; ************************************************************************** ; This is the source of DESKTOP.PRG, a program that changes the normal gray ; background with a Degas PI3 file. This source is public domain, but I ; would appreciate it very much if a program that uses (part) of this ; source respects the name of the author! ; ************************************************************************** ; This specific version (1.1) returns the picture adress in intout[2] ; when vs_clip() is called. "N_DP" is returned in intout[0] to ; be able to check whether this adress is valid. ; ************************************************************************** ; Noud van Kruysbergen ; N.I.C.I. ; P.O. Box 9104 ; 6500 HE Nijmegen ; The Netherlands ; email: kruysbergen@hnykun53.bitnet ; ************************************************************************** text move.l 4(A7),A0 ; these lines are the normal move.l #$100,D4 ; ones for a TSR program add.l 12(A0),D4 ; there's nothing interesting add.l 20(A0),D4 ; here. add.l 28(A0),D4 ; You only have to add 32000 bytes add.l #32000,D4 ; for the (PI3) picture. lea noudtext,A0 ; show the copyright lines bsr cconws ; to the screen clr.w -(A7) ; try to open the file pea file1 ; "DESKTOP.PI3" in the AUTO move.w #$3d,-(A7) ; folder. trap #1 ; D3 = Fopen("AUTO\DESKTOP.PI3",0); addq.l #8,A7 move.w D0,D3 bpl ok1 ; File exists: goto ok1 clr.w -(A7) ; If the file does not exist: pea file2 ; try to open "DESKTOP.PI3" in the move.w #$3d,-(A7) ; root directory. trap #1 ; D3 = Fopen("DESKTOP.PI3",0); addq.l #8,A7 move.w D0,D3 bpl ok1 ; File exist: goto ok1 lea error1,A0 ; No "DESKTOP.PI3" exists bsr cconws ; print this to screen move.w #7,-(A7) ; let the bell ring move.w #2,-(A7) trap #1 ; Cconout(7); addq.l #4,A7 bsr wait ; wait for a moment to be able to clr.w -(A7) ; read the message and trap #1 ; Pterm0(); ok1: clr.w -(A7) ; The file exists. Skip the move.w D3,-(A7) ; PI3 header info (34 bytes). move.l #34,-(A7) move.w #$42,-(A7) trap #1 ; Fseek(34L,D3,0); adda.l #10,A7 pea picbuffer ; Read the picture in the move.l #32000,-(A7) ; buffer (which begins at move.w D3,-(A7) ; 'picbuffer'. move.w #$3f,-(A7) trap #1 ; Fread(D3,32000L,picbuffer); adda.l #12,A7 cmpi.l #32000,D0 ; 32000 bytes read? beq ok2 ; goto ok2 lea error2,A0 ; else print warning to screen bsr cconws bsr wait ; wait, but do install! ok2: pea gemnew ; the new gem vector move.w #34,-(A7) move.w #5,-(A7) trap #13 ; gemold=Setexc(34,gemnew); addq.l #8,A7 move.l D0,gemold lea gemnew,A0 move.l D0,-4(A0) ; return adress for XBRA protocol move.w D3,-(A7) ; close the file move.w #$3e,-(A7) trap #1 ; Fclose(D3); addq.l #4,A7 clr.w -(A7) ; terminate and stay resident move.l D4,-(A7) ; with no errorcode move.w #$31,-(A7) trap #1 ; Pterm(D4,0); ; -------------------------------------------------------------------------- cconws: move.l A0,-(A7) ; routine to print line to screen move.w #9,-(A7) trap #1 ; Cconws(A0); addq.l #6,A7 rts wait: move.w #1000,D1 ; routine that eats up CPU time wait1: move.w #1000,D0 ; simply to wait wait2: dbf D0,wait2 dbf D1,wait1 rts ; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ; this is where it all is about. The new gemvector starts here. ; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ dc.b "XBRAN_DP" dc.l 0 gemnew: cmpi.w #115,D0 ; test whether it is a VDI call bne gemquit ; ************************************************************************* ; It is a VDI call! movem.l D0-A3,-(A7) ; save registers move.l D1,A0 move.l (A0),A0 ; D0 = control[0]; move.w (A0),D0 ; what VDI call is it? ; ************************************************************************** ; Is the VDI call vr_recfl()? cmpi.w #114,D0 bne nofill cmpi.w #2,interior ; Has vsf_interior(handle,2); bne gemrest ; been called? cmpi.w #4,style ; Has vsf_style(handle,4); bne gemrest ; been called? tst.w mode ; Is it in the clipping mode? beq gemrest move.l D1,A0 move.l 8(A0),A0 ; D0 = intin[0] etc.. move.w (A0)+,D0 ; x0==0 bne gemrest move.w (A0)+,D0 ; y0==0 || y0==19 cmpi.w #19,D0 beq menu tst.w D0 bne gemrest menu: move.w (A0)+,D0 ; x1==639 cmpi.w #639,D0 bne gemrest move.w (A0),D0 ; y1==399 cmpi.w #399,D0 bne gemrest ; All the conditions are true. They mean that a gray background should ; be drawn. The exact size is set in the clipping variables. They are ; used to draw the background. move.l $44e,A1 ; A1 = *(long *)0x44e; move.w clipy0,D0 move.w D0,D2 ; D0 = D2 = clipy0; muls #80,D0 ; D0 *= 80 /* 80 characters per line */ adda.l D0,A1 ; A1 = screenadres + clipy0 offset; lea picbuffer,A0 ; A0 = pictureadres; adda.l D0,A0 ; A0 = pictureadres + clipy0 offset; move.w clipy1,D0 ; D0 = clipy1; sub.w D2,D0 ; D0 = clipy1 - clipy0; move.w D0,D2 ; D2 = total number of lines; move clipx0,D3 ; D3 = x0; move.w D3,D7 ext.l D7 divs #8,D7 move.w D7,D3 adda.l D3,A0 adda.l D3,A1 ; D3 = clipx0/8; swap D7 move.w D7,D4 ; D4 = clipx0%8; move.w clipx1,D5 addq.w #1,D5 move.w D5,D7 ext.l D7 divs #8,D7 move.w D7,D5 ; D5 = clipx1/8; swap D7 move.w D7,D6 ; D6 = clipx1%8; move.l D5,D0 sub.l D3,D0 bne label3 ; if (D3>D5) goto label3; ; -------------------------------------------------------------------------- ; This routine takes care of the times when the desktop has to be redrawn ; within one character (for instance from bit 2 to bit 5). ; -------------------------------------------------------------------------- move.w D6,D7 ; D7 = D6; /* D6=5+1 */ subi.w #8,D7 neg.w D7 ; D7 = -(D6-8); /* D7=2 */ move.b #-1,D3 ; D3 = 11111111 /* in binary mode */ lsr.b D7,D3 ; D3 = 00111111 lsl.b D7,D3 ; D3 = 11111100 lsl.b D4,D3 ; D3 = 11110000 /* D4=2 */ lsr.b D4,D3 ; D3 = 00111100 ; This is a very elegant way to make a byte that has the bits set that ; should contain the background information. A zero in this byte means that ; what is on screen at that location should stay there. In this case only ; the bits 5,4,3 and 2 (numbers 2,3,4 and 5 from the left) have to be updated. byteloop: move.b D3,D0 ; D0 = 00111100 move.b (A0),D7 ; D7 = picturebyte and.b D0,D7 ; D7 &= 00111100 not.b D0 ; D0 = 11000011 and.b (A1),D0 ; screenbyte &= 11000011 add.b D0,D7 ; D7 = picturebyte + screenbyte move.b D7,(A1) ; screenbyte = D7 adda.l #80,A0 ; next pictureline adda.l #80,A1 ; next screenline dbf D2,byteloop ; do this for all # lines bra selfok ; quit the GEM call ; -------------------------------------------------------------------------- ; More than one byte have to be redrawn. ; -------------------------------------------------------------------------- label3: subq.w #1,D0 ; # bytes -= 1 for 'dbf' sake. tst.w D4 ; xclip0 on a byte-boundairy? seq D5 ; yes : set D5 beq yloop ; : goto yloop tst.w D0 ; D0==0? /* only 1 byte? */ sne D5 ; no : set D5 beq yloop ; yes : goto yloop subq.w #1,D0 ; more than one byte: D0 -= 1; ; -------------------------------------------------------------------------- ; Start of the actual updating routine. ; -------------------------------------------------------------------------- ; We first have to draw the remainder of the first byte. If there is no ; remainder (D4=0) we don't have to do this. Suppose we have to redraw ; from bit 4 (from the left, so actually bit 5): D4=3. yloop: move.l A0,A2 ; A2 = pictureadres move.l A1,A3 ; A3 = screenadres tst.w D4 ; if no remainder has to be drawn beq nostart ; then don't do this move.b (A2)+,D3 ; D3 = picturebyte move.b #-1,D7 ; D7 = 11111111 lsr.b D4,D7 ; D7 = 00011111 and.b D7,D3 ; D3 &= 00011111 /* picturebits */ not.b D7 ; D7 = 11100000 and.b (A3),D7 ; D7 &= screenbyte /* screenbits */ add.b D3,D7 ; D7 += D3 /* picture+screen */ ; D7 contains the high bits from the old background and the low bits from ; the redrawn background. move.b D7,(A3)+ ; screenbyte = D7 ; When we arrived here, we are at a byte boundary. We are going to copy ; bytes from the picture to the screen if necessary (D5 was set) nostart: move.w D0,D7 ; D7 = # bytes tst.w D5 beq endbyte ; D5 not set: goto endbyte xloop: move.b (A2)+,(A3)+ ; screenbyte = picturebyte dbf D7,xloop ; do this # bytes times ; We still are at a byte boundary. Are there any bits to draw any further? endbyte: tst.w D6 beq no_end ; If not, skip this part. D6 contains the number of bits to update, say 3. move.b (A2)+,D3 ; D3 = picturebyte move.b #-1,D7 ; D7 = 11111111 lsr.b D6,D7 ; D7 = 00011111 not.b D7 ; D7 = 11100000 and.b D7,D3 ; D3 &= 11100000 /* picturebits */ not.b D7 ; D7 = 00011111 and.b (A3),D7 ; D7 &= screenbyte add.b D3,D7 ; D7 = screenbits + picturebits move.b D7,(A3) ; screenbyte = D7 no_end: adda.l #80,A0 ; next picture line adda.l #80,A1 ; next screen line label1: dbf D2,yloop ; do this # lines times selfok: movem.l (A7)+,D0-A3 ; quit the GEM call rte ; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ; This is were the redrawing of the background ends. It all is in fact ; nothing more than shifting a proper amount of bits at a proper time! ; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ; ************************************************************************** ; Is the VDI call vst_interior()? nofill: move.l D1,A0 move.l 4(A0),A0 move.w (A0),D2 ; D2 = intin[0]; cmpi.w #23,D0 bne nointerior move.w D2,interior ; interior = intin[0]; bra gemrest ; ************************************************************************** ; Is the VDI call vst_style()? nointerior:cmpi.w #24,D0 bne nostyle move.w D2,style ; style = intin[0]; bra gemrest ; ************************************************************************** ; Is the VDI call vs_clip()? nostyle: cmpi.w #129,D0 bne gemrest move.w D2,mode ; mode = intin[0]; beq gemrest ; if (mode==0) no clipping; cmpi.w #-1,D2 bne normal ; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ ; for version 1.0 exclude the part between the ...++++++... lines !!! ; ; We return the picture adress in intout[2] when vs_clip(x,-1,x) is called. ; This is an illegal not documented feature! When DESKTOP.PRG is not ; installed the content of intout[2] is NOT the picture adress! ; This can be controlled by intout[0]: if *(long *)intout==$4e5f4450 ; ("N_DP") the value *(long *)(intout+4) is a valid picture adress. move.l D1,A0 move.l 12(A0),A0 move.l #$4e5f4450,(A0)+ ; *(ong *)intout=0x4e5f4450 clr.l (A0)+ lea picbuffer,A1 move.l A1,(A0) ; *(long *)(intout+4)=picbuffer; bra selfok ; This is the normal clipping procedure ; ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ normal: move.l D1,A0 move.l 8(A0),A0 move.w (A0)+,clipx0 ; clipx0 = intin[0]; move.w (A0)+,clipy0 ; clipy0 = intin[1]; move.w (A0)+,clipx1 ; clipx1 = intin[2]; move.w (A0),clipy1 ; clipy1 = intin[3]; gemrest: movem.l (A7)+,D0-A3 ; restore registers gemquit: move.l gemold,-(A7) ; put old GEM vector on the stack rts ; and jump to it... data noudtext: dc.b 27,'E',13,10,10," ",27,'p'," Desktop Picture V1.1 " dc.b 27,'q',13,10," ",27,'p'," Noud van Kruysbergen ",27,'q',13,10,10,0 error1: dc.b " **** Error: DESKTOP.PI3 ? ****",13,10,0 error2: dc.b " Warning: DESKTOP.PI3 < 32034",13,10,0 file1: dc.b "AUTO\DESKTOP.PI3",0 file2: dc.b "DESKTOP.PI3",0 even bss style: ds.w 1 interior: ds.w 1 mode: ds.w 1 clipx0: ds.w 1 clipy0: ds.w 1 clipx1: ds.w 1 clipy1: ds.w 1 gemold: ds.l 1 picbuffer:ds.l 1 ; 32000 bytes are reserved from here. end