* *** xtext.asm ************************************************************* * * XText -- The XText Routine * (from the FastText algorithms created in January, 1986) * from Book 1 of the Amiga Programmers' Suite by RJ Mical * * Copyright (C) 1986, 1987, Robert J. Mical * All Rights Reserved. * * Created for Amiga developers. * Any or all of this code can be used in any program as long as this * entire copyright notice is retained, ok? Thanks. * * HISTORY Name Description * ------------ --------------- ------------------------------------------- * 27 Oct 86 RJ Mical >:-{)* Translated this file. * * *************************************************************************** INCLUDE "xtext.i" IFND AZTEC ; If AZTEC not defined, do it the standard way XDEF _XText XREF _custom XREF _GfxBase ENDC IFD AZTEC ; If AZTEC defined, do it the non-standard way (sigh) PUBLIC _XText PUBLIC _custom PUBLIC _GfxBase ENDC _XText: * *************************************************************************** * These FastText algorithms were created by =Robert J. Mical= in January 1986 * Copyright (C) 1986, =Robert J. Mical= * All Rights Reserved * * This is my brute-force XText() routine. * It presumes many things about text: that the characters come in * pairs, that the characters are 8-bits wide (this one is not easily * undone), and more. * * The theory of operation here is that I will build a single plane of * normal characters (character data bits set, background bits clear) * in the Normal Text Plane, using the data from the Output Characters * Buffer. As needed, I will invert this plane (character bits clear, * background bits set) into the Inverted Text Plane. There's two other * globally accessible (pre-initialized) planes used: an AllClearPlane plane * of all bits clear, and an AllSetPlane plane of all bits set. * * Using these four planes, I can construct a bitmap of all possible pen * settings for the foreground and background. If corresponding bits * in the FgPen and BgPen are: * ----- ----- * 0 0 Use All Clear Plane * 0 1 Use Inverted Text Plane * 1 0 Use Normal Text Plane * 1 1 Use All Set Plane * * Note that if FgPen and BgPen are equal, I don't have to bother * constructing the Normal or Inverted Text Planes, since they'll * never be used. * * An optimization that evolves out of this fact is that you can fill a line * or part of a line of your text with spaces (blank characters) much more * quickly by setting the foreground pen equal to the background pen. The * trick with this optimization is to not spend too much time detecting * whether or not an area of text is all blank, for you may lose the * increased performance during the handling of normal text lines. * * A further optimization is that I'm guessing that many text calls * will not require the inverted plane, so I won't make it until I * discover that I need it. If programmers follow the * Intuition-encouraged standard of pen 1 for foreground and pen 0 * for background, then the bits are: FgPen -- 00001 * BgPen -- 00000 * In fact, if the text is *any* color against a background of zero, * this optimization works. * * For example, the plain PC monochrome text turns out to be pen 1 on * pen 0. No need to invert here! * * So I won't bother constructing the inverted plane until I discover * that it's needed. The cost of this is that I have to check a flag * once per time that I find an inverted bit plane is called for (6 times * maximum (though of course Dale would say 8 times maximum)), and the * savings is avoiding an unnecessary inversion. * * Note that this routine works with character pairs while building the * buffer. If you specify an odd number of characters, this routine will * round up the character count to the next higher even number, and then * build the buffer with that many characters. However, only the number * of characters you specify will actually be printed to the screen. * * ON ENTRY (on stack): * ARG0 = address of the XTextSupport structure * ARG1 = address of the text string * ARG2 = character count * ARG3 = x position for text output * ARG4 = y position for text output DREGS EQU 0 ; Offset to the pushed D-Registers DREGCOUNT EQU 6 ; How many D-Registers were pushed AREGS EQU (DREGS+(DREGCOUNT*4)) ; Offset to the pushed A-Registers AREGCOUNT EQU 5 FRONTPEN EQU (AREGS+(AREGCOUNT*4)) ; Local variable BACKPEN EQU (FRONTPEN+2) ; Local variable DRAWMODE EQU (BACKPEN+2) ; Local variable XBLTSIZE EQU (DRAWMODE+2) RETADDR EQU (XBLTSIZE+2) ; Our return address ARG0 EQU (RETADDR+4) ; Offset to passed arguments ARG1 EQU (ARG0+4) ARG2 EQU (ARG1+4) ARG3 EQU (ARG2+4) ARG4 EQU (ARG3+4) LEA -8(SP),SP ; Reserve memory for local variables MOVEM.L A2-A6/D2-D7,-(SP) MOVE.L ARG0(SP),A2 ; Get the XTextSupport structure address MOVE.L #_custom,A5 ; Get the address of the custom chip MOVE.L _GfxBase,A6 ; Load up A6 for graphics calls * Check the character count. * If it's zero, then split as there's nothing to do. * If it's less than zero, this is the signal that the programmer * wants *us* to figure out how long the string is. Nice touch, eh? * If it's greater than zero, then presume it's valid. MOVE.W ARG2+2(SP),D2 ; Get the character count BEQ RETURN ; and split if there's none to do BGT GOT_TEXT_COUNT ; If greater than zero, then it's real MOVE.L ARG1(SP),A4 ; Address of text string MOVEQ.L #-1,D2 ; Start with less than no characters 10$ ADDQ.W #1,D2 ; Increment character count TST.B (A4)+ ; Test if next is end of text BNE 10$ ; Branch if not MOVE.W D2,ARG2+2(SP) ; Save as character count GOT_TEXT_COUNT: * The result of the following 3 instructions is created by the 2 below * I include this commentary to keep things from getting confusing * ADDQ #1,D2 ; to round up * LSR.B #1,D2 ; Turn the char count into a pair count * SUBQ.W #1,D2 ; (-1 for DBRA of PAIRLOOP below) SUBQ.B #1,D2 LSR.B #1,D2 CALLSYS OwnBlitter ; Get that blitter * Get local copies of the pens, jazzed around to take the DrawMode into * account. Namely, if JAM1 then the background pen is automatically zero, * and if the INVERSVID flag is set then swap the foreground/background pens CLEAR D3 ; Save them as words MOVE.B xt_FrontPen(A2),D3 ; Load up the local front pen CLEAR D4 ; Start out presuming that back is zero MOVE.B xt_DrawMode(A2),D5 ; Test the draw mode MOVE.B D5,D6 ; Save a copy ANDI.W #3,D5 ; Strip off INVERSVID (and any other) bit MOVE.W D5,DRAWMODE(SP) ; and save the true drawmode CMP.B #RP_JAM1,D5 ; Is it JAM1? BEQ 1$ ; If it's JAM1, leave the local back as zero MOVE.B xt_BackPen(A2),D4 ; else load up the local back pen 1$ ANDI.B #RP_INVERSVID,D6 ; Was INVERSVID bit set? BEQ 2$ ; and skip if not EXG D3,D4 ; else exchange the pen registers 2$ MOVE.W D3,FRONTPEN(SP) ; Save the local front pen MOVE.W D4,BACKPEN(SP) ; Save the local back pen MOVE.W xt_CharHeight(A2),D6 ; Build the bltsize word LSL.W #6,D6 ; Height is shifted over as blitter likes it MOVE.W D6,XBLTSIZE(SP) ; Save this partial for later CMP.W D3,D4 ; Are the pens equal? BEQ PLANESET ; If so, skip building the planes * Wait 'til any blitting is done, and then initialize * the blitter for my personal use ... CALLSYS WaitBlit ; and wait for that baby to be free! CLEAR D3 MOVE.W D3,bltamod(A5) ; Set up the SRCA and SRCB modulos MOVE.W D3,bltbmod(A5) SUBI.W #1,D3 MOVE.W D3,bltafwm(A5) ; Masks are all set MOVE.W D3,bltalwm(A5) CLEAR D3 MOVE.B xt_MaxTextWidth(A2),D3 SUBQ.W #2,D3 MOVE.W D3,bltdmod(A5) MOVE.W #$0DFC,bltcon0(A5) ; Use ABD, minterm is A or B, don't MOVE.W #$8000,bltcon1(A5) ; shift A, shift B by 8 MOVE.L xt_NormalTextPlane(A2),D3 ; Address of the normal text plane MOVE.W xt_FontSelect(A2),D6 ; Get the address of the font data LSL.W #2,D6 LEA xt_FontData(A2),A3 ADD.W D6,A3 MOVE.L (A3),A3 MOVE.L ARG1(SP),A4 ; Address of text string MOVE.W xt_CharHeight(A2),D7 MOVE.W xt_Flags(A2),D6 ; Get the Flags ANDI #SLIM_XTEXT,D6 ; and test if the programmer wants SLIM_XTEXT BNE SLIM_CHARS ; and go build the text the "slim" way if so ; else we're doing text the faster "fat" way MOVE.W XBLTSIZE(SP),D6 ; Get the blit size partial ORI #1,D6 ; and make blit size one word wide CMPI #8,D7 ; Can we do fast building? BNE SLOW_PAIRLOOP ; If not 8, do it the "slow" way PAIRLOOP: * The normal text plane is constructed here. * Do as much pre-calculating as possible before actually waiting for the * blitter to be ready for re-use. CLEAR D4 ; Get the address of the font data of MOVE.B (A4)+,D4 ; the next character LSL.W #4,D4 ; (This presumes that each char is 16 bytes) ADD.L A3,D4 CLEAR D5 ; Get font data of next in pair (if there's MOVE.B (A4)+,D5 ; not really a second character (odd-numbered LSL.W #4,D5 ; string lengths) then this second move of ADD.L A3,D5 ; data will be unnecessary, but at least is ; harmless since the buffer is *always* ; pair-sized and the speed improvement is ; great when handling two characters at once) CALLSYS WaitBlit ; (this is redundant the first time through) MOVE.L D4,bltapt(A5) MOVE.L D5,bltbpt(A5) MOVE.L D3,bltdpt(A5) MOVE.W D6,bltsize(A5) ; Bombs away! ADDQ.L #2,D3 ; Advance destination pointer to next word DBRA D2,PAIRLOOP * Done, so go start setting up the planes BRA PLANESET SLOW_PAIRLOOP: * The normal text plane is constructed here. * Done the "slow" way using a MULU because the character height isn't 8. * Do as much pre-calculating as possible before actually waiting for the * blitter to be ready for re-use. CLEAR D4 ; Get the address of the font data of MOVE.B (A4)+,D4 ; the next character ADD.W D4,D4 MULU D7,D4 ; Offset * 2 * CharHeight ADD.L A3,D4 CLEAR D5 ; Get font data of next in pair (if there's MOVE.B (A4)+,D5 ; not really a second character (odd-numbered ADD.W D5,D5 ; string lengths) then this second move of MULU D7,D5 ADD.L A3,D5 ; data will be unnecessary, but at least is ; harmless since the buffer is *always* ; pair-sized and the speed improvement is ; great when handling two characters at once) CALLSYS WaitBlit ; (this is redundant the first time through) MOVE.L D4,bltapt(A5) MOVE.L D5,bltbpt(A5) MOVE.L D3,bltdpt(A5) MOVE.W D6,bltsize(A5) ; Bombs away! ADDQ.L #2,D3 ; Advance destination pointer to next word DBRA D2,SLOW_PAIRLOOP * Done, so go start setting up the planes BRA PLANESET SLIM_CHARS: * OK, the programmer asked for SLIM_XTEXT, which is the half-size memory * buffer for text to be built using the processor rather than the blitter MOVE.L A5,-(SP) ; Save A5 during the SLIM build CLEAR D0 ; Build the byte-size modulo MOVE.B xt_MaxTextWidth(A2),D0 SUBQ #1,D0 MOVE.W D7,D1 ; Build the line height (-1 for DBRA) SUBQ #1,D1 CMPI #8,D7 ; Can we do fast building? BNE SLIM_SLOW_PAIRLOOP ; If not 8, do it the "slow" way SLIM_PAIRLOOP: * The normal "slim" text plane is constructed here. CLEAR D4 ; Get the address of the font data of MOVE.B (A4)+,D4 ; the next character LSL.W #3,D4 ; (This presumes that each char is 8 bytes) ADD.L A3,D4 MOVE.L D4,A0 CLEAR D5 ; Get font data of next in pair (if there's MOVE.B (A4)+,D5 ; not really a second character (odd-numbered LSL.W #3,D5 ; string lengths) then this second move of ADD.L A3,D5 ; data will be unnecessary, but at least is MOVE.L D5,A1 ; harmless since the buffer is *always* ; pair-sized and the speed improvement is ; great when handling two characters at once) MOVE.W D1,D6 ; Build the bltsize word MOVE.L D3,A5 SLIM_BUILD: MOVE.B (A0)+,(A5)+ MOVE.B (A1)+,(A5) ADD.L D0,A5 DBRA D6,SLIM_BUILD ADDQ.L #2,D3 ; Advance destination pointer to next word DBRA D2,SLIM_PAIRLOOP ; Count down the character pairs to print MOVE.L (SP)+,A5 ; Restore A5 at end of SLIM_BUILD * Done, so go start setting up the planes BRA PLANESET SLIM_SLOW_PAIRLOOP: * The normal "slim" text plane is slowly constructed here, slow because * the characters are other than 8 lines tall. CLEAR D4 ; Get the address of the font data of MOVE.B (A4)+,D4 ; the next character MULU D7,D4 ADD.L A3,D4 MOVE.L D4,A0 CLEAR D5 ; Get font data of next in pair (if there's MOVE.B (A4)+,D5 ; not really a second character (odd-numbered MULU D7,D5 ; string lengths) then this second move ADD.L A3,D5 ; will be unnecessary, but at least is MOVE.L D5,A1 ; harmless since the buffer is *always* ; pair-sized and the speed improvement is ; great when handling two characters at once) MOVE.W D1,D6 ; Build the bltsize word MOVE.L D3,A5 SLIM_SLOW_BUILD: MOVE.B (A0)+,(A5)+ MOVE.B (A1)+,(A5) ADD.L D0,A5 DBRA D6,SLIM_SLOW_BUILD ADDQ.L #2,D3 ; Advance destination pointer to next word DBRA D2,SLIM_SLOW_PAIRLOOP ; Count down the pairs to print MOVE.L (SP)+,A5 ; Restore A5 at end of SLIM_BUILD * Done, so fall into starting setting up the planes PLANESET: * Well, that was quick, wasn't it. Here all of the required planes (except * the bothersome Inverted Text Plane) are ready to go. So let's figure * out how to initialize the plane pointers in the BitMap ... LEA xt_TextBitMap(A2),A3 LEA bm_Planes(A3),A4 ; Get address of first plane pointer CLEAR D0 ; Set up the pen-test mask MOVE.W FRONTPEN(SP),D1 ; Fetch the foreground pen MOVE.W BACKPEN(SP),D2 ; and the background pen CLEAR D3 MOVE.B bm_Depth(A3),D3 ; Get the BitMap depth ... SUBQ.W #1,D3 ; ... and set the loop count for DBRA CLEAR D4 ; Clear the Inverted flag PLANELOOP: * First, find out if the foreground/background pattern for this plane * is 00, 01, 10 or 11. based on the pattern, select the associated * plane pointer for the BitMap BTST D0,D1 ; If the bit is set in the foreground pen BNE PAT_ONE ; then go process 1x combinations * Else we have a 0x combination. Which one is it? BTST D0,D2 ; This time test the background pen BNE PAT_01 ; and if set then our pattern is 01 PAT_00: MOVE.L xt_AllClearPlane(A2),A3 ; This plane is the 00 plane BRA PLANE_STUFF PAT_01: * The dreaded Inverse Text Plane selector. If it doesn't exist yet, * I have to create it now. MOVE.L xt_InverseTextPlane(A2),A3 ; This plane is the inverse plane TST.B D4 ; Test our Inverted Plane flag BNE PLANE_STUFF ; and skip this mess if it's already set ; else we'll have to invert it. ADDQ.B #1,D4 ; Set the inversion flag * OK, so use the blitter inversion algorithm: Dest = NOT SRC. CLEAR D5 MOVE.B xt_MaxTextWidth(A2),D5 ; Build the Group-of-2 values: MOVE.W ARG2+2(SP),D6 ADDQ.W #1,D6 ; Get the first multiple of 2 that's greater ANDI.W #$FFFE,D6 ; than or equal to the character count, and SUB.W D6,D5 ; subtract that from the total buffer width ; to make the Group-of-2 row modulo LSR.W #1,D6 ; Turn char count into pair count OR.W XBLTSIZE(SP),D6 ; and prepare for starting the blitter MOVEM.L D0-D1,-(SP) CALLSYS WaitBlit ; Wait for the blitter before I jam it. MOVEM.L (SP)+,D0-D1 MOVE.L xt_NormalTextPlane(A2),bltbpt(A5) MOVE.L A3,bltdpt(A5) MOVE.W D5,bltbmod(A5) ; Set up the SRCB and DEST modulos MOVE.W D5,bltdmod(A5) MOVE.W #$0533,bltcon0(A5) MOVE.W #$0000,bltcon1(A5) MOVE.W D6,bltsize(A5) ; Bombs away! BRA PLANE_STUFF PAT_ONE: * We've got a 1x pattern. Which one do you suppose it is? Hmm ... BTST D0,D2 ; This time, test the back pen only BNE PAT_11 PAT_10: * Normal Text Plane? No problem. MOVE.L xt_NormalTextPlane(A2),A3 BRA PLANE_STUFF PAT_11: MOVE.L xt_AllSetPlane(A2),A3 ; This plane must have all bits set * and fall into ... PLANE_STUFF: * OK, so A3 has the address of this plane's data. Stuff that baby * into the BitMap structure. MOVE.L A3,(A4)+ ADDQ #1,D0 ; Advance our mask to the next position DBRA D3,PLANELOOP ; Loop on the depth of the BitMap * Now, all done with the private use of the blitter. Here, I would prefer * to retain exclusive use of the blitter even throughout the call to * BlitBMRP below, but the system won't let me. Too bad! CALLSYS DisownBlitter * Well, now the BitMap is all ready to blast out our new line * of text. Wasn't that fun? Now the simple final stroke: zap that * data into the RastPort, using the ever-popular, cleverly-named * BltBitMapRastPort function (if Dale wasn't so good, I'd suggest * that we take him out and shoot him for that name). * * BlitBMRP wants: * * A0 = Source BitMap * A1 = Destination RastPort * A6 = GfxBase * * D0 = Source X * D1 = Source Y * D2 = Destination X * D3 = Destination Y * D4 = Pixel Width of block to be moved * D5 = Scan-line Height of block to be moved * D6 = Minterm CLEAR D5 MOVE.W xt_CharHeight(A2),D5 ; Height of transfer MOVE.W #XTEXT_CHARWIDTH,D4 ; Create the blit width ... MOVE.W ARG2+2(SP),D3 ; Character count MULU D3,D4 ; Width of transfer (creates LONG) MOVE.L ARG4(SP),D3 ; Get the Y position into D3 MOVE.L ARG3(SP),D2 ; Get the X position into D2 CLEAR D1 ; Source x and y are 0 CLEAR D0 MOVE.L xt_OutputRPort(A2),A1 ; and get the RPort of the display LEA xt_TextBitMap(A2),A0 ; Get the address of the BitMap arg * The DrawMode defines what minterm we use and which routine we call. CMP.W #RP_JAM1,DRAWMODE(SP) ; Are we doing JAM1? BEQ DO_JAM1 * The DrawMode can be JAM2 or COMPLEMENT. Which is it, hmm? MOVE.L #$C0,D6 ; Minterm (simple transfer) for JAM2 CMP.W #RP_JAM2,DRAWMODE(SP) ; Is it really JAM2? BEQ BBMRP ; Branch if so MOVE.L #$60,D6 ; Only other is complement mode BBMRP: CALLSYS BltBitMapRastPort ; Do the normal (fast) BBMRP BRA RETURN DO_JAM1: * Call BltMaskBitMapRastPort, which is the same as BBMRP except that a * mask is used to cookie-cut the source into the destination. * JAM1 requires a mask, because JAM1 is cookie-cut! * The mask goes into A2. If either pen was non-zero then we built * the normal plane so use that as the mask, * else use the AllZeroPlane for the mask (which produces zip imagery!). * The minterm sez: cut me in, daddio. MOVE.B xt_DrawMode(A2),D6 ; Was this inverse video? ANDI.B #RP_INVERSVID,D6 BNE 1$ ; If so, use inverse JAM1 minterm MOVE.L #$E0,D6 ; else use normal JAM1 minterm BRA 2$ 1$ MOVE.L #$B0,D6 2$ TST.W FRONTPEN(SP) ; Was the front pen zero? BNE 3$ ; If not then get Normal for mask TST.W BACKPEN(SP) ; Was the back pen zero? BNE 3$ ; If not then get Normal for mask MOVE.L xt_AllClearPlane(A2),A2 ; AllClearPlane is the mask BRA 4$ 3$ MOVE.L xt_NormalTextPlane(A2),A2 ; use the plane as the mask 4$ CALLSYS BltMaskBitMapRastPort ; Do the not-as-fast BMBMRP RETURN: MOVEM.L (SP)+,A2-A6/D2-D7 LEA 8(SP),SP ; Release memory of local variables RTS END