calc mouse click address
    mov ax,80
    mul dx              ; mul doubles as xor dx,dx later on
    add ax,cx           ; 80*y + x
    mov si,ax           ; si = video and map data offset
;click action
    call stackFill
    lods word [es:si]   ; (lodsw [es:si]) bytecode: db 26h, 0ADh
    cmp al,'*'
    jne @F
winLoose:           ; win or loose brings us here
    xor ax,ax
    int 16h
    ret             ; END OF GAME
; win game test.... if unclicked spaces == mineCount then you win
@@: xor si,si
    mov cx,mapSize*40
wincheck:
    lods word [es:si]   ; lodsw [es:si] (bytecode: db 26h,0ADh)
    cmp al,0FEh         ; still covered?
    jne @F
    inc dx          ; count unclicked spots
@@: loop wincheck
    cmp dl,mineCount    ; all mines accounted for?
    je winLoose
jmp inputLoop

;do horizontal row of three (above or below a mine)
packMineCount:          ; save some bytes
    push cx
    mov cl,3
@@: call mineCounter
    inc bx
    inc bx
    loop @B
    pop cx
ret

;incriment 1 of the 8 spaces around mine (assuming no other mine in it)
mineCounter:
    mov dx,[di+bx]
    and dl,dl           ; game board clipping
    jz @F
    cmp dl,'*'          ; dont change value of mines
    je mineCountDone
    cmp dl,20h
    jne @F
    mov dx,830h
@@: sub dx,0FEFFh
    mov [di+bx],dx      ; and store
mineCountDone:
ret

;4-way flood fill (not full 8 way)
stackFill:
    mov ax,[es:si]      ; load scr char
    cmp al,0FEh         ; don't fill if already revealed/flagged
    jne @F
    mov ax,[si+mapData] ; load map char
    mov [es:si],ax      ; copy to screen
    cmp al,20h          ; stop fill if close to a mine
    jne @F          ; if map char != empty space then ret
    lodsw           ; si+=2
    call stackFill      ; x+1
    add si,78
    call stackFill      ; y+1
    sub si,160
    call stackFill      ; y-1
    add si,78
    call stackFill      ; x-1
    lodsw           ; si+=2
@@: ret

heapPtr:            ; start of game map memory heap

;END OF PROGRAM