C/C++ Users Group Library 1996 July

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Assembly Source File | 1988-03-28 | 10.3 KB | 381 lines

page 80,132 page ; ; Kent Cedola ; 2015 Meadow Lake Court ; Norfolk, Virginia 23518 ; dgroup group _data _data segment word public 'data' assume ds:dgroup public _gdcolor,_gdgseg _gdcolor db 0 _gdgseg dw 0A000h _data ends _text segment byte public 'code' assume cs:_text,ds:dgroup public _egacolor,_egaline,_egaplot,_egafillrect _egacolor proc near push bp mov bp,sp mov al,[bp+4] mov _gdcolor,al pop bp ret _egacolor endp _egaline proc near push bp mov bp,sp push si push di call ega_init mov cx,[bp+4] ; Load starting X coordinate (X1) mov bx,[bp+6] ; Load starting Y coordinate (Y1) cmp cx,[bp+8] ; Is X1 <= X2? jbe noxchg ; Yes, continue xchg [bp+8],cx ; No, then switch (X1,Y1) with (X2,Y2) xchg [bp+10],bx ; ... mov [bp+4],cx mov [bp+6],bx noxchg: call bit_addr mov ah,_gdcolor mov bx,[bp+8] ; Load ending X coordinate (X2) mov di,[bp+10] ; Load ending Y coordinate (Y2) sub bx,[bp+4] ; Compute Delta X := X2 - X1; sub di,[bp+6] ; Compute Delta Y := Y2 - Y1; push bp or di,di jns line01 neg di cmp di,bx ja lineoct7 jmp short lineoct8 line01: cmp di,bx ja lineoct2 lineoct1: mov cx,bx ; Count Down = DX mov bp,bx ; Error Register = -DX/2 shr bp,1 ; ... neg bp ; ... lineoct1L: out dx,al cmp byte ptr es:[si],0 mov es:[si],ah dec cx js linedone ror al,1 adc si,0 add bp,di js lineoct1L add si,80 sub bp,bx jmp short lineoct1L lineoct2: mov cx,di ; Count Down = DY mov bp,di ; Error Register = -DY/2 shr bp,1 ; ... neg bp ; ... lineoct2L: out dx,al cmp byte ptr es:[si],0 mov es:[si],ah dec cx js linedone add si,80 add bp,bx js lineoct2L ror al,1 adc si,0 sub bp,di jmp short lineoct2L lineoct7: mov cx,di ; Count Down = -DY mov bp,di ; Error Register = DY/2 shr bp,1 ; ... neg bp ; lineoct7L: out dx,al cmp byte ptr es:[si],0 mov es:[si],ah dec cx js linedone sub si,80 add bp,bx js lineoct7L ror al,1 adc si,0 sub bp,di jmp short lineoct7L lineoct8: mov cx,bx ; Count Down = DX mov bp,bx ; Error Register = -DX/2 shr bp,1 ; ... neg bp ; ... lineoct8L: out dx,al cmp byte ptr es:[si],0 mov es:[si],ah dec cx js linedone ror al,1 adc si,0 add bp,di js lineoct8L sub si,80 sub bp,bx jmp short lineoct8L linedone: pop bp call ega_term pop di pop si pop bp ret _egaline endp _egaplot proc near push bp mov bp,sp push si push di call ega_init mov cx,[bp+4] mov bx,[bp+6] call bit_addr out dx,al ; Set mask byte to change only our bit mov al,es:[si] mov al,_gdcolor mov es:[si],al ; Apply merge function to bit and store call ega_term pop di pop si pop bp ret _egaplot endp _egafillrect proc near push bp mov bp,sp push si push di call ega_init mov ax,[bp+4] ; Load X1 coordinate of current frame mov bx,[bp+6] ; Load Y1 coordinate of current frame mov di,[bp+8] ; Load X2 coordinate of current frame mov si,[bp+10] ; Load Y2 coordinate cmp ax,di jbe fill01 xchg ax,di fill01: cmp bx,si jbe fill02 xchg bx,si fill02: MOV cx,ax ; Determine the first mask byte AND cl,7 ; ... mov dl,0FFh shr dl,cl mov [bp+4],dl MOV cx,DI ; Determine the second (last) mask byte AND cl,7 ; ... mov dl,080h sar dl,cl mov [bp+6],dl mov cx,si ; Load Y2 corrdinate of current frame MOV DX,AX ; Determine width in bytes SHR DX,1 ; Convert X1 to a byte count SHR DX,1 ; ... SHR DX,1 ; ... SHR DI,1 ; Convert X2 to a byte count SHR DI,1 ; ... SHR DI,1 ; ... SUB DI,DX ; Width + 1 JNZ clear01 PUSH AX MOV AL,[bp+6] AND AL,[bp+4] MOV [bp+8],AL POP AX clear01: DEC DI ; Width SUB CX,BX ; Determine the Height of the frame INC CX ; ... MOV SI,AX ; SHR SI,1 ; Divide X corrdinate by eight and SHR SI,1 ; ... SHR SI,1 ; ... mov ax,bx shl ax,1 shl ax,1 add ax,bx add ax,0A000h mov es,ax ; CX Height ; SI Byte Offset ; DI Width ; ES 'A000' mov dx,03CEh mov al,8 out dx,al inc dx MOV AH,_gdcolor MOV AL,[bp+4] OUT DX,AL CALL col_fill OR DI,DI JS L3 JZ L2 MOV AL,0FFh OUT DX,AL L6: CALL col_fill DEC DI JNZ L6 L2: MOV AL,[bp+6] OUT DX,AL CALL col_fill L3: jmp short done ; AH Color ; CX Height ; DX '03CF' ; SI Byte Offset ; ES 'A000' col_fill: PUSH CX PUSH SI col_f01: MOV AL,ES:[SI] MOV ES:[SI],AH ADD SI,80 LOOP col_f01 POP SI POP CX INC SI RET done: call ega_term pop di pop si pop bp ret _egafillrect endp ega_init proc near mov dx,03CEh ; Load address of EGA graphic controller mov al,_gdcolor ; Load current color setting or al,al ; Is the merge (xor) bit set? jns nomerge ; No, jump over merge code mov ax,01803h ; Yes, load xor merge setting out dx,ax ; Set the EGA hardware register nomerge: mov ax,00205h ; Load parameters for write mode #2 out dx,ax ; Set the graphic controller write mode mov al,08h ; out dx,al ; inc dx ; mov es,_gdgseg ret ega_init endp ega_term proc near mov dx,03CEh mov ax,00003h out dx,ax mov al,005h out dx,ax mov ax,0FF08h out dx,ax ret ega_term endp ; CX,BX (X,Y) bit_addr proc near mov si,bx ; Compute SI = Y * 80 for row offset shl si,1 ; ... (SI = Y * 2) shl si,1 ; ... (SI = Y * 4) add si,bx ; ... (SI = Y * 5) shl si,1 ; ... (SI = Y * 10) shl si,1 ; ... (SI = Y * 20) shl si,1 ; ... (SI = Y * 40) shl si,1 ; ... (SI = Y * 80) mov bx,cx ; Compute BX = X / 8 for column offset shr bx,1 ; ... (BX = X / 2) shr bx,1 ; ... (BX = X / 4) shr bx,1 ; ... (BX = X / 8) add si,bx ; Compute BX = BX + SI, first byte and cl,7 ; Compute AL = starting bit mask mov al,080h ; ... load default of bit 0 ror al,cl ; ... rotate to the starting bit mask ret bit_addr endp _text ends end