****************************************************************************** * * * UD.asm - UpsideDown - A fun (and educational too!) Schwabie * * * * Programmed by Darrin Massena, Mantis Development. * * No Rights Reserved - Hey everybody, it's FREE! * * * * To make UD using the Aztec 'C' assembler: * * 1) as UD.asm * * 2) ln -o UD UD.o -lc32 * * * * To make UD using the MetaCompost assembler: * * 1) Rewrite first few lines to get a suitable index into the data hunk. * * 2) Fix other odd incompatibilities. * * 3) Wait forever for assembling. * * 4) Wait forever for linking. * * 5) Wonder why it doesn't run correctly. * * 6) Give up and go buy Aztec 'C'. * * 7) Use the Aztec instructions above. * * * * WARNING! Playing around with the copper-list like this is very much dis- * * couraged for SERIOUS programs, but hey, why :-| when you can :-) ? * * * * Revision history : * * ------------------ * * 06/20/87 (DWM) Just having some innocent fun. * * 06/21/87 (DWM) Aggg! It's out of control! RUN, RUN! * * * ****************************************************************************** include "exec/types.i" include "graphics/gfx.i" include "graphics/gfxbase.i" include "graphics/view.i" include "graphics/copper.i" DSEG SysBase equ 4 * =========================================================================== CSEG * Define these as public and they'll be pulled in from C32.lib. public _LVOOpenLibrary,_LVOCloseLibrary public _LVOOutput,_LVOWrite call MACRO ;macro to call system routines jsr _LVO\1(a6) ENDM * =========================================================================== public UD UD * Does anyone know a 'cleaner' way to set the initial A4 data pointer? * movea.l #dummyVar+32766,a4 ;special stuff to get my relative A4 dc.w %0010100001111100 ; <-- doing it the hard way dc.l dummyVar+32766 * If any initializations fail, we'll just abort (cleanly, of course.) lea.l szDOS,a1 moveq #0,d0 move.l SysBase,a6 call OpenLibrary ;open dos.library move.l d0,_DOSBase beq Quit ;failed! move.l d0,a6 call Output ;get output filehandle move.l d0,d1 ;d1 = out fh lea.l szCredit,a0 move.l a0,d2 ;d2 = szCredit moveq #-1,d3 99$ addq.l #1,d3 ;loop, counting sz len tst.b (a0)+ bne 99$ call Write ;take the blame lea.l szGfx,a1 moveq #0,d0 move.l SysBase,a6 call OpenLibrary ;open graphics.library move.l d0,_GfxBase beq Quit ;failed? How? * Will the REAL copper-list please stand up? move.l d0,a0 ;a0 = _GfxBase move.l gb_ActiView(a0),a0 ;a0 = _GfxBase->ActiView move.l v_ViewPort(a0),a1 ;save ptr to first ViewPort move.l v_LOFCprList(a0),a0 ;a0 = _GfxBase->ActiView->LOFCprList move.l crl_start(a0),a0 ;a0 = ptr to actual copper list in use * We now have _GfxBase->ActiView->LOFCprList->start (whew!) * Get a pointer to the first BitMap in the view move.l vp_RasInfo(a1),a1 move.l ri_BitMap(a1),a1 ;a1 = first BitMap move.w bm_BytesPerRow(a1),d1 ;d1 = # of bytes across screen's bm move.w bm_Rows(a1),d2 ;d2 = # of rows in screen's BitMap * Scan through the copper-list until we find the first BPLMOD initialization. 1$ move.l (a0)+,d0 swap d0 cmp.w #$0108,d0 ;move to BPLMOD1? bne 1$ ; no, loop until we found it * Change modulos to step BACK a couple of scanlines instead of forward. move.w d1,d0 ;# of bytes for one line across screen add.w d0,d0 ; * 2 (have to skip back 2 lines - neg.w d0 ; think about it) move.w d0,-2(a0) ;set BPLMOD1 back up 2 lines move.w d0,2(a0) ;set BPLMOD2 back up 2 lines subq.w #1,d2 ;bottom line = BytesPerRow * (Rows - 1) mulu d1,d2 ;d2 = bottom line * Since we're going backwards, we have to start at the bottom of each bit- * plane instead of at the top. move.w 6(a0),d0 ;first plane hi addr swap d0 move.w 10(a0),d0 ;first plane lo addr add.l d2,d0 ;drop to bottom line move.w d0,10(a0) ;put back hi swap d0 move.w d0,6(a0) ;put back lo move.w 14(a0),d0 ;second plane hi addr swap d0 move.w 18(a0),d0 ;second plane lo addr add.l d2,d0 ;drop to bottom line move.w d0,18(a0) ;put back hi swap d0 move.w d0,14(a0) ;put back lo * It's time to quit, close up shop and say good-night. Quit move.l SysBase,a6 move.l _DOSBase,d0 ;close the dos.library if open beq 1$ move.l d0,a1 call CloseLibrary 1$ move.l _GfxBase,d0 ;close the graphics.library if open beq 2$ ; oops, not open move.l d0,a1 call CloseLibrary 2$ rts ;bye! * =========================================================================== DSEG * These vars are derived using the Mantis naming conventions. A brief * summary follows: * * p - indicates a pointer * n - 'new' structure * win,scr,fh - abbreviations for window, screen and filehandle structures * co - color 0x0RGB data type * sz - null terminated string type * rg - range of values (array) * b,w,l - byte, word, long data types * * Quiz: What does prgpfhOpen stand for? * .selif nepO fo sretnioP eldnaHeliF fo eGnaR a ot retnioP a :rewsnA dummyVar ;dummy, used to create my A4 szGfx dc.b "graphics.library",0 szDOS dc.b "dos.library",0 szCredit dc.b "UD - UpsideDown",$a1 dc.b " - by Darrin Massena, Mantis Development",$0a dc.b "Press Left-Amiga-N or drag any screen to return to normal.",$0a,0 even _GfxBase dc.l 0 _DOSBase dc.l 0 * =========================================================================== END