* SpecialCodes for objects go in this include file. So does the * mine handling system. * NOTE : ALL SpecialCode routines (which have a pointer to them * placed in the AO_SpecialCode entry of the AlienObject structure) * MUST be re-entrant with respect to each alien (i.e., register A0 * MUST be left untouched). They can corrupt other registers freely * and also write to the variable table (pointed to by A6). They * can also cause inter-object interactions via pointers to the AO_ * structure for the other object if need be (e.g., Lander picking * up Body). * DO NOT CORRUPT REGISTER A0 OR ALL HELL WILL BREAK LOOSE! * ShipCode(a6,a0) * Perform special operations for ship. * d0-d1/a1 corrupt ShipCode move.b Anim_Flags(a0),d0 ;get death status and.b #_ANF_DISABLED,d0 ;dead? beq.s ShipCode4 ;skip if not rts ;else done ShipCode4 move.b AO_Flags(a0),d0 ;get ship status flags move.b d0,d1 ;copy them and.b #_AOF_DYING,d0 ;ship dying? bne.s ShipCode1 ;skip if so move.b d1,d0 ;copy flags back and.b #_AOF_HIT,d0 ;ship hit by something? bne.s ShipCode3 ;skip if so rts ;else done ShipCode3 moveq #10,d0 ;no. of explosion frames move.w d0,DeathTime(a6) ;set them off clr.w CurrXSpeed(a6) ;stop the ship st Brakes(a6) ;and prevent thrust and.b #_NAOF_HIT,d1 ;finished hitting or.b #_AOF_DYING,d1 ;now it's dying move.b d1,AO_Flags(a0) ;change ship stat rts ShipCode1 tst.w DeathTime(a6) ;finished explosion? beq.s ShipCode2 ;skip if so clr.w CurrXSpeed(a6) ;stop the ship rts ;else done ShipCode2 or.b #_ANF_DISABLED,Anim_Flags(a0) ;kill ship move.l Anim_Next(a0),a1 or.b #_ANF_DISABLED,Anim_Flags(a1) ;and flame move.l CurrentPlayer(a6),a1 moveq #_PDF_DEAD,d1 move.b d1,pd_Flags(a1) rts * BodyInit(a0,a6) * a0 = ptr to AO_ struct for Body * a6 = ptr to main program variables * Initialise Body position relative to landscape. If can't put * Body in a sensible position at this landscape point, move it. * d0-d2/a1-a2 corrupt BodyInit move.l YTable(a6),a1 ;table ptrs move.l LandOff(a6),a2 move.w Anim_YPos(a0),d0 ;get Body Y pos subq.w #4,d0 BDIN_1 move.w d0,d1 ;copy Y pos add.w d1,d1 ;word index move.w 0(a1,d1.w),d1 ;get YTable entry = YH move.w Anim_XPos(a0),d2 ;x pos lsr.w #4,d2 add.w d2,d2 ;word index move.w 0(a2,d2.w),d2 ;get Landscape entry add.w LandYHgt(a6),d2 ;make true Y offset = YL cmp.w d2,d1 ;below landscape surface? bcc.s BDIN_2 ;skip if so addq.w #8,d0 ;else try another Y cmp.w #196,d0 ;too far down? bcs.s BDIN_1 ;back if not * Here, we're at a deep trough. So relocate our Body and try again. move.w #180-4,d0 ;initial Y pos bsr Random ;change X position move.w Seed(a6),d1 and.w MaxScrPos(a6),d1 ;constrain to screen limits move.w d1,Anim_XPos(a0) ;set it move.w d0,Anim_YPos(a0) bra.s BDIN_1 * Here, we're below the landscape surface, so set Y pos, and * change the SpecialCode to point to the laser hit detection * code. BDIN_2 addq.w #4,d0 move.w d0,Anim_YPos(a0) lea BodyCode(pc),a1 move.l a1,AO_SpecialCode(a0) ;check for laser hits rts * BodyCode1(a0,a6) * a0 = ptr to AO_ struct for Body * a6 = ptr to main program variables * Perform Body operations once kidnapped. Fall through to * normal BodyCode if not dead. * d0/a1 corrupt BodyCode1 move.l AO_KidnapPtr(a0),a1 ;check Lander move.b Anim_Flags(a1),d0 ;& see if dead and.b #_ANF_DISABLED,d0 ;is it dead? beq.s BC1_2 ;skip if not * Here, the Lander has been shot away. Begin the falling sequence. lea BodyCode2(pc),a1 move.l a1,AO_SpecialCode(a0) rts BC1_2 move.w Anim_YPos(a0),d0 ;get Body Y pos subq.w #1,d0 ;-1 cmp.w #MIN_SY,d0 ;off top of play area? bhi.s BC1_1 ;skip if not moveq #_ANF_DISABLED,d0 ;else kill it move.b d0,Anim_Flags(a0) clr.l AO_SpecialCode(a0) move.l AO_ScanLoc(a0),a1 ;zero out move.l AO_ScanBit1(a0),d0 ;scanner bits not.l d0 ;for dead Body and.l d0,(a1) rts ;and done BC1_1 move.w d0,Anim_YPos(a0) ;replace y position, then do... * BodyCode(a0,a6) * a0 = ptr to AO_ struct for Body * a6 = ptr to main program variables * Perform 'Body hit by laser' function. If not hit, just * exit cleanly. If hit, then check if this is the last * Body and if so, signal the End Of The World... * d0/a1 corrupt BodyCode move.b AO_Flags(a0),d0 ;check Body status and.b #_AOF_HIT,d0 ;hit by laser? beq.s BC0_1 ;exit if not move.b #_ANF_DISABLED,d0 ;else this Body is move.b d0,Anim_Flags(a0) ;dead... move.l AO_ScanLoc(a0),a1 ;zero out move.l AO_ScanBit1(a0),d0 ;scanner bits not.l d0 ;for dead Body and.l d0,(a1) * NOTE : all of the pd_Bodies subtractions have been reworked like * this to prevent the -1 Body count bug (which results in mayhem on * screen plus 65,536,000 added to the score!!!). move.l CurrentPlayer(a6),a1 ;subtract 1 from move.w pd_Bodies(a1),d0 beq.s BC0_2 subq.w #1,d0 move.w d0,pd_Bodies(a1) ;Body count bne.s BC0_1 ;skip if some left BC0_2 bsr EndOfWorld ;else oh, oh... BC0_1 rts * BodyCode2(a0,a6) * a0 = ptr to AO_ struct for Body * a6 = ptr to main program variables * Perform Body operations if kidnapping Lander dies. * Basically cause descent, and if Body hits floor * too hard (i.e., from too high up) then Body dies. * Also checks to see if ship has rescued body. * d0-d2/a1 corrupt BodyCode2 move.w Anim_XPos(a0),d0 ;get Body X Pos add.w CurrXPos(a6),d0 and.w MaxScrPos(a6),d0 ;position rel. to ship * Here, check if Body and Ship are close together (i.e., ship is * picking up Body) move.l ShipAnim(a6),a1 move.w Anim_XPos(a1),d1 move.w d1,d2 ;ship x add.w #14,d2 ;ship x + 18 subq.w #4,d1 ;make life easier! cmp.w d1,d0 ;Body x > ship x? bls.s BC2_4 ;skip if not cmp.w d2,d0 ;Body x < (ship x + 14)? bcc.s BC2_4 ;skip if not move.w Anim_YPos(a0),d0 move.w Anim_YPos(a1),d1 move.w d1,d2 ;ship y ; addq.w #8,d2 ;ship y + 8 ; addq.w #4,d2 ;ship y + 12 add.w #16,d2 ;ship y + 16 (was 12) cmp.w d1,d0 ;body y > ship y? bls.s BC2_4 ;skip if not cmp.w d2,d0 ;body y < (ship y + 16) ? bcc.s BC2_4 ;skip if not * If we reach here, then the ship and the Body are close together * and we've rescued the Body. lea BodyCode3(pc),a1 ;change Body move.l a1,AO_SpecialCode(a0) ;SpecialCode ; or.b #_AOF_RESCUED,AO_Flags(a0) ;signal rescued move.b #_AOF_RESCUED,AO_Flags(a0) rts * Come here if still not rescued. Begin the descent to the landscape * and if we hit the landscape too hard, then the Body dies. BC2_4 move.w Anim_YPos(a0),d0 ;Body Y pos add.w AO_YMove(a0),d0 ;move down a bit move.w d0,Anim_YPos(a0) move.w AO_YCnt(a0),d0 ;do acceleration addq.w #1,d0 ; and.w #$F,d0 and.w #$7,d0 ;counter cycled back? move.w d0,AO_YCnt(a0) bne.s BC2_1 ;skip if not addq.w #1,AO_YMove(a0) ;else vert speed + 1 * Here, see if the Body has hit the ground. If not, continue moving * downwards. Use Landscape data table to determine if we're there. BC2_1 move.w Anim_YPos(a0),d0 ;get y position move.l YTable(a6),a1 ;YTable move.w d0,d1 subq.w #4,d1 ;y-4 for below ground add.w d1,d1 move.w 0(a1,d1.w),d1 ;get YTable entry move.w Anim_XPos(a0),d2 ;x position lsr.w #4,d2 ;x/16=array index add.w d2,d2 ;WORD index move.l LandOff(a6),a1 ;ptr to array move.w 0(a1,d2.w),d2 ;get landscape entry add.w LandYHgt(a6),d2 ;landscape height cmp.w d2,d1 ;below surface? bcs.s BC2_2 ;exit if not ; cmp.w #MAX_SY-20,d0 ;Body hit bottom? ; bcs.s BC2_2 ;skip if not move.w AO_YMove(a0),d0 ;get vertical speed cmp.w #4,d0 ;hit ground too fast? bls.s BC2_3 ;skip if not * Here, the Body has hit the ground from too high up. Kill it off. or.b #_ANF_DISABLED,Anim_Flags(a0) move.l AO_ScanLoc(a0),a1 ;zero out move.l AO_ScanBit1(a0),d0 ;scanner bits not.l d0 ;for dead Body and.l d0,(a1) move.l CurrentPlayer(a6),a1 ;now reduce the move.w pd_Bodies(a1),d0 ;Body count beq.s BC2_2A subq.w #1,d0 move.w d0,pd_Bodies(a1) bne.s BC2_2 ;skip if any left * Here, we trigger landscape disappearance, mutant conversion of * remaining Landers, when all Bodies have been killed off. BC2_2A bsr EndOfWorld * Whether dead or not, come here if we're at ground level... * Restore the original BodyCode whether dead or not-because * if the Body is dead, it won't get called, and if it isn't, * then it'll be needed... BC2_3 clr.w AO_YMove(a0) ;no vertical speed lea BodyCode(pc),a1 move.l a1,AO_SpecialCode(a0) * ...else exit for another round of the same. BC2_2 rts * BodyCode3(a0,a6) * a0 = ptr to AO_ struct for Body * a6 = ptr to main program variables * Handle rescued Bodies. BodyCode3 move.l ShipAnim(a6),a1 move.w MaxScrPos(a6),d0 sub.w CurrXPos(a6),d0 add.w Anim_XPos(a1),d0 ;true body X pos addq.w #4,d0 ;plus a displacement move.l Seed(a6),d1 and.w #3,d1 subq.w #1,d1 ;plus a random wobble add.w d1,d0 ;factor and.w MaxScrPos(a6),d0 move.w d0,Anim_XPos(a0) ;= body x pos move.w Anim_YPos(a1),d0 ;ship y pos addq.w #7,d0 move.w d0,Anim_YPos(a0) ;this is body y pos move.l YTable(a6),a1 ;YTable ptr move.w d0,d1 ;copy Y position subq.w #4,d1 add.w d1,d1 move.w 0(a1,d1.w),d1 ;get YTable entry move.l LandOff(a6),a1 move.w Anim_XPos(a0),d2 ;get x position lsr.w #4,d2 add.w d2,d2 move.w 0(a1,d2.w),d2 ;get landscape entry add.w LandYHgt(a6),d2 ;landscape height cmp.w d2,d1 ;below surface? bcs.s BC3_1 ;skip if not ; move.w #MAX_SY,d1 ; sub.w #10,d1 ;y limit - 10 ; cmp.w d1,d0 ;body y > above? ; bls.s BC3_1 ;skip if not * Here, if rescued, restore original SpecialCode and give player a * bonus for rescuing the Body. lea BodyCode(pc),a1 move.l a1,AO_SpecialCode(a0) clr.b AO_Flags(a0) ;no longer rescued move.l CurrentPlayer(a6),a1 move.l pd_Score(a1),d0 moveq #0,d1 move.w #500,d1 ;rescue Body:500 points! add.l d1,d0 move.l d0,pd_Score(a1) BC3_1 rts * LanderCode(a0,a6) * a0 = ptr to AlienObject structure (Anim header!) * a6 = ptr to main program variables * Perform Lander operation. For now, just initialise and then * move the lander. * d0/a1 corrupt LanderCode move.w #160,Anim_YPos(a0) ;set Y Position bsr Random move.l Seed(a6),d0 ;get random no. and.w MaxScrPos(a6),d0 move.w d0,Anim_XPos(a0) ;set X Position move.b #_ANF_SAMEFRAME,d0 move.b d0,Anim_Flags(a0) clr.b AO_Flags(a0) clr.l AO_KidnapPtr(a0) ;no Body yet move.l BodyList(a6),d0 move.l d0,AO_WhatBody(a0) ;ptr to Bodies lea DoLander(pc),a1 move.l a1,AO_SpecialCode(a0) tst.b Seed(a6) ;top byte <0? bpl.s LanderSet ;skip if not neg.w AO_XMove(a0) ;else change direction LanderSet clr.w AO_YMove(a0) ;no y movement yet bsr Random ;another random number move.l Seed(a6),d0 and.w KDThresh(a6),d0 move.w d0,AO_BCount(a0) ;ticker for hunting rts * DoLander(a0,a6) * a0 = ptr to AlienObject structure (Anim header!) * a6 = ptr to main program variables * Handle Lander operations. * Note : new way of setting lander hunting. Use a countdown clock * stored in AO_BCount. When it hits zero, a-hunting we will go. * Also, Lander now tries to find the Body closest to it for hunting. DoLander tst.b NoLand(a6) ;Planet gone? bne DoLander_12 ;skip if so move.b AO_Flags(a0),d0 ;check Lander status move.b d0,d1 and.b #_AOF_HIT,d0 ;hit by laser? beq.s DoLander_2 ;skip if not eor.b #_AOF_HIT,d1 move.b d1,AO_Flags(a0) and.b #_NANF_SAMEFRAME,Anim_Flags(a0) DoLander_2 move.b Anim_Flags(a0),d0 ;check Anim flags and.b #_ANF_SAMEFRAME,d0 ;not animating? bne.s DoLander_1 ;skip if not move.l Anim_CFrame(a0),a1 move.l AnFr_Next(a1),d0 ;done explosion cmp.l d0,a1 ;animating? bne.s DoLander_1 ;skip if not move.b #_AOF_DYING,d0 ;else this object is move.b d0,AO_Flags(a0) ;dying... move.l CurrentPlayer(a6),a1 subq.w #1,pd_Landers(a1) move.l AO_KidnapPtr(a0),d0 ;dropping a Body? beq.s DoLander_2a ;skip if not lea BodyCode2(pc),a1 ;else change exg d0,a1 ;SpecialCode move.l d0,AO_SpecialCode(a1) ;for Body moveq #1,d0 move.w d0,AO_YMove(a1) clr.w AO_YCnt(a1) * Here, we do a test for whether we're playing Defender Plus. If so, * we can leave a power-up behind to pick up. DoLander_2a tst.b GamePlus(a6) ;which game? beq.s DoLander_2x ;skip if Classic * Here, we're playing Defender Plus. Allow this AO_ structure to be re-used * for the Power-Up. Here determine whether or not we'll have a power-up, & * if not, set the re-use pointer to zero. moveq #0,d0 ;reuse pointer bsr Random ;make a random number move.w Seed(a6),d1 ;get it and.w #$0F,d1 ;lowest 4 bits zero? bne.s DoLander_2y ;skip if not * Here, we're having a power-up, so set the re-use pointer to * point to this dead Lander's AO_ struct. move.l a0,d0 DoLander_2y move.l d0,PuPtr(a6) move.l CurrentPlayer(a6),a1 move.l d0,pd_PuPtr(a1) DoLander_2x rts * Come here if Lander functioning normally. DoLander_1 move.w Anim_XPos(a0),d0 ;current x coord add.w AO_XMove(a0),d0 ;movement value and.w MaxScrPos(a6),d0 ;constrain to screen move.w d0,Anim_XPos(a0) ;replace x coord ; add.w CurrXPos(a6),d0 ; and.w MaxScrPos(a6),d0 move.w Anim_YPos(a0),d0 ;current y coord add.w AO_YMove(a0),d0 ;movement value move.w d0,Anim_YPos(a0) ;replace y coord * Before doing terrain following, see if kidnapping a Body. If so, * skip terrain following. move.b AO_Flags(a0),d1 move.b d1,d2 and.b #_AOF_SNATCHING,d1 ;taking a Body? bne DoLander_4 ;skip if so * Here handle terrain following. First check if we're descending after * having a Body shot from the underside. If so, descend in 1 pixel steps * until we're at the correct height. Then begin moving sideways again * as normal. and.b #_AOF_LOSTIT,d2 ;just lost a Body? beq.s DoLander_1h ;skip if not move.w AO_YMove(a0),d1 ;get movement cmp.w #-1,d1 ;moving up? beq DoLander_14 ;skip if so cmp.w #1,d1 ;moving down? beq DoLander_15 ;skip if so * Here it isn't ascending/descending because of Body loss, so * continue as normal. DoLander_1h add.w #20,d0 ;current y + 20 add.w d0,d0 ;index into YTable move.l YTable(a6),a1 move.w 0(a1,d0.w),d0 ;get YTable entry =YH move.w Anim_XPos(a0),d1 addq.l #8,d1 and.w MaxScrPos(a6),d1 lsr.w #4,d1 ;index into LandScape add.w d1,d1 move.l LandOff(a6),a1 move.w 0(a1,d1.w),d1 ;get Landscape offset =YL add.w LandYHgt(a6),d1 moveq #0,d2 ;this is YMove cmp.w d0,d1 ;heights equal (YH=YL)? beq.s DoLander_1a ;skip if so bcs.s DoLander_1b ;skip if YLYH then lander bra.s DoLander_1a ;should move down DoLander_1b moveq #-4,d2 ;lander should move up DoLander_1a move.w d2,AO_YMove(a0) ;set terrain following movement bsr LMine ;do missile if wanted move.b AO_Flags(a0),d0 move.b d0,d1 and.b #_AOF_HUNTING,d1 ;looking for body? bne.s DoLander_3 ;skip if so and.b #_AOF_SNATCHING,d0 ;got body? bne DoLander_4 ;skip if so * Here, check the countdown clock to hunting. Reset clock to KDThresh * value just in case this kidnap attempt unsuccessful for some reason * once countdown to zero achieved. Thus we can try again later. move.w AO_BCount(a0),d0 ;reduce ticker subq.w #1,d0 and.w KDThresh(a6),d0 ;prevent excess time rollover move.w d0,AO_BCount(a0) beq.s DoLander_5 ;set hunting if zero rts ;else done DoLander_5 moveq #_AOF_HUNTING,d0 or.b d0,AO_Flags(a0) ;set hunting flag rts * Come here if hunting. Select a Body to kidnap. DoLander_3 move.l AO_KidnapPtr(a0),d0 ;got body to hunt for? bne DoLander_7 ;skip if so move.l AO_WhatBody(a0),a1 ;get Body move.w Anim_ID(a1),d0 ;check object ID cmp.w #_AL_BODY,d0 ;genuine body? beq.s DoLander_6 ;skip if so move.l BodyList(a6),d0 ;round again in case move.l d0,AO_WhatBody(a0) ;hunting Lander killed! rts * We come here if an attempt to select a Body for kidnapping has * been thwarted (already kidnapped/rescued/dead etc). DoLander_6b move.l Anim_Next(a1),a1 ;get next Body move.l a1,AO_WhatBody(a0) ;for next test rts * Here, check if Body is available to be hunted/snatched. DoLander_6 move.b Anim_Flags(a1),d0 and.b #_ANF_DISABLED,d0 ;body already dead? bne.s DoLander_6b ;don't snatch it if so move.b AO_Flags(a1),d0 move.b d0,d1 and.b #_AOF_SNATCHED,d1 ;already snatched? bne.s DoLander_6b ;don't snatch if so move.b d0,d1 and.b #_AOF_HUNTED,d1 ;already hunted by another? bne.s DoLander_6b ;don't hunt if so and.b #_AOF_RESCUED,d0 ;rescued state? bne.s DoLander_6b ;don't snatch if so * Now see if this Body is close enough to this Lander. If so, * we go and get it. move.w Anim_XPos(a0),d0 ;get Lander position move.w Anim_XPos(a1),d1 ;get Body position sub.w d0,d1 ;check how close it is move.w MaxScrPos(a6),d0 and.w d0,d1 ;normalise separation lsr.w #1,d0 cmp.w d0,d1 ;check which side it's on bhi.s DoLander_11 ;skip if Body to Left * Here, Body is to right. Check if close enough. cmp.w #$200,d1 ;are we close to it? bhi.s DoLander_6b ;leave if not bra.s DoLander_6a ;else go kidnap it * Here, Body is to left. Check if close enough. DoLander_11 cmp.w #$2000-$200,d1 ;are we close to it? bcs.s DoLander_6b ;leave if not * Come here if Body is available to be kidnapped AND is close enough * to this Lander. From here, we set Lander to go find this Body & * kidnap it. DoLander_6a move.b #_AOF_HUNTED,AO_Flags(a1) ;set this Body hunted! move.l a1,AO_KidnapPtr(a0) ;set kidnap ptr move.l a0,AO_KidnapPtr(a1) ;this is the kidnapper ; move.l Anim_Next(a1),BodyPtr(a6) ;& update next move.l Anim_XPos(a1),d0 ;get coords in one go sub.w #10,d0 ;y=y-10 swap d0 subq.w #3,d0 ;x=x-3 and.w MaxScrPos(a6),d0 swap d0 ;correct order move.l d0,AO_XCnt(a0) ;& store in one go move.b #_AOF_SNATCHED,AO_Flags(a1) rts * Come here if this Lander has selected a Body for kidnap. Check if we're * on top of it, and if so, complete the kidnap operation. DoLander_7 move.w AO_XCnt(a0),d0 ;get body x pos move.w Anim_XPos(a0),d1 sub.w d0,d1 ;this lot gets the value bpl.s DoLander_7a ;abs(landerx-bodyx) neg.w d1 DoLander_7a cmp.w #2,d1 ;lander close to body? bls.s DoLander_8 ;skip if so rts ;else done * Come here if we're on top of the Body. Kidnap it! DoLander_8 move.w d0,Anim_XPos(a0) ;set lander position moveq #0,d0 ;stop horiz movement move.w d0,AO_XMove(a0) move.w AO_YCnt(a0),d0 ;get body y pos cmp.w Anim_YPos(a0),d0 ;lander got body? beq.s DoLander_9 ;skip if so moveq #1,d0 ;set lander to move down move.w d0,AO_YMove(a0) rts * Come here if Lander touches body. Begin taking to top of screen. DoLander_9 move.b AO_Flags(a0),d0 and.b #_NAOF_HUNTING,d0 ;lander is now or.b #_AOF_SNATCHING,d0 ;snatching move.b d0,AO_Flags(a0) moveq #-1,d0 ;set lander to climb move.w d0,AO_YMove(a0) ;to top of screen lea BodyCode1(pc),a1 ;and the Body too! move.l a1,d0 move.l AO_KidnapPtr(a0),a1 move.l d0,AO_SpecialCode(a1) rts * Come here if snatching Body. Check if we've hit top of screen. DoLander_4 move.w Anim_YPos(a0),d0 ;Lander Y pos cmp.w #MIN_SY,d0 ;top of screen? bhi.s DoLander_10 ;skip if not * Here, we wait for Body to be completely absorbed into the Lander * as set by BodyCode. ; move.l a0,DebugL(a6) ; move.l AO_KidnapPtr(a0),DebugL+4(a6) moveq #0,d0 move.w d0,AO_XMove(a0) ;stop moving upwards move.w d0,AO_YMove(a0) move.l AO_KidnapPtr(a0),a1 move.b Anim_Flags(a1),d0 ;check if Body and.b #_ANF_DISABLED,d0 ;snatch complete beq.s DoLander_10 ;done if not * Here, Body has been completely kidnapped. Turn Lander into a Mutant. or.b #_ANF_DISABLED,d0 move.b d0,Anim_Flags(a1) move.l CurrentPlayer(a6),a1 move.w pd_Bodies(a1),d0 ;adjust Body count beq.s DoLander_22 subq.w #1,d0 move.w d0,pd_Bodies(a1) bne.s DoLander_12 ;skip if any left * Here, trigger Landscape disappearance & mutant conversion * if all Bodies have been destroyed. DoLander_22 bsr EndOfWorld * Here, convert THIS Lander into a Mutant. Also come here if landscape has * gone (i.e., no more planet) if this Lander didn't cause the end of the * world... DoLander_12 lea DoMutant(pc),a1 ;else Lander becomes move.l a1,AO_SpecialCode(a0) ;a mutant! addq.w #1,Anim_ID(a0) move.l AlienAnFr+4(a6),d0 move.l d0,Anim_Frames(a0) move.l d0,Anim_CFrame(a0) clr.l AO_KidnapPtr(a0) move.b #_ANF_SAMEFRAME,Anim_Flags(a0) clr.b AO_Flags(a0) move.w #150,d0 move.w d0,AO_Points(a0) ;150 pts for killing Mutant! moveq #-1,d0 clr.w d0 move.l d0,AO_ScanMsk1(a0) ;scanner dot changes! rts * Come here if Lander not at top of screen. Now check if the Body * has been shot from under the Lander. DoLander_10 move.l AO_KidnapPtr(a0),a1 ;ptr to Body move.b Anim_Flags(a1),d0 ;get Body flags and.b #_ANF_DISABLED,d0 ;Body dead? beq.s DoLander_13 ;skip if not * Here, old Body has been shot away, so resume hunting. clr.l AO_KidnapPtr(a0) moveq #_AOF_HUNTING+_AOF_LOSTIT,d0 move.b d0,AO_Flags(a0) * Come here if either Body dead & hunting resumed, or Body live & * being kidnapped. DoLander_13 rts * Come here if moving up after Body snatch, & Body shot away. DoLander_14 move.w Anim_YPos(a0),d1 ;check height add.w #20,d1 move.l YTable(a6),a1 ;get YTable offset add.w d1,d1 ;WORD index into YTable! move.w 0(a1,d1.w),d1 cmp.w LandYHgt(a6),d1 ;at normal Landscape height? beq.s DoLander_16 ;skip if equal bhi.s DoLander_17 ;and skip if below landscape moveq #1,d0 move.w d0,AO_YMove(a0) ;else make it move down DoLander_17 rts * Come here if moving down after Body snatch, & Body shot away. DoLander_15 move.w Anim_YPos(a0),d1 ;check height add.w #20,d1 move.l YTable(a6),a1 ;get YTable offset add.w d1,d1 ;WORD index into YTable! move.w 0(a1,d1.w),d1 cmp.w LandYHgt(a6),d1 ;at normal Landscape height? beq.s DoLander_16 ;skip if equal bcs.s DoLander_17 ;and skip if above landscape moveq #-1,d0 move.w d0,AO_YMove(a0) ;else make it move up rts * Come here if normal Lander service is to be resumed. DoLander_16 clr.w AO_YMove(a0) ;stop vertical movement move.b AO_Flags(a0),d0 ;signal no longer lost Body and.b #_NAOF_LOSTIT,d0 move.b d0,AO_Flags(a0) move.w Seed(a6),d0 ;get random number bmi.s DoLander_18 ;skip if negative moveq #2,d0 move.w d0,AO_XMove(a0) ;restore horizontal movement rts DoLander_18 moveq #-2,d0 move.w d0,AO_XMove(a0) ;restore horizontal movement rts * MutantCode(a0,a6) * a0 = ptr to AO_ struct for mutant * a6 = ptr to main program vars * Initialise Mutant position etc. MutantCode bsr Random ;make new random no. move.w Seed(a6),d0 ;get random number and.w #1,d0 ;0 or 1 add.w d0,d0 ;word index lea MutantStart(a6),a1 ;ptr to Mutant x pos'n move.w 0(a1,d0.w),d0 ;get which one move.l Seed(a6),d1 ;random number again move.l d1,d2 ;copy it and.w #$7F,d1 ;range=0 to 127 add.b d1,d1 ; x 2 ext.w d1 ;make negative if so asr.w #1,d1 ;/2 again add.w d1,d0 ;add to start x pos and.w MaxScrPos(a6),d0 ;normalise to screen move.w d0,Anim_XPos(a0) ;this is X position rol.w #4,d2 ;get random number and.w #$3F,d2 ;range=0 to 63 add.w #MIN_SY,d2 ;add on minimum y pos move.w d2,Anim_YPos(a0) ;this is Y position ; bsr SetPos ;set position lea DoMutant(pc),a1 ;mutant controller move.l a1,AO_SpecialCode(a0) ;point to it rts * DoMutant(a0,a6) DoMutant move.b AO_Flags(a0),d0 ;check alien status move.b d0,d1 and.b #_AOF_HIT,d0 ;hit by laser? beq.s DoMutant_3 ;skip if not eor.b #_AOF_HIT,d1 move.b d1,AO_Flags(a0) and.b #_NANF_SAMEFRAME,Anim_Flags(a0) DoMutant_3 move.b Anim_Flags(a0),d0 ;check Anim flags and.b #_ANF_SAMEFRAME,d0 ;not animating? bne.s DoMutant_4 ;skip if not move.l Anim_CFrame(a0),a1 move.l AnFr_Next(a1),d0 ;done explosion cmp.l d0,a1 ;animating? bne.s DoMutant_4 ;skip if not move.b #_AOF_DYING,d0 ;else this object is move.b d0,AO_Flags(a0) ;dying... move.l CurrentPlayer(a6),a1 subq.w #1,pd_Mutants(a1) * Here, check to see if we're playing Defender Plus. If so, allow * power-ups to be dropped. tst.b GamePlus(a6) ;which game? beq.s DoMutant_2x ;skip if Classic * Here, we're playing Defender Plus. Allow this AO_ structure to be re-used * for the Power-Up. Here determine whether or not we'll have a power-up, & * if not, set the re-use pointer to zero. moveq #0,d0 ;reuse pointer bsr Random ;make a random number move.w Seed(a6),d1 ;get it and.w #$0F,d1 ;lowest 4 bits zero? bne.s DoMutant_2y ;skip if not * Here, we're having a power-up, so set the re-use pointer to * point to this dead Mutant's AO_ struct. move.l a0,d0 DoMutant_2y move.l d0,PuPtr(a6) move.l CurrentPlayer(a6),a1 move.l d0,pd_PuPtr(a1) DoMutant_2x rts DoMutant_4 bsr Random move.l Seed(a6),d0 ;get random number and.w #$0F,d0 subq.w #8,d0 ;this is X add-on (-8 to +7) swap d0 and.w #$0F,d0 subq.w #8,d0 ;this is Y add-on (-8 to +7) move.w Anim_YPos(a0),d1 ;get Y position add.w d0,d1 ;new Y position cmp.w #MIN_SY,d1 ;off top of screen? bcc.s DoMutant_1 ;skip if not move.w #MAX_SY,d1 ;else put on bottom DoMutant_1 cmp.w #MAX_SY,d1 ;off bottom of screen? bls.s DoMutant_2 ;skip if not move.w #MIN_SY,d1 ;else put on top DoMutant_2 move.w d1,Anim_YPos(a0) ;save new Y position swap d0 ;get X add-on move.w Anim_XPos(a0),d1 ;get X position add.w d0,d1 ;update it and.w MaxScrPos(a6),d1 ;constrain to screen limits move.w d1,Anim_XPos(a0) ;& store back bsr LMine ;& throw a missile rts * BomberCode(a0,a6) * a0 = ptr to AO_ struct for Bomber * a6 = ptr to main program vars * Initialise Bomber position, then set * AO_SpecialCode to point to Bomber movement code. BomberCode move.l BInitList(a6),a1 ;initialiser list move.w BomberCount(a6),d0 ;counter move.w d0,d1 addq.w #1,d1 ;next one and.w #7,d1 move.w d1,BomberCount(a6) ;save it for next time add.w d0,d0 ;adjust for add.w d0,d0 ;longword entries add.w d0,a1 ;point to entry move.w (a1)+,Anim_XPos(a0) ;get start x pos move.w (a1)+,AO_XMove(a0) ;get start x speed move.b #_ANF_SAMEFRAME,d0 move.b d0,Anim_Flags(a0) clr.b AO_Flags(a0) bsr Random move.l Seed(a6),d0 ;initial counter and.w #$1FF,d0 ;constrain to limits move.w d0,AO_BCount(a0) ;and save add.w d0,d0 ;adjust for word size move.l BomberList(a6),a1 ;point to curve move.w 0(a1,d0.w),d0 ;get curve Y pos move.w d0,Anim_YPos(a0) ;and save it clr.w AO_YMove(a0) lea DoBomber(pc),a1 move.l a1,AO_SpecialCode(a0) rts * DoBomber(a0,a6) * a6 = ptr to main program variables * a0 = ptr to Bomber's AO_ structure * Perform Bomber functions. DoBomber move.b AO_Flags(a0),d0 ;check alien status move.b d0,d1 and.b #_AOF_HIT,d0 ;hit by laser? beq.s DoBomber_2 ;skip if not eor.b #_AOF_HIT,d1 move.b d1,AO_Flags(a0) and.b #_NANF_SAMEFRAME,Anim_Flags(a0) DoBomber_2 move.b Anim_Flags(a0),d0 ;check Anim flags and.b #_ANF_SAMEFRAME,d0 ;not animating? bne.s DoBomber_1 ;skip if not move.l Anim_CFrame(a0),a1 move.l AnFr_Next(a1),d0 ;done explosion cmp.l d0,a1 ;animating? bne.s DoBomber_1 ;skip if not move.b #_AOF_DYING,d0 ;else this object is move.b d0,AO_Flags(a0) ;dying... move.l CurrentPlayer(a6),a1 subq.w #1,pd_Bombers(a1) rts DoBomber_1 move.w Anim_XPos(a0),d0 ;current x coord add.w AO_XMove(a0),d0 ;movement value and.w MaxScrPos(a6),d0 ;constrain to screen move.w d0,Anim_XPos(a0) ;replace x coord move.w AO_BCount(a0),d0 ;get current Bomber count addq.w #1,d0 ;next one and.w #$1FF,d0 ;within curve limits move.w d0,AO_BCount(a0) ;save new count move.l BomberList(a6),a1 ;get list add.w d0,d0 move.w 0(a1,d0.w),d0 ;get new Y coord move.w d0,Anim_YPos(a0) ;and store it bsr BMine ;lay a mine rts * BaiterOn(a6) * a6 = ptr to main program variables * Activate the Baiter when time's up. Use a 'count-up' clock & * compare with preset alarm value. When alarm value matched or * exceeded, activate a Baiter! * d0/a1 corrupt BaiterOn move.l CurrentPlayer(a6),a0 ;this player move.l pd_BaiterClock(a0),d0 ;check count-up move.l pd_BaiterAlarm(a0),d1 addq.l #1,d0 cmp.l d1,d0 ;ready for the off? bcs.s BON_1 ;skip if not * Here, we've run out of time. Activate the dreaded Baiter. move.l pd_BaiterPtr(a0),a1 ;ptr to Baiter move.b Anim_Flags(a1),d0 ;get flags and.b #_ANF_DISABLED,d0 ;already dead? bne.s BON_2 ;bring to life if so move.l Anim_Next(a1),a1 ;2nd Baiter move.b Anim_Flags(a1),d0 ;get flags and.b #_ANF_DISABLED,d0 ;already dead? bne.s BON_2 ;bring to life if so move.l Anim_Next(a1),a1 ;3rd Baiter move.b Anim_Flags(a1),d0 ;get flags and.b #_ANF_DISABLED,d0 ;already dead? bne.s BON_2 ;bring to life if so move.l Anim_Next(a1),a1 ;4th Baiter move.b Anim_Flags(a1),d0 ;get flags and.b #_ANF_DISABLED,d0 ;already dead? beq.s BON_3 ;exit if not * Come here if one of the Baiter AO_ structures has _ANF_DISABLED set * (in other words it's awaiting activation). BON_2 move.w Anim_ID(a1),d0 ;now see if it's cmp.w #_AL_BAITER,d0 ;reserved for a bne.s BON_3 ;Baiter * We come here ONLY if the structure is free, AND it's ID code * is that of a Baiter (preset by InitSet() beforehand). move.b #_ANF_SAMEFRAME,Anim_Flags(a1) ;Activate it! st BAlert(a6) * Here reset the alarm so that the next Baiter appears after 30 seconds * so that if the player kills the old one off, he'll find reinforcements * to hand! moveq #0,d0 move.w #$300,d0 move.l d0,pd_BaiterAlarm(a0) * Come straight here if time isn't up. Reset the clock for the next * Baiter if we've got one (or there isn't one online to activate). BON_3 moveq #0,d0 ;reset clock BON_1 move.l d0,pd_BaiterClock(a0) rts * BaiterCode(a0,a6) * a0 = ptr to AO_Struct for calling Baiter * a6 = ptr to main program variables * Initialise the Baiter and set it running. This code is pre-loaded into * the AO_SpecialCode entry of the AO_ sturct, and gets called once the * BaiterOn() code above enables this struct for BlitPreComp(). BaiterCode move.l SVStartup(a6),a1 ;ptr to SpecialValues add.w #72,a1 ;point to Baiter entry move.w (a1)+,AO_Points(a0) ;initialise the move.w (a1)+,AO_XMove(a0) ;relevant Baiter move.w (a1)+,AO_YMove(a0) ;structure entries move.w (a1)+,AO_XOff(a0) move.w (a1)+,AO_YOff(a0) move.w (a1)+,AO_XDisp(a0) move.w (a1)+,AO_YDisp(a0) move.w (a1)+,AO_YLDisp(a0) move.w (a1)+,AO_ScanMsk1(a0) move.w (a1)+,AO_ScanMsk2(a0) move.l AlienAnFr+12(a6),d0 ;set image ptrs move.l d0,Anim_Frames(a0) ;for Baiter move.l d0,Anim_CFrame(a0) * This next lot is for safety's sake. move.w #_AL_BAITER,Anim_ID(a0) ;set Baiter ID move.b #_ANF_SAMEFRAME,Anim_Flags(a0) clr.b AO_Flags(a0) * Now set initial Baiter position & movement values. move.w CurrXPos(a6),d0 move.w MaxScrPos(a6),d1 move.w d1,d2 lsr.w #1,d2 add.w d2,d0 and.w d1,d0 move.w d0,Anim_XPos(a0) move.w #128,Anim_YPos(a0) move.w Seed(a6),d0 ;get random number move.w d0,d1 smi d0 ext.w d0 ;this creates -1 or 0 tst.w d1 spl d1 ext.w d1 neg.w d1 ;this creates +1 or 0 add.w d1,d0 move.w d0,AO_YMove(a0) clr.w AO_XMove(a0) * Now set up the AO_SpecialCode to point to the Baiter's own * operational code. lea DoBaiter(pc),a1 move.l a1,AO_SpecialCode(a0) rts * DoBaiter(a0,a6) * a0 = ptr to AO_ structure for calling Baiter * a6 = ptr to main program variables * Make Baiter fly. DoBaiter move.b AO_Flags(a0),d0 ;check alien status move.b d0,d1 and.b #_AOF_HIT,d0 ;hit by laser? beq.s DoB_1 ;skip if not eor.b #_AOF_HIT,AO_Flags(a0) and.b #_NANF_SAMEFRAME,Anim_Flags(a0) DoB_1 move.b Anim_Flags(a0),d2 ;check Anim flags and.b #_ANF_SAMEFRAME,d2 ;not animating? bne.s DoB_2 ;skip if not move.l Anim_CFrame(a0),a1 move.l AnFr_Next(a1),d2 ;done explosion cmp.l d2,a1 ;animating? bne.s DoB_2 ;skip if not move.b #_AOF_DYING,d2 ;else this object is move.b d2,AO_Flags(a0) ;dying... clr.b BAlert(a6) ;end the Baiter alert... * Do this to allow the Baiter to be 'recycled' as it were * so that when it's shot, we can obtain another one... lea BaiterCode(pc),a1 move.l a1,AO_SpecialCode(a0) rts * Here make Baiter move. DoB_2 move.w Anim_XPos(a0),d0 ;current x coord add.w AO_XMove(a0),d0 ;movement value and.w MaxScrPos(a6),d0 ;constrain to screen move.w d0,Anim_XPos(a0) ;replace x coord move.w Anim_YPos(a0),d0 ;change y position add.w AO_YMove(a0),d0 cmp.w #MIN_SY,d0 ;too small? bcc.s DoB_3 ;skip if not move.w #MAX_SY,d0 ;else vertical wrap around DoB_3 cmp.w #MAX_SY,d0 ;too large? bls.s DoB_4 ;skip if not move.w #MIN_SY,d0 ;else vertical wrap around DoB_4 move.w d0,Anim_YPos(a0) ;else set it * Now make Baiter pursue the Defender ship. Accelerate until * the Baiter is sufficiently close, then maintain speed while * hurling missiles... move.l ShipAnim(a6),a1 move.w Anim_XPos(a1),d1 ;ship PLOT position move.w MaxScrPos(a6),d2 move.w d2,d3 lsr.w #1,d3 ;needed later move.w Anim_XPos(a0),d0 ;baiter TRUE position add.w CurrXPos(a6),d0 and.w d2,d0 ;baiter PLOT position sub.w d1,d0 ;baiter xp - ship xp and.w d2,d0 ;normalised cmp.w d3,d0 ;where is Baiter? bhi.s DoB_5 ;skip if right of ship cmp.w #$2000-80,d0 ;really close to ship? bhi.s DoB_8 ;skip if so move.w AO_XMove(a0),d0 ;Baiter speed subq.w #1,d0 ;faster <- direction cmp.w #-BAITERSPD,d0 ;too fast? blt.s DoB_7 ;skip if so move.w d0,AO_XMove(a0) ;else set speed bra.s DoB_7 DoB_5 cmp.w #80,d0 ;really close to ship? bcs.s DoB_9 ;skip if so move.w AO_XMove(a0),d0 ;Baiter speed addq.w #1,d0 ;faster -> direction cmp.w #BAITERSPD,d0 ;too fast? bgt.s DoB_7 ;skip if so move.w d0,AO_XMove(a0) ;else set speed bra.s DoB_7 * Here, if the Baiter is sufficiently close to the Defender, match * its speed to the Defender's speed & start throwing missiles at it * just to make life VERY hard...! DoB_8 move.w CurrXSpeed(a6),d0 ;match speed to Defender move.w d0,AO_XMove(a0) bra.s DoB_7 DoB_9 move.w CurrXSpeed(a6),d0 ;match speed to Defender neg.w d0 move.w d0,AO_XMove(a0) * Now launch a few missiles... DoB_7 bsr XMine rts * Swarmer code. Just set them up as SAMEFRAME and DISABLED anims * and then leave. Also set up the list pointers if they don't * exist. Pod code sets up swarmers when pods burst. SwarmerCode tst.l SwarmerList(a6) ;list pointer set up? bne.s SwrC_3 ;skip if so move.l a0,SwarmerList(a6) ;set up list move.l a0,SwarmerPtr(a6) ;pointers move.l CurrentPlayer(a6),a1 move.l a0,pd_SwarmerList(a1) move.l a0,pd_SwarmerPtr(a1) SwrC_3 move.b #_ANF_SAMEFRAME+_ANF_DISABLED,d0 move.b d0,Anim_Flags(a0) rts * In the code below, keep a careful eye on D1. DoSwarmer move.b AO_Flags(a0),d0 ;check alien status move.b d0,d1 and.b #_AOF_HIT,d0 ;hit by laser? beq.s DoSwarmer_2 ;skip if not eor.b #_AOF_HIT,AO_Flags(a0) and.b #_NANF_SAMEFRAME,Anim_Flags(a0) bra.s DoSwarmer_3 DoSwarmer_2 move.b Anim_Flags(a0),d2 ;check Anim flags and.b #_ANF_SAMEFRAME,d2 ;not animating? bne.s DoSwarmer_1 ;skip if not move.l Anim_CFrame(a0),a1 move.l AnFr_Next(a1),d2 ;done explosion cmp.l d2,a1 ;animating? bne.s DoSwarmer_1 ;skip if not move.b #_AOF_DYING,d2 ;else this object is move.b d2,AO_Flags(a0) ;dying... move.l CurrentPlayer(a6),a1 subq.w #1,pd_Swarmers(a1) rts DoSwarmer_1 and.b #_AOF_ERUPT,d1 ;swarmer erupting? beq.s DoSwarmer_3 ;skip if not subq.w #1,AO_Generic(a0) ;done erupting? bne.s DoSwarmer_3 bsr Random move.l Seed(a6),d0 ;get random no. tst.l d0 spl d1 ;this is -1 if result >=0 smi d2 ;this is -1 if result <0 neg.b d1 ;this is +1 if result >=0 add.b d1,d2 ext.w d2 add.w d2,d2 move.w d2,AO_XMove(a0) tst.w d0 spl d1 ;this is -1 if result >=0 smi d2 ;this is -1 if result <0 neg.b d1 ;this is +1 if result >=0 add.b d1,d2 ext.w d2 add.w d2,d2 move.w d2,AO_YMove(a0) rts DoSwarmer_3 move.w Anim_XPos(a0),d0 ;current x coord add.w AO_XMove(a0),d0 ;movement value and.w MaxScrPos(a6),d0 ;constrain to screen move.w d0,Anim_XPos(a0) ;replace x coord move.w Anim_YPos(a0),d0 ;change y position add.w AO_YMove(a0),d0 cmp.w #MIN_SY,d0 ;too small? bcc.s DoSwr_1 ;skip if not move.w #MAX_SY,d0 ;else vertical wrap around DoSwr_1 cmp.w #MAX_SY,d0 ;too large? bls.s DoSwr_2 ;skip if not move.w #MIN_SY,d0 ;else vertical wrap around DoSwr_2 move.w d0,Anim_YPos(a0) ;else set it bsr SMine ;and make player's life hard... rts * This code initialises the Pods. PodCode bsr Random move.l Seed(a6),d0 ;get random number and.w #$FF,d0 sub.w #$7F,d0 add.w PodBasePos(a6),d0 ;set x position and.w MaxScrPos(a6),d0 move.w d0,Anim_XPos(a0) swap d0 and.w #$7F,d0 add.w #MIN_SY+2,d0 ;create random Y position move.w d0,Anim_YPos(a0) ;save it moveq #1,d0 move.w d0,AO_YMove(a0) moveq #2,d0 move.w d0,AO_XMove(a0) ;pod movement speed=(+4,+1) moveq #10,d0 move.w d0,AO_Generic(a0) ;no of swarmers when split bsr Random ;leave this in! move.l Seed(a6),d0 tst.l d0 bpl.s PodC_1 neg.w AO_XMove(a0) ;negate x & y speeds according PodC_1 tst.w d0 ;to random seed value bpl.s PodC_2 neg.w AO_YMove(a0) PodC_2 lea DoPod(pc),a1 move.l a1,AO_SpecialCode(a0) ;now change PodCode rts * This executed for Pod movement & splitting into Swarmers when * pod is hit by laser bolt... DoPod move.b AO_Flags(a0),d0 ;check alien status move.b d0,d1 and.b #_AOF_HIT,d0 ;hit by laser? beq DoPod_1 ;skip if not (.s) * Here, start spitting out swarmers! Why does this cause VBL * flicker I wonder...it isn't this so look at the swarmer code! move.l SwarmerPtr(a6),a1 ;ptr to Swarmer list... move.l SSIStartup(a6),a2 ;ptr to Startup list... move.w Anim_ID(a1),d0 ;get ID cmp.w #_AL_SWARMER,d0 ;genuine swarmer? bne.s DoPod_3 ;skip if not bsr Random move.l Seed(a6),d0 and.w #$F,d0 ;random 0 to 15 add.w d0,d0 add.w d0,d0 add.w d0,d0 ;*8 for entry size add.w d0,a2 move.w (a2)+,AO_XMove(a1) move.w (a2)+,AO_YMove(a1) move.w (a2)+,AO_Generic(a1) move.b (a2)+,Anim_Flags(a1) move.b (a2)+,AO_Flags(a1) ; or.b #_ANF_DISABLED,Anim_Flags(a1) move.w Anim_XPos(a0),Anim_XPos(a1) move.w Anim_YPos(a0),Anim_YPos(a1) lea DoSwarmer(pc),a2 ; lea DoSwarmer_3(pc),a2 move.l a2,AO_SpecialCode(a1) DoPod_3 move.l Anim_Next(a1),d0 ;get next ptr beq.s DoPod_4 ;none left! move.l d0,SwarmerPtr(a6) ;else save this back move.l CurrentPlayer(a6),a1 move.l d0,pd_SwarmerPtr(a1) DoPod_4 subq.w #1,AO_Generic(a0) ;done them all? beq.s DoPod_7 ;skip if so rts ;else leave now DoPod_7 move.b #_AOF_DYING,d0 ;now this pod is move.b d0,AO_Flags(a0) ;dying... move.l CurrentPlayer(a6),a1 subq.w #1,pd_Pods(a1) rts * This is the quick Pod code that causes no problems... DoPod_1 move.w Anim_XPos(a0),d0 ;change X position add.w AO_XMove(a0),d0 and.w MaxScrPos(a6),d0 ;constrain to screen limits move.w d0,Anim_XPos(a0) move.w Anim_YPos(a0),d0 ;change y position add.w AO_YMove(a0),d0 cmp.w #MIN_SY,d0 ;too small? bcc.s DoPod_5 ;skip if not move.w #MAX_SY,d0 ;else vertical wrap around DoPod_5 cmp.w #MAX_SY,d0 ;too large? bls.s DoPod_6 ;skip if not move.w #MIN_SY,d0 ;else vertical wrap around DoPod_6 move.w d0,Anim_YPos(a0) ;else set it move.l AO_ScanMsk1(a0),d1 ;change scanner not.l d1 not.w d1 ;dot colour for move.l d1,AO_ScanMsk1(a0) ;Pod rts * SetPos(a0) * a0 = ptr to AO_ structure * Initialise starting position of object. * d0 corrupt SetPos bsr Random move.l Seed(a6),d0 ;get random value and.w MaxScrPos(a6),d0 ;create random X position swap d0 and.w #$7F,d0 add.w #MIN_SY+2,d0 ;create random Y position move.w d0,Anim_YPos(a0) ;save it swap d0 move.w d0,Anim_XPos(a0) ;and the X position too rts ;byeee! * Mine/Missile Handling System. * InitMines(a6) * a6 = ptr to main program variables * Initialise the Mine/Missile arrays. * d0-d1/a0-a1 corrupt InitMines move.l MineArray(a6),a0 ;ptr to Mine Structure Array move.l MineFree(a6),a1 ;ptr to Mine Free Array moveq #0,d0 ;initial mine index moveq #_MA_SIZE,d1 ;no. of entries IMin_1 move.b #_MDF_FREE,md_Type(a0) ;set type move.b d0,md_Index(a0) ;set index no. clr.b (a1)+ ;set free entry add.w #md_Sizeof,a0 ;next element subq.w #1,d1 ;done them all? bne.s IMin_1 ;skip if not rts * DoMines(a6) * a6 = ptr to main program variables * Handle the mines/missiles. * d0-d6/a0-a2 corrupt DoMines move.l MineArray(a6),a0 ;ptr to Mine/Missile array moveq #_MA_SIZE,d4 ;no. of entries move.w #9240,d5 ;top of screen limit move.w #29040,d6 ;bottom of screen limit DOM_1 moveq #0,d0 moveq #0,d1 move.b md_Type(a0),d0 ;get entry type bne.s DOM_2 ;skip if not free add.w #md_Sizeof,a0 ;next array entry subq.w #1,d4 ;done them all? bne.s DOM_1 ;back for more if not rts DOM_2 subq.w #1,d0 ;get graphic index add.w d0,d0 ;longword index! add.w d0,d0 lea MineImages(a6),a1 add.w d0,a1 move.l (a1),d0 ;save ptr to image move.l YTable(a6),a1 move.w md_YPos(a0),d1 add.w d1,d1 move.w 0(a1,d1.w),d1 ;get YTable offset swap d1 ;save it ; move.w MaxScrPos(a6),d1 ;get true X plot position ; addq.w #1,d1 ; sub.w md_XPos(a0),d1 move.w md_XPos(a0),d1 ;get X position add.w CurrXPos(a6),d1 ;on screen? and.w MaxScrPos(a6),d1 cmp.w #320,d1 bcc DOM_5 ;skip if not on screen move.w d1,d2 ;copy it and.w #$F,d1 ;shift value lsr.w #4,d2 add.w d2,d2 ;word offset swap d1 add.w d2,d1 ;total offset swap d1 ;swap in shift count * Here : D0 = image ptr, D1 = offset|shift. Create shifted mine image * for plotting. move.l d0,a1 move.l MineBuffer(a6),a2 move.l a2,d2 ;save buffer ptr move.l (a1)+,d3 ;shift N times lsr.l d1,d3 ;for correct move.l d3,(a2)+ ;pixel alignment move.l (a1)+,d3 lsr.l d1,d3 move.l d3,(a2)+ move.l (a1)+,d3 lsr.l d1,d3 move.l d3,(a2)+ move.l d2,a1 ;ptr to shifted mine image move.l RasterWaiting(a6),a2 addq.l #2,a2 clr.w d1 swap d1 cmp.w d5,d1 ;off top of playfield? bcs DOM_5 cmp.w d6,d1 ;off bottom of playfield? bhi DOM_5 add.l d1,a2 ;screen ptr move.l (a1)+,d1 or.l d1,(a2) ;plot 1st line add.w #BP_NEXTLINE,a2 move.l (a1)+,d1 or.l d1,(a2) ;plot 2nd line add.w #BP_NEXTLINE,a2 move.l (a1)+,d1 or.l d1,(a2) ;plot 3rd line * Here, see if we've hit the ship. Note corrections for centre of * ship! Also, check if we have a shield enabled, and if so, the * mines don't have any effect. move.b PwrUpOn(a6),d0 ;check if shield is on and.b #_PU_SHLD,d0 bne.s DOM_6 ;skip check if on! move.w md_XPos(a0),d0 add.w CurrXPos(a6),d0 and.w MaxScrPos(a6),d0 move.w md_YPos(a0),d1 move.l ShipAnim(a6),a1 move.w Anim_XPos(a1),d2 addq.w #7,d2 move.w Anim_YPos(a1),d3 addq.w #4,d3 sub.w d2,d0 ;xmine-xship bpl.s DOM_7 neg.w d0 ;abs(...) DOM_7 sub.w d3,d1 ;ymine-yship bpl.s DOM_8 neg.w d1 ;abs(...) DOM_8 and.w #$FFF8,d0 ;hit ship? bne.s DOM_6 ;no we haven't and.w #$FFFC,d1 ;hit ship? bne.s DOM_6 ;no we haven't move.b #_AOF_HIT,AO_Flags(a1) ;signal hit * Here, after we've plotted, check if we're to do any more & * set this entry as free if not. DOM_6 move.w md_XPos(a0),d0 ;here change X & Y add.w md_XMove(a0),d0 ;position of mine/missile and.w MaxScrPos(a6),d0 move.w d0,md_XPos(a0) move.w md_YPos(a0),d0 add.w md_YMove(a0),d0 and.w MaxScrPos(a6),d0 move.w d0,md_YPos(a0) DOM_4 subq.w #1,md_Count(a0) ;check index bne.s DOM_3 ;still operational DOM_5 moveq #0,d0 move.b md_Index(a0),d0 ;get MineFree index move.l MineFree(a6),a1 clr.b 0(a1,d0.w) ;set it as free clr.b md_Type(a0) ;set _MDF_FREE also DOM_3 add.w #md_Sizeof,a0 ;next entry subq.w #1,d4 ;done them all? bne DOM_1 ;back for more if not rts * StopMines(a6) * a6 = ptr to main program variables * This routine stops all mine/missile activity currently pending * in the MineArray. * d0-d1/a0-a1 corrupt StopMines move.l MineArray(a6),a0 moveq #_MA_SIZE,d0 SMN_1 clr.b md_Type(a0) ;set type to _MDF_FREE moveq #0,d1 move.b md_Index(a0),d1 ;get index into FreeArray move.l MineFree(a6),a1 ;ptr to array clr.b 0(a1,d1.w) ;set as free add.w #md_Sizeof,a0 ;next MineArray entry subq.w #1,d0 ;done them all? bne.s SMN_1 ;back for more if not rts ;and done. * Alien mine/missile launching code. * All of the routines above follow a similar stratagem. First see * if the alien is visible. If not, leave NOW. If visible, see if the * next MineArray entry is free. If not, exit. * Once a free MineArray entry is gotten, do a 'coin-toss' type * calculation (get random number, check if equal to threshold) * to see if this time the alien will launch a missile. If this * is not the case, exit. If so, create the MineArray entry for * the appropriate object. * Landers spit missiles in all directions, as do Mutants & * Baiters. The 'persistence' of these is random (some disappear * quickly, others last long enough to hit you-you don't know * which!). Swarmers spit them out in the same direction as they * are moving across the screen, but in the OPPOSITE vertical * direction to make your escape harder! * Bombers lay mines of random persistence in their path. If you * fly into them, doom time! Some last a VERY long time... * LMine(a0,a6) * a0 = ptr to Lander AO_ structure for caller * a6 = ptr to main program vars * Generate a missile if at all possible, and insert into the * mine/missile list. Called by Lander SpecialCode to shoot a * missile at the Defender ship. * a0 MUST be left untouched! * d0-d2/a1 corrupt LMine move.b Anim_Flags(a0),d0 ;check if on screen and.b #_ANF_NOSHOW,d0 beq.s LMine_1 ;skip if visible rts ;else exit LMine_1 move.l MineFree(a6),a1 ;check if this mine/missile move.w MineIndex(a6),d0 ;slot is free move.w d0,d2 tst.b 0(a1,d0.w) beq.s LMine_2 ;skip if free addq.w #1,d0 ;next missile slot cmp.w #_MA_SIZE,d0 ;array bounds check bcs.s LMine_3 ;skip if within bounds moveq #0,d0 ;else loop back to start LMine_3 move.w d0,MineIndex(a6) ;and set new mine index rts ;exit * Here, we have a free Mine Array slot for our Lander's use. Let the * Lander insert an entry here, and set up for the next mine entry. LMine_2 addq.w #1,d2 ;next missile slot cmp.w #_MA_SIZE,d2 ;array bounds check bcs.s LMine_5 ;skip if within bounds moveq #0,d2 ;else loop back to start LMine_5 move.w d2,MineIndex(a6) ;and set new mine index move.w d0,d1 ;md_ struct is 12 bytes: add.w d0,d0 ;this is a quick x 12 add.w d1,d0 ;to index the correct add.w d0,d0 ;element add.w d0,d0 move.l MineArray(a6),a1 add.w d0,a1 ;point to element * This lot uses the Lander's position & movement data to generate a * Missile. It also uses the Lander's movement plus a random pertur- * bation factor. Uses random number to determine if we are actually * loosing off a missile:should only happen on average once every * 16 calls... bsr Random ;new random number move.w Seed(a6),d0 ;are we doing it? and.w #$F000,d0 beq.s LMine_4 ;skip if so rts LMine_4 move.w Anim_XPos(a0),d0 addq.w #5,d0 move.w d0,md_XPos(a1) move.w Anim_YPos(a0),d0 addq.w #5,d0 move.w d0,md_YPos(a1) move.b #_MDF_MISSILE,md_Type(a1) move.w AO_XMove(a0),d0 move.w Seed(a6),d1 and.w #$0F,d1 sub.w #$07,d1 add.w d1,d0 move.w d0,md_XMove(a1) move.w AO_YMove(a0),d0 move.l Seed(a6),d1 and.w #$0F,d1 sub.w #$07,d1 add.w d1,d0 move.w d0,md_YMove(a1) moveq #10,d0 move.w d0,md_Count(a1) moveq #0,d0 move.b md_Index(a1),d0 move.l MineFree(a6),a1 st 0(a1,d0.w) rts * BMine(a0,a6) * a0 = ptr to AO_ struct for calling Bomber * a6 = ptr to main program variables * Lay a mine. * d0-d2/a1 corrupt BMine move.b Anim_Flags(a0),d0 ;check if on screen and.b #_ANF_NOSHOW,d0 beq.s BMine_1 ;skip if visible rts ;else exit BMine_1 move.l MineFree(a6),a1 ;check if this mine/missile move.w MineIndex(a6),d0 ;slot is free move.w d0,d2 tst.b 0(a1,d0.w) beq.s BMine_2 ;skip if free addq.w #1,d0 ;next missile slot cmp.w #_MA_SIZE,d0 ;array bounds check bcs.s BMine_3 ;skip if within bounds moveq #0,d0 ;else loop back to start BMine_3 move.w d0,MineIndex(a6) ;and set new mine index rts ;exit BMine_2 addq.w #1,d2 ;next missile slot cmp.w #_MA_SIZE,d2 ;array bounds check bcs.s BMine_4 ;skip if within bounds moveq #0,d2 ;else loop back to start BMine_4 move.w d2,MineIndex(a6) ;and set new mine index * Here, we have a free slot in the mine/missile array. Create a mine * & lay it in the path described by the Bomber. move.w d0,d1 ;quick x 12 to index add.w d0,d0 ;into the MineArray add.w d1,d0 add.w d0,d0 add.w d0,d0 move.l MineArray(a6),a1 add.w d0,a1 ;point to free element * Now lay the mine. Note position correction for centre of Bomber. First * determine if we are actually laying, and if so, go do it. bsr Random ;new random number move.w Seed(a6),d0 ;are we doing it? and.w #$F000,d0 beq.s BMine_5 ;skip if so rts BMine_5 move.w Anim_XPos(a0),d0 addq.w #2,d0 move.w Anim_YPos(a0),d1 addq.w #2,d1 move.w d0,md_XPos(a1) ;this position move.w d1,md_YPos(a1) moveq #0,d0 move.l d0,md_XMove(a1) ;no movement move.b #_MDF_MINE,md_Type(a1) move.w Seed(a6),d0 and.w #$0F,d0 addq.w #8,d0 move.w d0,md_Count(a1) ;random duration moveq #0,d0 move.b md_Index(a1),d0 move.l MineFree(a6),a1 st 0(a1,d0.w) rts * SMine(a0,a6) * a0 = ptr to AO_ Struct for calling Swarmer * a6 = ptr to main program variables * Let Swarmer pop a missile into play. Usual rules (see above) * apply. * d0-d2/a1 corrupt SMine move.b Anim_Flags(a0),d0 ;get flags and.b #_ANF_NOSHOW,d0 ;on screen? beq.s SMine_1 ;continue if so rts ;else exit SMine_1 move.l MineFree(a6),a1 ;ptr to free list move.w MineIndex(a6),d0 ;check if this is free move.w d0,d2 tst.b 0(a1,d0.w) ;is it free? beq.s SMine_2 ;continue if so addq.w #1,d0 ;next MineIndex cmp.w #_MA_SIZE,d0 ;out of array bounds? bcs.s SMine_3 ;skip if not moveq #0,d0 ;else start from beginning SMine_3 move.w d0,MineIndex(a6) ;set for next call rts SMine_2 addq.w #1,d2 ;next MineIndex cmp.w #_MA_SIZE,d2 ;for next call-see above bcs.s SMine_4 moveq #0,d2 SMine_4 move.w d2,MineIndex(a6) * Here we've got a free Mine Array slot. Set up the missile. move.w d0,d1 ;quick x 12 again! add.w d0,d0 add.w d1,d0 add.w d0,d0 add.w d0,d0 move.l MineArray(a6),a1 add.w d0,a1 ;point to free entry * Here, determine if we're actually launching a missile and if so, * do it. bsr Random move.w Seed(a6),d0 and.w #$E000,d0 beq.s SMine_5 rts * Note position correction below for centre of Swarmer... SMine_5 move.w Anim_XPos(a0),d0 move.w Anim_YPos(a0),d1 addq.w #2,d0 ;swarmer Centre addq.w #2,d1 move.w AO_XMove(a0),d2 add.w d2,d2 move.w d0,md_XPos(a1) move.w d1,md_YPos(a1) move.w d2,md_XMove(a1) move.w AO_YMove(a0),d2 neg.w d2 move.w d2,md_YMove(a1) move.b #_MDF_MISSILE,md_Type(a1) moveq #12,d0 move.w d0,md_Count(a1) moveq #0,d0 move.b md_Index(a1),d0 move.l MineFree(a6),a1 st 0(a1,d0.w) rts * XMine(a0,a6) * a0 = ptr to Baiter AO_ structure for caller * a6 = ptr to main program vars * Generate a missile if at all possible, and insert into the * mine/missile list. Called by Baiter SpecialCode to shoot a * missile at the Defender ship. * a0 MUST be left untouched! * d0-d2/a1 corrupt XMine move.b Anim_Flags(a0),d0 ;check if on screen and.b #_ANF_NOSHOW,d0 beq.s XMine_1 ;skip if visible rts ;else exit XMine_1 move.l MineFree(a6),a1 ;check if this mine/missile move.w MineIndex(a6),d0 ;slot is free move.w d0,d2 tst.b 0(a1,d0.w) beq.s XMine_2 ;skip if free addq.w #1,d0 ;next missile slot cmp.w #_MA_SIZE,d0 ;array bounds check bcs.s XMine_3 ;skip if within bounds moveq #0,d0 ;else loop back to start XMine_3 move.w d0,MineIndex(a6) ;and set new mine index rts ;exit * Here, we have a free Mine Array slot for our Lander's use. Let the * Lander insert an entry here, and set up for the next mine entry. XMine_2 addq.w #1,d2 ;next missile slot cmp.w #_MA_SIZE,d2 ;array bounds check bcs.s XMine_5 ;skip if within bounds moveq #0,d2 ;else loop back to start XMine_5 move.w d2,MineIndex(a6) ;and set new mine index move.w d0,d1 ;md_ struct is 12 bytes: add.w d0,d0 ;this is a quick x 12 add.w d1,d0 ;to index the correct add.w d0,d0 ;element add.w d0,d0 move.l MineArray(a6),a1 add.w d0,a1 ;point to element * This lot uses the Baiter's position & movement data to generate a * Missile. It also uses the Baiter's movement plus a random pertur- * bation factor. Uses random number to determine if we are actually * loosing off a missile:should only happen on average once every * 8 calls... bsr Random ;new random number move.w Seed(a6),d0 ;are we doing it? and.w #$E000,d0 beq.s XMine_4 ;skip if so rts XMine_4 move.w Anim_XPos(a0),d0 addq.w #5,d0 move.w d0,md_XPos(a1) move.w Anim_YPos(a0),d0 addq.w #5,d0 move.w d0,md_YPos(a1) move.b #_MDF_MISSILE,md_Type(a1) move.w AO_XMove(a0),d0 move.w Seed(a6),d1 and.w #$0F,d1 sub.w #$07,d1 add.w d1,d0 move.w d0,md_XMove(a1) move.w AO_YMove(a0),d0 move.l Seed(a6),d1 and.w #$0F,d1 sub.w #$07,d1 add.w d1,d0 move.w d0,md_YMove(a1) moveq #10,d0 move.w d0,md_Count(a1) moveq #0,d0 move.b md_Index(a1),d0 move.l MineFree(a6),a1 st 0(a1,d0.w) rts * New Laser handling code. This code uses a different FireList structure, * and also uses the 68000 to perform the plotting since it might solve a * few collision problems that I'm having. * The new Laser List is a ring (i.e., list tail joined back to head). * Only uses one pointer entry though. * Needs new fire button handling & collision detection given below! * Needs: rsreset ll_Next rs.l 1 ;ptr to next in list or NULL if last ll_YPos rs.w 1 ;y coord ll_LXPtr rs.l 1 ;LHS x ptr ll_RXPtr rs.l 1 ;LHS y ptr ll_LXPos rs.w 1 ;LHS x coord ll_RXPos rs.w 1 ;RHS x coord ll_LXVal rs.w 1 ;LHS plot word ll_RXVal rs.w 1 ;RHS plot word ll_Type rs.b 1 ;whether L to R or R to L ll_Pad rs.b 1 ll_Sizeof rs.w 0 _LL_SIZE equ 10 * InitLaserList(a6) * a6 = ptr to main program variables * Initialise the Laser list. * d0-d1/a0-a1 corrupt InitLaserList move.l LList(a6),a0 ;ptr to 1st entry move.l a0,LListEntry(a6) ;set 1st entry ptr move.l a0,d0 ;copy of ptr moveq #_LL_SIZE,d1 ;no. to do ILL_1 move.l a0,a1 ;copy ptr add.w #ll_Sizeof,a1 ;ptr to next move.l a1,ll_Next(a0) ;insert ptr subq.w #1,d1 ;done them all? beq.s ILL_2 ;skip if so move.l a1,a0 ;else point to next bra.s ILL_1 ILL_2 move.l d0,ll_Next(a0) ;here close the ring rts * ClearLaserList(a6) * a6 = ptr to main program variables * Clear the Laser List coordinates to prevent re-appearance * of laser shots when attack wave changes etc. * d0-d1/a0 corrupt ClearLaserList move.l LList(a6),a0 ;ptr to Laser List move.l a0,d0 ;copy start ptr moveq #0,d1 ;clear value CLLS_1 move.l d1,ll_LXPos(a0) ;prevent firing move.l ll_Next(a0),a0 ;point to next entry cmp.l d0,a0 ;back to start of list? bne.s CLLS_1 ;back for more if not rts ;else done * MakeLaserList(a6) * a6 = ptr to main program variables * Make LaserList. Create plotting entries, then ripple the * coordinates. * d0-d4/a0-a2 corrupt MakeLaserList move.l YTable(a6),a1 ;keep constant move.l RasterWaiting(a6),a2 ;and this addq.l #2,a2 ;overwide screen! lea RHSLines(a6),a0 move.l a0,d0 ;keep constant lea LHSLines(a6),a0 move.l a0,d1 ;keep constant move.l LList(a6),a0 ;ptr to Laser list MLL_1 move.w ll_YPos(a0),d2 ;get y coord add.w d2,d2 ;word index move.w 0(a1,d2.w),d2 ;get offset move.w ll_LXPos(a0),d3 moveq #0,d4 move.w d3,d4 ;copy it asr.w #4,d4 ;horiz. offset add.w d4,d4 ;WORD offset add.w d2,d4 ;total offset add.l a2,d4 move.l d4,ll_LXPtr(a0) move.w d3,d4 and.w #$0F,d4 ;pixel offset add.w d4,d4 ;WORD index exg d1,a2 ;get LHS words move.w 0(a2,d4.w),d4 ;get plot word move.w d4,ll_LXVal(a0) ;and save it exg d1,a2 ;recover ptr move.w ll_RXPos(a0),d3 moveq #0,d4 move.w d3,d4 ;copy it asr.w #4,d4 ;horiz. offset add.w d4,d4 ;WORD offset add.w d2,d4 ;total offset add.l a2,d4 move.l d4,ll_RXPtr(a0) move.w d3,d4 and.w #$0F,d4 ;pixel offset add.w d4,d4 ;WORD index exg d0,a2 ;get RHS words move.w 0(a2,d4.w),d4 ;get plot word move.w d4,ll_RXVal(a0) ;and save it exg d0,a2 ;recover ptr move.l ll_Next(a0),d2 ;get next ptr cmp.l LList(a6),d2 ;back to start? beq.s MLL_2 ;skip if end of list move.l d2,a0 ;else point ot next bra.s MLL_1 ;and back for more * Come here when we've preprocessed the list for plotting. MLL_2 rts * PlotLaserList(a6) * a6 = ptr to main program variables * Plot Laser List and post-process the coordinates. * d0-d3/a0-a2 corrupt PlotLaserList move.l LList(a6),a0 ;ptr to Laser List moveq #-1,d3 ;constant plot word moveq #0,d0 ;replace coords PLL_1 move.l ll_LXPos(a0),d1 ;plot this one? beq.s PLL_7 ;skip if not move.l ll_LXPtr(a0),a1 ;get LHS and RHS plot ptrs move.l ll_RXPtr(a0),a2 cmp.l a1,a2 ;ptrs equal? bcs.s PLL_8 ;skip if LHS > RHS bne.s PLL_2 ;skip if LHS < RHS move.w ll_LXVal(a0),d2 ;create short laser fire and.w ll_RXVal(a0),d2 ;plot word or.w d2,(a1) ;and plot it bra.s PLL_3 ;and skip now done PLL_2 move.w ll_LXVal(a0),d2 ;get LHS plot word or.w d2,(a1)+ ;and plot it PLL_5 cmp.l a1,a2 ;LHS ptr >= RHS ptr? bls.s PLL_4 ;skip if so or.w d3,(a1)+ ;else plot this word bra.s PLL_5 ;and back for more PLL_4 move.w ll_RXVal(a0),d2 ;get RHS plot word or.w d2,(a1) ;and plot it PLL_3 tst.b ll_Type(a0) ;is it L to R? beq.s PLL_10 ;skip if so * Here, handle coordinate changes for right-to-left laser fire. move.l ll_LXPos(a0),d1 ;get LHS/RHS x coords swap d1 ;get LHS x coord cmp.w #_LLHS,d1 ;LHS >= LHS limit? blt.s PLL_6 ;skip if not sub.w #16,d1 ;else change it move.w d1,ll_LXPos(a0) ;and replace bra.s PLL_7 ;and skip PLL_6 move.w d1,d2 ;get LHS coords swap d1 ;get RHS coords cmp.w d2,d1 ;RHS<=LHS? ble.s PLL_8 ;skip if so sub.w #24,d1 ;else change it move.w d1,ll_RXPos(a0) ;and replace bra.s PLL_7 ;and skip PLL_8 move.l d0,ll_LXPos(a0) ;here zero out entries PLL_7 move.l ll_Next(a0),d1 ;end of list? cmp.l LList(a6),d1 beq.s PLL_9 ;skip if so move.l d1,a0 ;else point to next bra.s PLL_1 ;and go process it PLL_9 rts * Here, handle coordinate changes for left-to-right laser fire. PLL_10 move.l ll_LXPos(a0),d1 ;get LHS/RHS coords cmp.w #_LRHS,d1 ;RHS < RHS limit? bge.s PLL_11 ;skip if not add.w #16,d1 ;else change it move.w d1,ll_RXPos(a0) ;and replace bra.s PLL_7 ;and skip PLL_11 move.w d1,d2 ;get RHS coords swap d1 ;get LHS coords cmp.w d2,d1 ;LHS>=RHS? bge.s PLL_8 ;skip if so add.w #24,d1 ;else change it move.w d1,ll_LXPos(a0) ;and replace bra.s PLL_7 ;and skip * Here goes test Laser lists. XLL ds.b ll_Sizeof*_LL_SIZE even * NewFire(a6) * a6 = ptr to main vars * if fire button pressed, then initialise the fire sequence. * d0-d4/a1 corrupt NewFire tst.b FireLock(a6) ;fire button locked? bne NFire_Done ;exit NOW if so move.l FireKeyPtr(a6),a0 ;get which key/stick move.b (a0),d0 ;get var value and.b FireKeyMsk(a6),d0 ;ensure var masked! cmp.b FireKeyVal(a6),d0 ;correct one? bne NFire_Done ;skip if not NFire_3 move.l LListEntry(a6),a0 ;get LaserList ptr tst.l ll_LXPos(a0) ;list entry free? bne.s NFire_Done ;exit if not! tst.w MoveDir(a6) ;L to R? spl d2 ;set if R to L move.l ShipAnim(a6),a1 move.l Anim_XPos(a1),d0 ;ship's x & y position addq.w #6,d0 ;y=y+6 move.w d0,ll_YPos(a0) ;set entry swap d0 ;now get x tst.b d2 ;L to R? bmi.s NFire_1 ;skip if R to L * Here, ship's direction is L to R. Generate appropriate LaserList values * for a left to right ship. add.w #16,d0 ;left x=ship x+16 move.w d0,d1 add.w #16,d1 ;right x=left x+16 bra.s NFire_2 * Here, ship's direction is R to L, so generate the values appropriate * to this direction. NFire_1 move.w d0,d1 ;right x=ship x sub.w #16,d0 ;left x=right x-16 * Here, set LaserList entry. NFire_2 move.w d0,ll_LXPos(a0) ;LHS x coordinate move.w d1,ll_RXPos(a0) ;RHS x coorfdinate move.b d2,ll_Type(a0) ;LtoR/RtoL indicator st FireLock(a6) ;lock fire button till release move.l ll_Next(a0),a0 move.l a0,LListEntry(a6) bsr MissileOn ;do this if Baiter active NFire_Done rts ;and done * NewCollision(a6) * a6 = ptr to main program variables * Handle object collisions. Collisions of 2 types: * 1) Alien hit by laser : alien dies * 2) Alien hits ship : ship dies * d0-d6/a0-a3 corrupt NewCollision move.l ShipAnim(a6),a2 ;get ship ptr move.w Anim_XPos(a2),d0 ;get ship position move.w Anim_YPos(a2),d1 add.w AO_XOff(a2),d0 ;add centre offsets add.w AO_YOff(a2),d1 move.l CollisionList(a6),a0 ;get list ptr NewC_1 move.l (a0)+,d2 ;object pointer exists? beq NewC_2 ;end of table-leave NOW move.l d2,a1 ;get object ptr move.w Anim_ID(a1),d2 ;here check if special cmp.w #_AL_MISSILE,d2 ;missile? beq.s NewC_1 ;skip check if so cmp.w #_AL_POWERUP,d2 ;power-up? beq.s NewC_1 ;it does its own-skip move.w Anim_XPos(a1),d2 ;get object position move.w Anim_YPos(a1),d3 add.w CurrXPos(a6),d2 ;true scrn pos and.w MaxScrPos(a6),d2 ;constrain to screen! move.w d3,d4 ;copy true Y swap d3 move.w d4,d3 move.l Anim_Frames(a1),a3 add.w AnFr_Rows(a3),d3 ;Y + object size swap d3 * Here check if collision with laser. move.l LList(a6),a3 ;laser list move.l a3,d6 NewC_7 tst.l ll_LXPos(a3) ;laser shot active? beq.s NewC_6 ;get next one if not move.w ll_YPos(a3),d4 ;y pos of laser move.w d4,d5 sub.w d3,d4 ;laser y - alien y = y' bmi.s NewC_6 ;laser above alien-try again swap d3 sub.w d3,d5 ;laser y - alien yy = y'' bpl.s NewC_8 ;laser below alien-try again cmp.w ll_LXPos(a3),d2 ;xlaser RHS? bhi.s NewC_8 ;skip if so or.b #_AOF_HIT,AO_Flags(a1) ;signal hit clr.l ll_LXPos(a3) ;prevent shot reuse bra.s NewC_1 ;and leave NewC_8 swap d3 ;recover coord order NewC_6 move.l ll_Next(a3),a3 ;next entry cmp.l d6,a3 ;done all entries? bne.s NewC_7 ;back for more if not * Here check if collided with ship (unless shield on, in which * case no collision check is performed). move.b PwrUpOn(a6),d4 ;shield on? and.b #_PU_SHLD,d4 bne.s NewC_1 ;skip test if so cmp.w #_AL_BODY,Anim_ID(a1) ;Body object? beq NewC_1 ;omit check if so add.w AO_XOff(a1),d2 ;ship collision and.w MaxScrPos(a6),d2 add.w AO_YOff(a1),d3 ;offsets sub.w d1,d3 bpl.s NewC_3 neg.w d3 ;abs(shipy-alieny) NewC_3 sub.w d0,d2 bpl.s NewC_4 neg.w d2 ;abs(shipx-alienx) NewC_4 cmp.w AO_XDisp(a1),d2 ;abs(x2-x1) < min x separation? bcc NewC_1 ;skip if not cmp.w AO_YDisp(a1),d3 ;abs(y2-y1) < min y separation? bcc NewC_1 ;skip if not or.b #_AOF_HIT,AO_Flags(a2) ;signal ship hit or.b #_AOF_HIT,AO_Flags(a1) ;signal alien hit NewC_2 rts * The following code implements the 'end of landscape' once all Bodies * are dead, and causes all Landers to convert to Mutants. * EndOfWorld(a6) * a6 = ptr to main program variables * Cause the end of the world...for now! * d0 corrupt EndOfWorld move.w #40+1,d0 move.w d0,LSCountDown(a6) ;countdown to Death rts * BlastWorld(a6) * a6 = ptr to main program variables * Create the 'World Explosion' effect. Flash the background colour * randomly to create the effect of the 'end of the world'. * d0/a0 corrupt BlastWorld tst.b NoLand(a6) ;already dead? beq.s BW_2 ;skip if not rts * Here, the 'world' is not yet at an end. BW_2 move.w LSCountDown(a6),d0 ;not counting down? beq.s BW_3 ;skip if we're not subq.w #1,d0 ;else do the end of move.w d0,LSCountDown(a6) ;the world countdown bne.s BW_1 ;skip if not yet ended * Here, the 'world' IS at an end. Signal the fact. st NoLand(a6) ;set no landscape move.l CurrentPlayer(a6),a0 ;and for this st pd_NoLand(a0) ;player for now move.w #0,COLOR00(a5) ;and reset bgnd colour BW_3 rts * Here, flash the background colour depending upon the current * random number. BW_1 lea EXPLSF(pc),a0 ;ptr to byte array move.b 0(a0,d0.w),d0 ;get element sne d0 ;set to -1 if nonzero ext.w d0 ;make word sized and.w #$FFF,d0 ;create colour value move.w d0,COLOR00(a5) ;set colour rts * Explosion screen flash array. Basically, byte=0 for black, 1 for white. * Array = 40 elements long. DON'T set LSCountDown(a6) to more than 40+1 * or else strange things may happen... EXPLSF dc.b 0,0,0,0,0,0,0,1 dc.b 0,0,0,0,0,0,1 dc.b 0,0,0,0,0,1 dc.b 0,0,0,0,1 dc.b 0,0,0,1,0,1,0,1,0,1 dc.b 0,0,0,1 even * Starfield code. rsreset st_Next rs.l 1 ;ptr to next (round robin again) st_XPos rs.w 1 ;actual x coordinate st_YPos rs.w 1 ;is actually screen offset! st_Colour rs.b 1 ;which planes to use st_Pad rs.b 1 ;padding byte for alignment st_Sizeof rs.w 0 _ST_SIZE equ 40 * InitStarField(a6) * a6 = ptr to main program variables * Initialise the Starfield for use. * d0-d1/a0-a1 corrupt InitStarField move.l StarField(a6),a0 ;ptr to Starfield move.l a0,d0 ;copy ptr moveq #_ST_SIZE,d1 ;no. of entries ISF_1 move.l a0,a1 ;copy ptr to this entry add.w #st_Sizeof,a1 ;make ptr to next move.l a1,st_Next(a0) ;create link subq.w #1,d1 ;done them all? beq.s ISF_2 ;skip if so move.l a1,a0 ;else new this = old next bra.s ISF_1 ISF_2 move.l d0,st_Next(a0) ;link to 1st in list rts * NewStarField(a6) * a6 = ptr to main program variables * Make a new Starfield using the initialised StarField list. * d0-d2/a0-a1 corrupt NewStarField move.l StarField(a6),a0 ;ptr to StarField move.l a0,d0 ;copy ptr move.l YTable(a6),a1 ;ptr to Y-Table NSF_1 bsr Random ;make random number move.l Seed(a6),d1 ;get value moveq #0,d2 move.w d1,d2 ;copy this divu #320,d2 ;want it MOD 320 swap d2 ;get remainder move.w d2,st_XPos(a0) swap d1 ;now get Y pos and.w #$7F,d1 ;this lot forces it to add.w #MIN_SY,d1 ;lie in the playu area add.w d1,d1 ;word index move.w 0(a1,d1.w),d1 ;get y-table entry move.w d1,st_YPos(a0) bsr Random ;another random number please move.b Seed(a6),d1 ;get it and.b #$07,d1 ;this is colour bne.s NSF_3 ;skip if not background moveq #1,d1 ;else make it colour 1 NSF_3 rol.b #5,d1 ;see why later! move.b d1,st_Colour(a0) move.l st_Next(a0),d1 ;get next ptr cmp.l d0,d1 ;end of list? beq.s NSF_2 ;skip if so move.l d1,a0 ;else point to next entry bra.s NSF_1 ;and create it NSF_2 rts * ShowStarField(a6) * a6 = ptr to main program variables * Display the starfield, and then update the position of * each star in the starfield. Since we're using the ship * speed divided by 4, it's possible for slow moving ships * to cause no starfield scrolling... * d0-d4/a0-a2 corrupt ShowStarField move.l StarField(a6),a0 ;ptr to StarField list move.l a0,d0 ;copy ptr move.l RasterWaiting(a6),a1 ;screen ptr addq.l #2,a1 ;overwide screen! move.w CurrXSpeed(a6),d4 ;get ship speed ; lsr.w #2,d4 ;divide by 4 lsr.w #1,d4 ;divide by 2 tst.w MoveDir(a6) ;moving from L to R? bmi.s SSF_1 ;skip if so neg.w d4 ;else change speed SSF_1 move.b st_Colour(a0),d1 ;get colour ready moveq #0,d2 move.w st_YPos(a0),d2 move.l a1,a2 ;screen ptr add.l d2,a2 ;+vertical offset move.w st_XPos(a0),d2 ;get x position move.w d2,d3 ;copy it asr.w #4,d3 ;get word offset add.w d3,d3 ;get byte offset add.w d3,a2 ;add to scrn addr moveq #0,d3 ;initial plot value and.w #$0F,d2 ;get pixel bits not.b d2 and.b #$0F,d2 bset d2,d3 ;create set pixel SSF_2 add.b d1,d1 ;use this bitplane? bcc.s SSF_3 ;skip if not or.w d3,(a2) ;else plot pixel SSF_3 add.w #BP_HMOD,a2 ;next bitplane add.b d1,d1 ;use this bitplane? bcc.s SSF_4 ;skip if not or.w d3,(a2) ;else plot pixel SSF_4 add.w #BP_HMOD,a2 ;next bitplane add.b d1,d1 ;use this bitplane? bcc.s SSF_5 ;skip if not or.w d3,(a2) ;else plot pixel SSF_5 move.w st_XPos(a0),d2 ;get x position sub.w d4,d2 ;add on ship speed/4 bpl.s SSF_6 ;skip if >=0 add.w #320,d2 ;else put back on display SSF_6 cmp.w #320,d2 ;off RHS edge? bcs.s SSF_7 ;skip if not sub.w #320,d2 ;else put on LHS edge SSF_7 move.w d2,st_XPos(a0) ;save new X position move.l st_Next(a0),a0 ;point to next entry cmp.l d0,a0 ;back to start of list? bne.s SSF_1 ;back for more if not rts ;else done. * Starfield array XST ds.b st_Sizeof*_ST_SIZE even * DoPowerUp(a6) * a6 = ptr to main program variables * Create the PowerUp left by a dead Lander on Defender Plus. * Also to be left by dead Mutants on land-less levels! * d0-d3/a0-a1 corrupt DoPowerUp tst.b GamePlus(a6) ;playing Defender Plus? bne.s DPU_1 ;skip if so rts ;else leave DPU_1 move.l PuPtr(a6),d0 ;got a PowerUp? bne.s DPU_2 ;skip if so rts ;else leave DPU_2 move.l d0,a0 ;get pointer move.b Anim_Flags(a0),d0 ;check if free for use and.b #_ANF_DISABLED,d0 ;dead object? bne.s DPU_2A ;skip if so rts ;else we'll wait for death... * Here, we've got a free slot for our PowerUp. Decide which one, then * set things up accordingly. DPU_2A bsr Random ;make random number move.w Seed(a6),d1 ;get it and.w #$03,d1 ;this power-up type moveq #0,d2 bset d1,d2 and.b PwrUpEn(a6),d2 ;this one enabled? bne.s DPU_3 ;skip if so rts ;else abort DPU_3 nop ; or.b d2,PwrUpOn(a6) ;signal available move.w d1,d2 add.w d2,d2 ;longword index into add.w d2,d2 ;AnFr ptr array move.w d2,d3 ;copy index lea PuAnFr(a6),a1 ;ptr to AnimFrames move.l 0(a1,d2.w),d2 ;get AnFr pointer move.l d2,Anim_Frames(a0) move.l d2,Anim_CFrame(a0) lea PuRoutines(a6),a1 ;ptr to SpecialCodes move.l 0(a1,d3.w),d3 move.l d3,AO_SpecialCode(a0) ;get this one move.w #_AL_POWERUP,Anim_ID(a0) clr.b AO_Flags(a0) clr.l AO_ScanMsk1(a0) ;no scanner dots move.w #200,d0 ;5 secs worth of feature move.w d0,AO_BCount(a0) ;when power-up picked up move.b #_ANF_SAMEFRAME,Anim_Flags(a0) clr.l PuPtr(a6) ;prevent re-re-use! move.l CurrentPlayer(a6),a1 clr.l pd_PuPtr(a1) move.w #$FF0,COLOR00(a5) ;flash screen! st PuDropped(a6) ;signal PowerUp dropped... rts * The following are SpecialCodes for the Powerups. * NOTE : The DoPowerUp() routine changes the background colour * of the screen to yellow as an indicator that a PowerUp has * been dropped. The SpecialCodes for the PowerUps should reset * the background colour to black once this has happened! * DoTurbo(a0,a6) * a6 = ptr to main program variables * a0 = ptr to AO_ struct for Powerup * Check if user picks up Turbo Thrust powerup. * If so, enable it for 5 secs. * d0-d1/a1 corrupt DoTurbo tst.b PuDropped(a6) ;just dropped? beq.s DTB_0 ;skip if not clr.b PuDropped(a6) move.w #0,COLOR00(a5) ;else reset bgnd colour DTB_0 move.w Anim_XPos(a0),d0 ;true playfield pos add.w CurrXPos(a6),d0 and.w MaxScrPos(a6),d0 ;display pos move.l ShipAnim(a6),a1 ;ship AO_ struct sub.w Anim_XPos(a1),d0 ;pos rel. to ship bpl.s DTB_1 ;skip if >0 neg.w d0 cmp.w #7,d0 ;touched it? bls.s DTB_2 ;skip if so * Here, decrease the life count for the Powerup. If it hits zero, * then kill off the Powerup. DTB_4 subq.w #1,AO_BCount(a0) ;finished with powerup? bne.s DTB_3 ;skip if not move.b #_ANF_DISABLED,d0 move.b d0,Anim_Flags(a0) ;else kill it off DTB_3 rts DTB_1 cmp.w #14,d0 ;touched it? bhi.s DTB_4 ;skip if not DTB_2 move.w Anim_YPos(a0),d0 ;get y position sub.w Anim_YPos(a1),d0 ;relative to ship bpl.s DTB_5 neg.w d0 DTB_5 cmp.w #7,d0 ;touched it? bhi.s DTB_4 ;skip if not * Here, we've touched the Powerup. Now enable Turbo Thrust! DTB_6 move.l CurrentPlayer(a6),a1 move.w #200,d0 move.w d0,TurboCount(a6) move.w d0,pd_Turbo(a1) moveq #_PU_TURBO,d0 move.b PwrUpOn(a6),d1 or.b d0,d1 move.b d1,PwrUpOn(a6) move.b d1,pd_PwrUp(a1) move.b #_ANF_DISABLED,d0 move.b d0,Anim_Flags(a0) st PUVis1(a6) ;allow indicator to show st pd_PUVis1(a1) rts * DoShield(a0,a6) * a6 = ptr to main program variables * a0 = ptr to AO_ struct for Powerup * Check if user picks up Shield powerup. * If so, enable it for 5 secs. * d0-d1/a1 corrupt DoShield tst.b PuDropped(a6) ;just dropped? beq.s DSH_0 ;skip if not clr.b PuDropped(a6) move.w #0,COLOR00(a5) ;else reset bgnd colour DSH_0 move.w Anim_XPos(a0),d0 ;true playfield pos add.w CurrXPos(a6),d0 and.w MaxScrPos(a6),d0 ;display pos move.l ShipAnim(a6),a1 ;ship AO_ struct sub.w Anim_XPos(a1),d0 ;pos rel. to ship bpl.s DSH_1 ;skip if >0 neg.w d0 cmp.w #7,d0 ;touched it? bls.s DSH_2 ;skip if so * Here, decrease the life count for the Powerup. If it hits zero, * then kill off the Powerup. DSH_4 subq.w #1,AO_BCount(a0) ;finished with powerup? bne.s DSH_3 ;skip if not move.b #_ANF_DISABLED,d0 move.b d0,Anim_Flags(a0) ;else kill it off DSH_3 rts DSH_1 cmp.w #14,d0 ;touched it? bhi.s DSH_4 ;skip if not DSH_2 move.w Anim_YPos(a0),d0 ;get y position sub.w Anim_YPos(a1),d0 ;relative to ship bpl.s DSH_5 neg.w d0 DSH_5 cmp.w #7,d0 ;touched it? bhi.s DSH_4 ;skip if not * Here, we've touched the Powerup. Now enable shield! DSH_6 move.l CurrentPlayer(a6),a1 move.w #200,d0 move.w d0,ShieldCount(a6) move.w d0,pd_Shield(a1) moveq #_PU_SHLD,d0 move.b PwrUpOn(a6),d1 or.b d0,d1 move.b d1,PwrUpOn(a6) move.b d1,pd_PwrUp(a1) move.b #_ANF_DISABLED,d0 move.b d0,Anim_Flags(a0) st PUVis2(a6) ;allow indicator to show st pd_PUVis2(a1) rts * DoMissile(a0,a6) * a6 = ptr to main program variables * a0 = ptr to AO_ struct for Powerup * See if user picks up Missile powerup, and if so set things * up for missile appearance when Baiter appears. * d0-d1/a1 corrupt DoMissile tst.b PuDropped(a6) ;just dropped? beq.s DMI_0 ;skip if not clr.b PuDropped(a6) move.w #0,COLOR00(a5) ;else reset bgnd colour DMI_0 move.w Anim_XPos(a0),d0 ;true playfield pos add.w CurrXPos(a6),d0 and.w MaxScrPos(a6),d0 ;display pos move.l ShipAnim(a6),a1 ;ship AO_ struct sub.w Anim_XPos(a1),d0 ;pos rel. to ship bpl.s DMI_1 ;skip if >0 neg.w d0 cmp.w #7,d0 ;touched it? bls.s DMI_2 ;skip if so * Here, decrease the life count for the Powerup. If it hits zero, * then kill off the Powerup. DMI_4 subq.w #1,AO_BCount(a0) ;finished with powerup? bne.s DMI_3 ;skip if not move.b #_ANF_DISABLED,d0 move.b d0,Anim_Flags(a0) ;else kill it off DMI_3 rts DMI_1 cmp.w #14,d0 ;touched it? bhi.s DMI_4 ;skip if not DMI_2 move.w Anim_YPos(a0),d0 ;get y position sub.w Anim_YPos(a1),d0 ;relative to ship bpl.s DMI_5 neg.w d0 DMI_5 cmp.w #7,d0 ;touched it? bhi.s DMI_4 ;skip if not * Here, we've touched the Powerup. Now enable the missile * for when the Baiter is active! DMI_6 move.l CurrentPlayer(a6),a1 moveq #_PU_MISSILE,d0 move.b PwrUpOn(a6),d1 or.b d0,d1 move.b d1,PwrUpOn(a6) move.b d1,pd_PwrUp(a1) move.b #_ANF_DISABLED,d0 move.b d0,Anim_Flags(a0) move.l a0,MsPtr(a6) ;set missile pointer move.l a0,pd_MsPtr(a1) st PUVis3(a6) ;allow indicator to show st pd_PUVis3(a1) addq.w #1,SMCount(a6) ;increase missile count addq.w #1,pd_SMCount(a1) ;for this player rts * DoMystery(a0,a6) * a6 = ptr to main program variables * a0 = ptr to AO_ struct for Powerup * See if user picks up Mystery powerup, and if so pick one of the * other features to activate. * d0-d1/a1 corrupt DoMystery tst.b PuDropped(a6) ;just dropped? beq.s DMY_0 ;skip if not clr.b PuDropped(a6) move.w #0,COLOR00(a5) ;else reset bgnd colour DMY_0 move.w Anim_XPos(a0),d0 ;true playfield pos add.w CurrXPos(a6),d0 and.w MaxScrPos(a6),d0 ;display pos move.l ShipAnim(a6),a1 ;ship AO_ struct sub.w Anim_XPos(a1),d0 ;pos rel. to ship bpl.s DMY_1 ;skip if >0 neg.w d0 cmp.w #7,d0 ;touched it? bls.s DMY_2 ;skip if so * Here, decrease the life count for the Powerup. If it hits zero, * then kill off the Powerup. DMY_4 subq.w #1,AO_BCount(a0) ;finished with powerup? bne.s DMY_3 ;skip if not move.b #_ANF_DISABLED,d0 move.b d0,Anim_Flags(a0) ;else kill it off DMY_3 rts DMY_1 cmp.w #14,d0 ;touched it? bhi.s DMY_4 ;skip if not DMY_2 move.w Anim_YPos(a0),d0 ;get y position sub.w Anim_YPos(a1),d0 ;relative to ship bpl.s DMY_5 neg.w d0 DMY_5 cmp.w #7,d0 ;touched it? bhi.s DMY_4 ;skip if not * Here, we've touched the Powerup. Now pick one of the other three * PowerUps to activate. DMY_6 bsr Random ;make random no. move.w Seed(a6),d0 ;get it and.w #3,d0 ;range = 0 to 3 beq.s DMY_6 ;back if zero subq.w #1,d0 ;now range = 0 to 2 add.w d0,d0 ;longword index add.w d0,d0 lea DMY_7(pc),a1 ;ptr to jumptable move.l 0(a1,d0.w),a1 ;get jumptable entry move.b #_ANF_DISABLED,d0 move.b d0,Anim_Flags(a0) jmp (a1) ;and execute DMY_7 dc.l DTB_6 dc.l DSH_6 dc.l DMI_6 * SetMaxThrust(a6) * a6 = ptr to main program variables * If playing Defender Plus, set maximum thrust to turbo level * if turbo thrust enabled. * d0-d1/a0 corrupt SetMaxThrust tst.b GamePlus(a6) ;playing Defender Plus? bne.s SMT_1 ;skip if so rts SMT_1 move.l CurrentPlayer(a6),a0 move.b PwrUpOn(a6),d0 ;get power-up flags move.b d0,d1 ;copy it and.b #_PU_TURBO,d0 ;turbo thrust on? bne.s SMT_2 ;skip if so SMT_3 moveq #$0F,d0 ;set normal max speed move.w d0,MaxScrSpeed(a6) move.b #_PU_TURBO,d0 not.b d0 and.b d0,d1 move.b d1,PwrUpOn(a6) ;clear turbo flag move.b d1,pd_PwrUp(a0) sf PUVis1(a6) ;kill indicator sf pd_PUVis1(a0) rts SMT_2 move.w TurboCount(a6),d0 ;countdown finished? beq.s SMT_3 ;normal thrust if so subq.w #1,d0 ;count down move.w d0,TurboCount(a6) ;store back move.w d0,pd_Turbo(a0) beq.s SMT_3 ;normal thrust if zero moveq #$1F,d0 ;else turbo max speed move.w d0,MaxScrSpeed(a6) rts * SetShield(a6) * a6 = ptr to main program variables * If playing Defender Plus, handle shield. * d0/d1 corrupt SetShield tst.b GamePlus(a6) ;playing Defender Plus? bne.s SSH_1 ;skip if so rts SSH_1 move.l CurrentPlayer(a6),a0 move.b PwrUpOn(a6),d0 ;get power-up flags move.b d0,d1 ;copy it and.b #_PU_SHLD,d0 ;shield on? bne.s SSH_2 ;skip if so SSH_3 move.b #_PU_SHLD,d0 not.b d0 and.b d0,d1 move.b d1,PwrUpOn(a6) ;clear shield flag move.b d1,pd_PwrUp(a0) sf PUVis2(a6) ;kill indicator sf pd_PUVis2(a0) rts SSH_2 move.w ShieldCount(a6),d0 ;countdown finished? beq.s SSH_3 ;kill shield if so subq.w #1,d0 ;count down move.w d0,ShieldCount(a6) ;store back move.w d0,pd_Shield(a0) beq.s SSH_3 ;no shield if zero rts * MissileOn(a6) * a6 = ptr to main program variables * Launch a missile if Baiter active. * BECAUSE THIS IS CALLED FROM THE FIRE ROUTINE, ASSUME ALL * REGISTERS CORRUPT BEFORE ENTRY, AND HENCE UPON EXIT! MissileOn tst.b BAlert(a6) ;Baiter alert? bne.s MON_1 ;skip if so rts ;else exit now MON_1 move.b PwrUpOn(a6),d0 and.b #_PU_MISSILE,d0 ;missile powerup selected? bne.s MON_1A ;skip if so clr.b BAlert(a6) rts ;else exit now MON_1A move.l MsPtr(a6),d0 ;Missile pointer exists? bne.s MON_1B ;continue if so rts ;else leave NOW... MON_1B move.l d0,a0 ;point to it move.b Anim_Flags(a0),d0 ;check if free for use and.b #_ANF_DISABLED,d0 ;free for use? bne.s MON_1C ;skip if so rts ;else leave now MON_1C move.w SMCount(a6),d0 ;any left? bne.s MON_1D ;skip if so move.l CurrentPlayer(a6),a1 moveq #_PU_MISSILE,d0 not.b d0 and.b d0,PwrUpOn(a6) ;signal no more missiles left and.b d0,pd_PwrUp(a1) sf PUVis3(a6) ;kill indicator sf pd_PUVis3(a1) rts MON_1D subq.w #1,d0 ;1 less missile move.w d0,SMCount(a6) move.l CurrentPlayer(a6),a1 move.w d0,pd_SMCount(a1) move.l MsPtr(a6),a0 ;ptr to Missile AO_ struct move.l ShipAnim(a6),a1 ;ptr to Ship AO_ struct move.w Anim_XPos(a1),d0 ;get ship display x pos sub.w CurrXPos(a6),d0 and.w MaxScrPos(a6),d0 ;get ship playfield pos move.w Anim_YPos(a1),d1 ;get ship y position add.w #16,d1 ;make missile y position cmp.w #196,d1 ;missile too low down? bcs.s MON_2 ;skip if not sub.w #32,d1 ;else put above ship MON_2 move.w d0,Anim_XPos(a0) ;set missile position move.w d1,Anim_YPos(a0) clr.w AO_YMove(a0) ;no vertical movement move.w CurrXSpeed(a6),d0 ;match speed to ship lea MsAnFrs(a6),a2 ;ptr to AnFrs for missile tst.w MoveDir(a6) bmi.s MON_3 neg.w d0 ;and match direction too addq.l #4,a2 ;change AnFr ptrs if reversed MON_3 move.w d0,AO_XMove(a0) move.l (a2),d0 move.l d0,Anim_Frames(a0) move.l d0,Anim_CFrame(a0) moveq #_AL_MISSILE,d0 move.w d0,Anim_ID(a0) moveq #-1,d0 clr.w d0 move.l d0,AO_ScanMsk1(a0) clr.b AO_Flags(a0) clr.b Anim_Flags(a0) lea FlyMissile(pc),a1 move.l a1,AO_SpecialCode(a0) clr.b BAlert(a6) ;prevent re-use rts * FlyMissile(a0,a6) * a6 = ptr to main program variables * a0 = ptr to AO_ struct for missile * Fly the missile. * d0-d1/a1-a2 corrupt FlyMissile move.b AO_Flags(a0),d0 ;missile flags move.b d0,d1 and.b #_AOF_LOCKED,d1 ;locked onto Baiter? bne.s FMS_1 ;skip if locked and.b #_AOF_TRACKED,d0 ;tracking Baiter? bne.s FMS_2 ;skip if tracking * Here, we've just launched the missile. So get the pointer to the * Baiter. Leave now if we can't get it. move.l CurrentPlayer(a6),a1 tst.w SMCount(a6) ;last missile? bne.s FMS_13 ;skip if not moveq #_PU_MISSILE,d0 not.b d0 and.b d0,PwrUpOn(a6) ;signal no more and.b d0,pd_PwrUp(a1) ;missiles! FMS_13 move.l pd_BaiterPtr(a1),d0 bne.s FMS_3 FMS_4 rts * Here, we've got the pointer to the Baiter, so signal that we're * tracking it... FMS_3 move.l d0,AO_KidnapPtr(a0) ;ptr to Baiter moveq #_AOF_TRACKED,d0 ;signal we're move.b d0,AO_Flags(a0) ;tracking it... rts * Here, start tracking Baiter, and if the Y positions match, * we've locked on to it. FMS_2 move.w Anim_XPos(a0),d0 ;move missile in add.w AO_XMove(a0),d0 ;given direction and.w MaxScrPos(a6),d0 move.w d0,Anim_XPos(a0) move.l AO_KidnapPtr(a0),a1 move.w Anim_YPos(a1),d0 ;get Baiter y pos cmp.w Anim_YPos(a0),d0 ;positions match? bne.s FMS_4 ;skip if not moveq #_AOF_LOCKED,d0 ;else signal locked move.b d0,AO_Flags(a0) rts * Come here if the missile has locked onto the Baiter. FMS_1 move.l AO_KidnapPtr(a0),a1 ;match missile Y pos move.w Anim_YPos(a1),d0 ;to tracked Baiter move.w d0,Anim_YPos(a0) move.w Anim_XPos(a0),d0 ;move missile in move.w AO_XMove(a0),d1 ;given direction add.w d1,d0 and.w MaxScrPos(a6),d0 ;normalise pos'n! move.w d0,Anim_XPos(a0) lea MsAnFrs(a6),a2 ;AnimFrame pointers tst.w d1 ;check which direction bpl.s FMS_8 ;we're going in addq.l #4,a2 ;here we're going R to L FMS_8 move.l (a2),d2 ;get frame ptr move.l d2,Anim_Frames(a0) move.l d2,Anim_CFrame(a0) * Coordinates below are PLAYFIELD coordinates, NOT display coordinates! * Check where the Baiter is in relation to the missile. move.w Anim_XPos(a1),d0 sub.w Anim_XPos(a0),d0 ;Baiter x - missile x move.w MaxScrPos(a6),d1 and.w d1,d0 ;normalise! lsr.w #1,d1 cmp.w d1,d0 ;Baiter to left? bcc.s FMS_5 ;skip if so * Here, Baiter is to right of missile, so begin moving * missile to right. cmp.w #40,d0 ;close to Baiter? bhi.s FMS_9 ;skip if not moveq #_AOF_HIT,d0 moveq #_ANF_DISABLED,d1 move.b d0,AO_Flags(a1) ;signal Baiter hit move.b d1,Anim_Flags(a0) ;and kill missile move.l AO_ScanLoc(a0),d0 ;scanner dots? beq.s FMS_10 ;skip if not move.l d0,a1 ;else unplot them move.l AO_ScanBit1(a0),d0 not.l d0 and.l d0,(a1) FMS_10 rts FMS_9 move.w AO_XMove(a0),d0 ;get x movement addq.w #1,d0 ;increase speed to right cmp.w #BAITERSPD+8,d0 ;speed too great? bgt.s FMS_6 ;skip if so move.w d0,AO_XMove(a0) ;else set speed FMS_6 rts * Here, Baiter is to left of missile, so begin moving * missile to left. FMS_5 cmp.w #$2000-40,d0 ;close to Baiter? bcs.s FMS_12 ;skip if not moveq #_AOF_HIT,d0 moveq #_ANF_DISABLED,d1 move.b d0,AO_Flags(a1) ;signal Baiter hit move.b d1,Anim_Flags(a0) ;and kill missile move.l AO_ScanLoc(a0),d0 ;scanner dots? beq.s FMS_11 ;skip if not move.l d0,a1 ;else unplot them move.l AO_ScanBit1(a0),d0 not.l d0 and.l d0,(a1) FMS_11 rts FMS_12 move.w AO_XMove(a0),d0 ;get x movement subq.w #1,d0 ;increase speed to left cmp.w #-(BAITERSPD+8),d0 ;speed too great? blt.s FMS_7 ;skip if so move.w d0,AO_XMove(a0) ;else set speed FMS_7 rts