PsL Monthly 1994 January

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Assembly Source File | 1990-01-16 | 10.0 KB | 401 lines

;------------------------------------------------------------------------- ; MERLIN.ASM ; ; 1/15/90 ; ; David Stafford ; CIS 72411,2670 or 76666,2542 ; ; This is heavily hacked code. Don't take it too seriously. ; ; See MERLIN.DOC for usage instructions. ; Assembled with Turbo Assembler. ;------------------------------------------------------------------------- locals code segment para public 'code' assume cs:code,ds:code,es:code,ss:code org 100h ;------------------------------------------------------------------------- ;Store the board at PSP:80h (command line) ;------------------------------------------------------------------------- Board equ 80h ;------------------------------------------------------------------------- ;Window details ;------------------------------------------------------------------------- COrgX equ 1 ;client X origin COrgY equ 1 ;client Y origin PaneWidth equ 6 ;window pane width PaneHeight equ 3 ;window pane height CWidth equ PaneWidth*3+2 ;client window width CHeight equ PaneHeight*3+2 ;client window height FOrgX equ COrgX-1 ;frame X origin FOrgY equ COrgY-1 ;frame Y origin FWidth equ CWidth+2 ;frame window width FHeight equ CHeight+2 ;frame window height ;------------------------------------------------------------------------- ;.COM entry point ; ;Ordinarily I put these things at the end of the program (so they don't ;hang around resident) but this one is small. ;------------------------------------------------------------------------- Init proc near call Scramble mov ax,3509h ;get interrupt vector 9 int 21h ;(keyboard interrupt) mov word ptr OldInt9,bx mov word ptr OldInt9+2,es mov ax,2509h ;set interrupt vector 9 mov dx,offset TSRMain int 21h mov dx,offset ResidentEnd int 27h ;terminate and stay resident endp ;------------------------------------------------------------------------- ;Draws the bars in the box frame. ; ;Calls DrawLine (in a manner of speaking) twice and falls through. ;------------------------------------------------------------------------- DrawBars proc near mov bx,0b3b3h mov dl,0b3h mov ax,offset DrawLine ;execute DrawLine 3 times push ax push ax endp ;fall through ;------------------------------------------------------------------------- ;Draws a single line. ; ;in: bl = left char, bh = right char, dl = intersection char ; es:di points into video ;------------------------------------------------------------------------- DrawLine proc near mov ah,0fh ;color attribute mov al,bl stosw mov cl,CWidth mov al,0c4h ;horizontal single line rep stosw mov es:[di-(PaneWidth+1)*2],dl mov es:[di-(PaneWidth+1)*4],dl mov al,bh stosw add di,160-FWidth*2 ;point to next line in video ret endp ;------------------------------------------------------------------------- ;Int 9 (keyboard interrupt) entry point ;This routine is modified by Accept, Restore and Init so be careful! ;------------------------------------------------------------------------- TSRMain proc near sti push ax in al,60h ;get scan code from keyboard cmp al,50 ;check for 'm' key jne @@Exit ;no, then exit mov ah,2 ;check shift keys int 16h and al,0fh cmp al,4 ;check CTRL key je Accept ;OK, popup @@Exit: pop ax cli @@ByeByte: db 0eah ;intersegment far jump OldInt9 dd ? ;chain to previous int 9 handler endp ;----------------------------------------------------------------------------- ;Gets here when the hotkey has been accepted. ;Modifies TSRMain. ;----------------------------------------------------------------------------- Accept proc near cld push bx push cx push dx push si push di push ds push es push cs ;ds = cs pop ds push cs ;es = cs pop es ;Here I install a short jmp to @@ByeBye in TSRMain mov word ptr TSRMain,12ebh endp ;fall through ;----------------------------------------------------------------------------- ;Resets the keyboard and signals end-of-interrupt to the 8259 ;----------------------------------------------------------------------------- ResetKeyboard proc near in al,61h ;get current control port value push ax ;save it or al,80h ;set bit 7 out 61h,al ;send reset value pop ax ;restore control port value out 61h,al ;enable keyboard cli mov ax,0f20h ;al = get EOI value ;ah = get video mode (below) out 20h,al ;send EOI to 8259 sti endp ;fall through ;----------------------------------------------------------------------------- ;Gets the video mode and saves the video buffers ; ;The strange looking segment address (0b03fh) for the video screen lets ;me assume an offset of zero for some accesses (saves a couple bytes). ;----------------------------------------------------------------------------- GetVideo proc near int 10h ;get the video mode (assume ah = 0fh) ;bh = video page mov dx,0b03fh ;assume mono cmp al,7 ;is it mono? je @@GotSegment cmp al,2 ;color? je @@GetPage cmp al,3 ;color? jne BadVideo ;bad video mode, don't pop up! @@GetPage: mov dh,0b8h ;set for color add dh,bh ;add the page @@GotSegment: mov ds,dx ;get video segment mov ah,3 ;bh = video page int 10h ;get cursor shape & position push cx ;save cursor shape mov ch,20h mov ah,1 ;hide cursor int 10h ;set cursor shape xor si,si ;offset into video screen mov di,offset VideoBuf mov bx,FHeight ;bx = loop variable @@NextLine: mov cx,FWidth rep movsw add si,160-FWidth*2 ;point to next line in video dec bx jnz @@NextLine push ds ;es = ds (video page) pop es push cs ;ds = cs pop ds endp ;fall through ;----------------------------------------------------------------------------- ;Draws the box frame ;----------------------------------------------------------------------------- DrawFrame proc near xor di,di ;offset into video screen mov bx,0bfdah mov dx,03c2h ;dh is loop counter jmp short @@Doit @@Top: mov bx,0b4c3h mov dl,0c5h @@DoIt: call DrawLine call DrawBars dec dh jnz @@Top mov bx,0d9c0h mov dl,0c1h call DrawLine jmp short DrawClient endp ;------------------------------------------------------------------------- ;Restores the video buffer ;Modifies TSRMain. ;------------------------------------------------------------------------- Restore proc near xor di,di ;offset into video screen mov si,offset VideoBuf mov bl,FHeight ;bx = counter, assume bh = 0 @@NextLine: mov cl,FWidth ;assume ch = 0 rep movsw add di,160-FWidth*2 ;point to next line in video dec bx jnz @@NextLine mov ah,1 pop cx ;restore cursor shape int 10h ;Arrive here if in graphics mode. ;Uninstall the short jmp to @@ByeBye in TSRMain. BadVideo: mov word ptr TSRMain,050fbh pop es ;exit pop ds pop di pop si pop dx pop cx pop bx pop ax iret endp ;------------------------------------------------------------------------- ;Scrambles the game board ;------------------------------------------------------------------------- Scramble proc near push ds mov ds,dx ;assume dx = 0 mov ax,ds:[46ch] ;get timer (random number) pop ds mov bl,Board+1 ;assume bh = 0 mov cl,9 ;loop counter (assume ch = 0) @@Top: xor dl,dl shr ax,1 adc dl,dl mov [bx],dl inc bx loop @@Top ret endp ;------------------------------------------------------------------------- ;Jump here when you want to scramble the board and return to DrawClient ;------------------------------------------------------------------------- ScrambleKey proc near call Scramble endp ;fall through ;----------------------------------------------------------------------------- ;Draws the individual squares ;----------------------------------------------------------------------------- DrawClient proc near mov dx,Board+1 ;damn, can't assume dh = 0 mov di,(CHeight*80+COrgX)*2 ;offset into video screen mov cl,3 @@Top: push cx mov bl,3 @@Top1: mov si,dx mov bh,3 @@Top2: mov ax,7020h ;char/attribute mov cl,[si] jcxz @@0 ;assume ch = 0 cbw ;ah = 0 @@0: mov cl,6 rep stosw inc si ;next square inc di ;skip video column inc di dec bh jnz @@Top2 sub di,160+CWidth*2+2 ;move up a row dec bx ;assume bh = 0 jnz @@Top1 sub di,160 mov dx,si pop cx loop @@Top endp ;fall through ;----------------------------------------------------------------------------- ;Gets a keypress and performs the desired action ;----------------------------------------------------------------------------- GetKey proc near cbw ;assume al < 128 cwd ;dx = 0 int 16h ;get keypress cmp al,27 ;escape? je Restore cmp al,13 je ScrambleKey sub al,'0' cmp al,9 ja GetKey mov dl,al mov bx,offset Keys-1 xlat mov bx,Board+1 mov cl,9 @@ToggleLoop: dec dx ;assume dh = 0 jz @@Toggle shr al,1 jnc @@Bottom @@Toggle: xor byte ptr [bx],1 @@Bottom: inc bx loop @@ToggleLoop jmp short DrawClient endp ;------------------------------------------------------------------------- ;Data ;------------------------------------------------------------------------- ;Bitmaps for which keys affect which squares. Only 8 bits for each ;square because we assume key X toggles square X. Otherwise we would ;have to use 9 more bytes for this table and the added logic is less ;than 9 bytes. Keys db 00001101b ;1 db 00000011b ;2 db 00011010b ;3 db 00100001b ;4 db 01011010b ;5 db 10000100b ;6 db 01011000b ;7 db 11000000b ;8 db 10110000b ;9 ;Video save area VideoBuf label byte ;screen save area ResidentEnd equ offset VideoBuf + FWidth * FHeight * 2 ends end Init