;;==========================================================================;; ;; Joe Zbiciak's Space Patrol for Intellivision. ;; ;; Copyright 2007, Joe Zbiciak, intvnut AT gmail.com. ;; ;; http://spatula-city.org/~im14u2c/intv/ ;; ;;==========================================================================;; ;;==========================================================================;; ;; ENGINE1 -- This is the very-time-critical GRAM and STIC register update ;; ;; stuff. We calculate this one frame ahead so that all we do ;; ;; here is a bunch of high speed block copies. ;; ;;==========================================================================;; ENGINE1 PROC ;;------------------------------------------------------------------;; ;; During-vblank stuff. We cycle count as it's a tight fit. When ;; ;; we arrive here, we may have as little as 3500 cycles or so ;; ;; for all of our updates, since we have non-interruptible code ;; ;; elsewhere that will delay interrupts. ;; ;;------------------------------------------------------------------;; MVO R0, $20 ; 11 Enable the display @@1: ;;------------------------------------------------------------------;; ;; Copy over sprite "pseudo registers" from 16-bit RAM. ;; ;;------------------------------------------------------------------;; CLRR R5 ; 6 Point to MOB registers MVI SDATP, R4 ; 10 Point to RAM copy of MOB registers ;---- ; 16 ; 11 (from display enable) ;==== ; 27 REPEAT 24 ; unrolled completely for speed MVI@ R4, R0 ; 8 \_ copy STIC shadow register MVO@ R0, R5 ; 9 / ENDR ;---- ; 408 = 17*24 ; 27 (carried forward) ;==== ; 435 ;;------------------------------------------------------------------;; ;; Record collisions with the buggy and clear its collision reg. ;; ;;------------------------------------------------------------------;; MVII #$0103, R0 ; 8 Magic constant SDBD ; 4 \_ sets carry if any collision CMP@ R5, R0 ; 10 / happens w/ MOB 2..7 RLC R1, 1 ; 6 record this collision in lsb of R0 AND MOBHIT, R1 ; 11 store out the collision flag MVO R1, MOBHIT ; 11 store out the collision flag MVO R0, $18 ; 11 \_ Clear previous collisions. MVO R0, $19 ; 11 / ;---- ; 72 ; 435 (carried forward) ;==== ; 507 ;;------------------------------------------------------------------;; ;; Copy over ground data for scrolling ground and horiz bullet. ;; ;;------------------------------------------------------------------;; MVI GDATA, R0 ; 10 Pointer to ground gfx data MVO R0, GGRAM ; 11 MVII #HBGRAM,R1 ; 8 Pointer to horiz bullet GRAM card SUB HBROW, R1 ; 10 Adjust for pixel row of bullet MVI HBDATA, R0 ; 10 Get bullet pixel MVO@ R0, R1 ; 9 Draw it. ;---- ; 58 ; 507 ;==== ; 565 ;;------------------------------------------------------------------;; ;; Copy over rock/crater data for scrolling rocks, craters. ;; ;;------------------------------------------------------------------;; MVI RPTR, R5 ; 10 Pointer to Rock/Crater gfx data MVII #RGRAM, R4 ; 8 ;---- ; 18 ; 565 ;==== ; 583 REPEAT 12*4 ; unrolled completely for speed MVI@ R5, R0 ; 8 \ MVO@ R0, R4 ; 9 |_ copy over 2 rows of card SWAP R0, 1 ; 6 | MVO@ R0, R4 ; 9 / ENDR ;---- ;1536 total for 12 card (48 iters) ; 583 ;==== ;2119 ;;------------------------------------------------------------------;; ;; Update the wheels on the buggy. ;; ;;------------------------------------------------------------------;; MVI WPTR, R4 ; 10 Pointer to wheel graphic (two words) MVI@ R4, R0 ; 8 Get first word MVO R0, WGRAM ; 11 Row 0 SWAP R0, 1 ; 6 MVO R0, WGRAM+1 ; 11 Row 1 MVI@ R4, R0 ; 8 Get second word MVO R0, WGRAM+3 ; 11 Row 2 SWAP R0, 1 ; 6 MVO R0, WGRAM+4 ; 11 Row 3 ;---- ; 82 ;2119 ;==== ;2201 ;;------------------------------------------------------------------;; ;; Also update the "spinner" bad-guy. ;; ;;------------------------------------------------------------------;; MVI SPINCNT,R5 ; 10 Point to the spinner's frame counter MVII #SGRAM, R4 ; 8 Point to spinner's GRAM entry ADDI #SPIN1, R5 ; 8 Offset into spinner's animation MVI@ R5, R0 ; 8 \ MVO@ R0, R4 ; 9 | SWAP R0, 1 ; 6 | MVO@ R0, R4 ; 9 | MVI@ R5, R0 ; 8 | MVO@ R0, R4 ; 9 | SWAP R0, 1 ; 6 | MVO@ R0, R4 ; 9 |-- Copy over 7 rows of 1 card MVI@ R5, R0 ; 8 | MVO@ R0, R4 ; 9 | SWAP R0, 1 ; 6 | MVO@ R0, R4 ; 9 | MVI@ R5, R0 ; 8 | MVO@ R0, R4 ; 9 | ; SWAP R0, 1 ; - | \__ Last row not needed ; MVO@ R0, R4 ; - / / ;---- ; 139 ;2201 ;==== ;2340 ;;------------------------------------------------------------------;; ;; Copy over mountain data for top or middle mountain, if either. ;; ;; We avoid most conditional code here by hard-coding for 8 ;; ;; cards, and relying on external code to set up our GRAM pointer ;; ;; for us. If there's no mountain update this frame, MPTR == 0. ;; ;;------------------------------------------------------------------;; MVI MPTR, R5 ; 10 Get mountain gfx data pointer TSTR R5 ; 6 Is it NULL? BEQ @@nomtn ; 7 If yes, skip mountain update. MVI MGOFS, R4 ; 10 Get GRAM address for mtn gfx. MVI MGRAM, R2 ; 10 Get GRAM address for mtn gfx. MVII #8, R3 ; 8 ANDR R4, R3 ; 6 MVII #$0030, R3 ; 8 Init circular-addressing mask BEQ @@mloop_e ; 7/9 ;---- ; 72 do odd loop ; 74 do even loop ; @@mloop_o: REPEAT 4 ; unrolled completely for speed MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 0, card 0 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 1, card 0 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 2, card 0 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 3, card 0 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 4, card 0 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 5, card 0 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 6, card 0 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 7, card 0 ANDR R3, R4 ; 6 XORR R2, R4 ; 6 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 0, card 1 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 1, card 1 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 2, card 1 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 3, card 1 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 4, card 1 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 5, card 1 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 6, card 1 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 7, card 1 ENDR ;---- ;1072 = (32*8 + 12) * 4 B @@mloop_done ; 9 ; 72 ;---- ;1153 @@mloop_e: REPEAT 4 ANDR R3, R4 ; 6 XORR R2, R4 ; 6 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 0, card 0 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 1, card 0 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 2, card 0 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 3, card 0 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 4, card 0 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 5, card 0 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 6, card 0 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 7, card 0 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 0, card 1 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 1, card 1 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 2, card 1 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 3, card 1 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 4, card 1 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 5, card 1 MVI@ R5, R0 ; 8 MVO@ R0, R4 ; 9 Row 6, card 1 SWAP R0, 1 ; 6 MVO@ R0, R4 ; 9 Row 7, card 1 ENDR ;---- ;1072 = (32*8 + 12)*4 ; 74 ;---- ;1146 @@mloop_done: ;1153 (Worst case: odd loop) ;2340 (carried forward from above) ;==== ;3493 ; 125 Assumed overhead of reaching ENGINE ;==== ;3618 ;;------------------------------------------------------------------;; ;; Punch line: GRAM is available for ~3796 cycles, which means ;; ;; we can tolerate interrupts disabled for up to ~178 cycles. ;; ;;------------------------------------------------------------------;; @@nomtn: ;;------------------------------------------------------------------;; ;; Do remainder of spinner update. ;; ;;------------------------------------------------------------------;; MVI SPINCNT,R5 ; 10 Point to the spinner's frame counter MOVR R5, R1 ; 6 ANDI #$80, R1 ; 8 ADDI #4, R5 ; 8 Update the frame counter ANDI #31*4, R5 ; 8 Mask away the fractional portion XORR R1, R5 ; 6 MVO R5, SPINCNT ; 11 Store it back out ;---- ; 57 ;3618 ;---- ;3675 ENDP ; falls into remainder of ENGINE1 which is outside the PROC @@foo: ;;------------------------------------------------------------------;; ;; Skip card oriented updates if we're not at normal game screen. ;; ;;------------------------------------------------------------------;; MVI EMODE, R0 ; 10 DECR R0 ; 6 BNEQ E1.skip_card ; 7/9 ;---- ; 23 ;;------------------------------------------------------------------;; ;; Finish constructing current frame's "state of the world." ;; ;;------------------------------------------------------------------;; ICALL upcrd ;1331 Do card-oriented updates. ;;------------------------------------------------------------------;; ;; Before we update the "state of the world", check collisions. ;; ;;------------------------------------------------------------------;; ICALL ckbrc ;1000 Check for buggy/rock/crater collision ICALL uphbp ; 596 Update the horizontal bullet ;---- ;6625 E1.skip_card: ; XXX card-update skip hack for debug screen. ;;------------------------------------------------------------------;; ;; Remainder of engine is not safely reentrant. ;; ;;------------------------------------------------------------------;; DIS ; 4 \ MVII #1, R1 ; 8 | !!Critical Section!! CMP EBSY, R1 ; 10 | Check our "ENGINE IS BUSY" flag, ; |-- and if we're busy, just drop a MVO R1, EBSY ; 11 | frame. :-( Not that I like that. BNEQ E1.not_busy ; 9 / ;---- ; 48 ; 19 ;==== ; 67 ADD FDROP, R1 ; \ If we drop a frame, disable all ; |__ tasks for this frame by just MVO R1, FDROP ; | returning Also, increment our JE MISCISR.1 ; / frame-drop count. (debugging) E1.not_busy: CLRR R1 ; 6 MVO R1, MPTR ; 11 clear MPTR for next time. ;;------------------------------------------------------------------;; ;; Done with very-time-sensitive vertical-blanking stuff. ;; ;; Queue up ENGINE2 and chain return via MISCISR. ;; ;;------------------------------------------------------------------;; ;;@@end: MVI DOENG, R0 ; 10 INCR R0 ; 6 MVO R0, DOENG ; 11 CMP SDATP, R0 ; 10 BNC E1.muxok ; 7/9 CLRR R0 ; 6 E1.muxok MVO R0, MUXOK ; 11 allow muxing again JE MISCISR.1 ; 177 (includes return from ISR cost) ;---- ; 255 ; 67 (carried forward) ;6625 ;==== ;6947 ; ENDP __ ;* ======================================================================== *; ;* This program is free software; you can redistribute it and/or modify *; ;* it under the terms of the GNU General Public License as published by *; ;* the Free Software Foundation; either version 2 of the License, or *; ;* (at your option) any later version. *; ;* *; ;* This program is distributed in the hope that it will be useful, *; ;* but WITHOUT ANY WARRANTY; without even the implied warranty of *; ;* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU *; ;* General Public License for more details. *; ;* *; ;* You should have received a copy of the GNU General Public License *; ;* along with this program; if not, write to the Free Software *; ;* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. *; ;* ======================================================================== *; ;* Copyright (c) 2007, Joseph Zbiciak *; ;* ======================================================================== *;