C/C++ Users Group Library 1996 July

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Assembly Source File | 1988-02-07 | 8.4 KB | 378 lines

page 60,132 ;-------------------------------------------------------------------------- ; e g a a . a s m ; --------------- ; Low-level driver for the ega device. ; ; update history ; -------------- ; Jun, 17. 1987 "dos.mac" and macro-usage added. ; ; Written by Rainer Gerhards ; Petronellastr. 6 ; D-5112 Baesweiler ; Phone (49) 2401 - 1601 ;-------------------------------------------------------------------------- include dos.mac if1 %out Info: EGA driver selected. endif LONG macro bed, ziel ; conditional jump > 127 byte local l1, l2 bed l1 jmp short l2 l1: jmp ziel l2: endm SETX MAX_X equ 640 ; maximum pixel x MAX_Y equ 350 ; maximum pixel y EXTERN vidbase,word,VID_BASE PSEG BEGIN setpixel ;** ; name setpixel ; ; synopsis setpixel(x, y, color); ; int x, y; coordinate of the pixel ; int color; pixel-color ; ; description This function sets a pixel of color "color" at ; the specified coordinate. ;** ENTERF push es mov ax, VID_BASE ; load base adr mov es, ax mov di, [bp]+X ; load x value mov bx, [bp]+X+2 ; load y value cmp di, MAX_X ; x range ok? jae sexit cmp bx, MAX_Y ; y range ok? jae sexit ; mov cx, bx shl bx, 1 ; 2 * shl bx, 1 ; 4 * add bx, cx ; 5 * shl bx, 1 ; 10 * shl bx, 1 ; 20 * shl bx, 1 ; 40 * shl bx, 1 ; 80 * = y-byteoffset mov cx, di rept 3 shr cx, 1 ; x / 8 = x-byteoffset endm add bx, cx ; total byteoffset ; mov cx, di ; load x value and cl, 07h ; x mod 8 xor cl, 07h ; shiftcount = 7 - x mod 8 mov ch, 1 ; mask shl ch, cl ; shift mask to position mov dx, 03ceh mov al, 05 out dx, al ; mode register inc dx mov al, 2 out dx, al ; write mode 2 dec dx mov al, 8 out dx, al ; bit mask register inc dx mov al, ch out dx, al ; store mask mov al, es:[bx] mov ax, [bp]+X+4 ; load color mov es:[bx], al ; write pixel mov dx, 03ceh mov al, 5 out dx, al ; mode register inc dx xor al, al out dx, al ; write mode 0 dec dx mov al, 8 out dx, al ; bit mask register inc dx mov al, 0ffh ; allow access to all bits out dx, al sexit: pop es ; done! LEAVEF ENDFUNC setpixel BEGIN setewm2 ;** ; name setwm2 ; ; synopsis setwm2() ; ; description The ega knows 4 different write modes. The write-pixel ; routine uses write mode 2. After changing the write ; mode, die default mode (0) must be restored. So the ; write pixel routine has first to change the write mode ; to 2, write the pixel and then restore write-mode 0. ; This is very slow, if you've to write a lot of pixel. ; This routine (and rsestdwm) allows the higer-level ; routine to set write mode 2 at the beginning of her ; processing, to call qsetpix (which assumes that mode 2 ; is set) to write the pixel and then restore the write- ; mode to the default by calling rsestdwm. Because ; qsetpix must'nt perform mode-switches, it is much ; faster than setpix. ; caution When using this method, the write mode isn't restored ; until the higher-level drawing procedure hasn't ; finished. If this procedure would be aborted, the BIOS ; will not restore the ega registers. So the video- ; output will destroyed (display only grabbage). To ; recover from this situation, just restore the original ; ega register contents. This can by done by a little ; program, calling only rsestdwm. ;** mov dx, 03ceh mov al, 05 out dx, al ; mode register inc dx mov al, 2 out dx, al ; write mode 2 ret ENDFUNC setewm2 BEGIN rsestdwm ;** ; name rsestdwm ; ; synopsis rsestdwm() ; ; description This routine restores the ega standard write mode. ; For a deteiled discussion see function setewm2. ;** mov dx, 03ceh mov al, 5 out dx, al ; mode register inc dx xor al, al out dx, al ; write mode 0 dec dx mov al, 8 out dx, al ; bit mask register inc dx mov al, 0ffh ; allow access to all bits out dx, al ret ENDFUNC rsestdwm BEGIN qsetpix ;** ; name qsetpix ; ; synopsis qsetpix(x, y, color); ; int x, y; coordinate of the pixel ; int color; pixel-color ; ; description This function sets a pixel of color "color" at ; the specified coordinate, switching no write modes. ; For a deteiled discussion see function setewm2. ;** ENTERF push es mov ax, VID_BASE ; load base adr mov es, ax mov di, [bp]+X ; load x value mov bx, [bp]+X+2 ; load y value cmp di, MAX_X ; x range ok? jae qsexit cmp bx, MAX_Y ; y range ok? jae qsexit ; mov cx, bx shl bx, 1 ; 2 * shl bx, 1 ; 4 * add bx, cx ; 5 * shl bx, 1 ; 10 * shl bx, 1 ; 20 * shl bx, 1 ; 40 * shl bx, 1 ; 80 * = y-byteoffset mov cx, di rept 3 shr cx, 1 ; x / 8 = x-byteoffset endm add bx, cx ; total byteoffset ; mov cx, di ; load x value and cl, 07h ; x mod 8 xor cl, 07h ; shiftcount = 7 - x mod 8 mov ch, 1 ; mask shl ch, cl ; shift mask to position mov dx, 03ceh mov al, 8 out dx, al ; bit mask register inc dx mov al, ch out dx, al ; store mask mov al, es:[bx] mov ax, [bp]+X+4 ; load color mov es:[bx], al ; write pixel qsexit: pop es ; done! LEAVEF ENDFUNC qsetpix readbit macro local endmac mov al, 4 out dx, al inc dx mov al, ah out dx, al mov al, es:[bx] shl cl, 1 and al, ch jz endmac or cl, 1 endmac: endm BEGIN qgetpix ;** ; name getpix ; ; synopsis color = qgetpix(x, y); ; int x, y; coordinate of the pixel ; int color; returned color of that pixel ; ; description This function reads ("gets") the color of a ; specified pixel. ;** ENTERF push es mov ax, VID_BASE ; load base adr mov es, ax mov di, [bp]+X ; load x value mov bx, [bp]+X+2 ; load y value cmp di, MAX_X ; x range ok? jl nxt jmp gexit nxt: cmp bx, MAX_Y ; y range ok? jl proces jmp gexit ; proces: mov cx, bx shl bx, 1 ; 2 * shl bx, 1 ; 4 * add bx, cx ; 5 * shl bx, 1 ; 10 * shl bx, 1 ; 20 * shl bx, 1 ; 40 * shl bx, 1 ; 80 * = y-byteoffset mov cx, di rept 3 shr cx, 1 ; x / 8 = x-byteoffset endm add bx, cx ; total byteoffset ; mov cx, di ; load x value and cl, 07h ; x mod 8 xor cl, 07h ; shiftcount = 7 - x mod 8 mov ch, 1 ; mask shl ch, cl ; shift mask to position mov ah, 3 mov dx, 03ceh ; rept 4 readbit dec dx dec ah endm ; and cx, 000fh mov ax, cx gexit: pop es ; done, retval in ax! LEAVEF ENDFUNC qgetpix BEGIN setbyte ;** ; name setbyte ; ; synopsis setbyte(x, y, color, pattern); ; int x; x-coordinate of the byte, only ; valid if multiple of 8 ; int y; y-coordinate of the byte, may have ; any y-value ; int color; pixel-color ; int gr_byte; graphics pattern to set ; ; description This function puts the graphics pattern contained ; in gr_byte into the adapter memory. Gr_byte must ; be a multiple of 8, all other values are invalid ; and will be rounded. Gr_byte is defined as con- ; secutive 8 pixles on the x-axis, which do all have ; the SAME color. ; ; warning This function is only available with the ega driver. ; There is a nearly identic function in the hercules ; driver, but It schould be treated as available ; internal to the grphics library only. If you have to ; use it, use conditional compilation, too. This ; function is only available when ; #ifdef EGAGRAF == true! ;** ENTERF push es mov ax, VID_BASE ; load base adr mov es, ax mov di, [bp]+X ; load x value mov bx, [bp]+X+2 ; load y value cmp di, MAX_X ; x range ok? jae sbexit cmp bx, MAX_Y ; y range ok? jae sbexit ; mov cx, bx shl bx, 1 ; 2 * shl bx, 1 ; 4 * add bx, cx ; 5 * shl bx, 1 ; 10 * shl bx, 1 ; 20 * shl bx, 1 ; 40 * shl bx, 1 ; 80 * = y-byteoffset mov cx, di rept 3 shr cx, 1 ; x / 8 = x-byteoffset endm add bx, cx ; total byteoffset ; mov dx, 03ceh mov al, 8 out dx, al ; bit mask register inc dx mov al, [bp]+X+6 ; bit pattern out dx, al ; store mask mov al, es:[bx] mov ax, [bp]+X+4 ; load color mov es: [bx], al ; write pixel sbexit: pop es ; done! LEAVEF ENDFUNC setbyte ENDPS end