;; ======================================================================= ;;
;;. UPBGM -- Update Bad Guy Motion.. Called on a 30Hz tick.. . . . . . . . ;;
;; ======================================================================= ;;
UPBGM. PROC
. . . . PSHR. . R5
. . . . MVII. . #BGMPTBL, R4
. . . . CLRR. . R1
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. Iterate through the motion programs . . . . . . . . . . . . . . ;;
. . . . ;;. R0 -- scratch. . . . . . . . . . . . . . . . . . . . . . . . . ;;
. . . . ;;. R1 -- Slot # for MOB (within group 1). . . . . . . . . . . . . ;;
. . . . ;;. R2 -- Program counter for current record . . . . . . . . . . . ;;
. . . . ;;. R3 -- scratch. . . . . . . . . . . . . . . . . . . . . . . . . ;;
. . . . ;;. R4 -- Pointer to BGMP state tables . . . . . . . . . . . . . . ;;
. . . . ;;. R5 -- scratch. . . . . . . . . . . . . . . . . . . . . . . . . ;;
. . . . ;; --------------------------------------------------------------- ;;
. . . . B . . . @@first_bgmp. . ; skip first INCR R1
@@next_bgmp:
. . . . INCR. . R1. . . . . . . ; next slot #
. . . . CMPI. . #5,. . R1. . . ; Is this the end?
. . . . BGE . . @@done_bgmp . . ; Yes, done.
@@first_bgmp:
. . . . SDBD
. . . . MVI@. . R4,. . R2. . . ; Get program counter
. . . . TSTR. . R2. . . . . . . ; If it's zero, motion program is inactive
. . . . BNEQ. . @@active_bgmp. ; Non-zero, it's active.
. . . . ADDI. . #3,. . R4. . . ; Skip rest of record.
. . . . CMPI. . #BGMPTBL+25, R4 ; Is this the end?
. . . . BLT . . @@next_bgmp . . ; No, do the next one.
. . . . B . . . @@done_bgmp . . ; Yes, done.
@@active_bgmp:
. . . . MOVR. . R4,. . R3
. . . . MVI@. . R4,. . R0. . . ; Get delay counter for this motion program
. . . . ADDI. . #2,. . R4. . . ; point to next record
. . . . DECR. . R0. . . . . . . ; Count down the delay counter.
. . . . MVO@. . R0,. . R3. . . ; Store the updated delay counter
. . . . BPL . . @@next_bgmp. . ; If not expired, go to the next program.
@@expired:
. . . . MVI@. . R2, . . R0. . . ; Get next program word.
. . . . INCR. . R2
. . . . MVO@. . R0, . . R3. . . ; Store out lower byte as delay count.
. . . . XOR@. . R3, . . R0. . . ; Clear delay byte
. . . . SWAP. . R0. . . . . . . ; Extract command byte.
. . . . SUBI. . #64,. . R0. . . ; Less than 64?. It's a motion command.
. . . . BMI . . @@cmd_move. . . ;
. . . . SLL . . R0,. . 1
. . . . ADDR. . R0,. . PC. . . ; Otherwise, vector to the other commands.
. . . . B . . . @@cmd_loopa . . ;. 0 : LOOPA
. . . . B . . . @@cmd_loopb . . ;. 1 : LOOPB
. . . . B . . . @@cmd_jump. . . ;. 2 : JUMP
. . . . B . . . @@cmd_fire. . . ;. 3 : FIREA
. . . . B . . . @@cmd_fire. . . ;. 4 : FIREB
. . . . B . . . @@cmd_fire. . . ;. 5 : FIREC
. . . . B . . . @@cmd_die . . . ;. 6 : DIE
. . . . B . . . @@cmd_attr. . . ;. 7 : ATTR
. . . . B . . . @@cmd_seths . . ;. 8 : SETHS
. . . . B . . . @@cmd_clrhs . . ;. 9 : CLRHS
; . . . B . . . @@cmd_wait. . . ; 10 : WAIT aka. NOP.
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. WAIT/NOP:. Just set the delay counter and go to next command.. ;;
. . . . ;; --------------------------------------------------------------- ;;
@@cmd_wait:
@@finish_cmd:
. . . . SUBI. . #5,. . R4. . . ; Rewind to program pointer in record.
. . . . MVO@. . R2,. . R4. . . ; \.
. . . . SWAP. . R2. . . . . . . ;. |-- Store program counter as double-byte
. . . . MVO@. . R2,. . R4. . . ; /. . data
. . . . ADDI. . #3,. . R4. . . ; point to next record.
. . . . B . . . @@next_bgmp. . ; No, do the next one.
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. LOOPA/LOOPB:. Count down the loop counter.. If it goes -ve, . . ;;
. . . . ;;. we're just starting the loop so initialize it and branch. . . . ;;
. . . . ;;. If it goes 0, the loop is just finishing, so fall through.. . . ;;
. . . . ;;. Otherwise, store updated counter and branch.. . . . . . . . . . ;;
. . . . ;; --------------------------------------------------------------- ;;
@@cmd_loopb:
. . . . INCR. . R3. . . . . . . ; Point to loop counter B
@@cmd_loopa:
. . . . INCR. . R3. . . . . . . ; Point to loop counter A
. . . . MVI@. . R2,. . R0. . . ; Read argument to loop into R0
. . . . INCR. . R2. . . . . . . ;
. . . . MVI@. . R3,. . R5. . . ; read loop counter
. . . . DECR. . R5. . . . . . . ; count it down
. . . . BMI . . @@init_loop . . ; if it goes negative, we need to init it.
. . . . BEQ . . @@done_loop . . ; if it goes to zero, it's expiring
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. +ve case:. Store updated counter and branch.. . . . . . . . . . ;;
. . . . ;; --------------------------------------------------------------- ;;
@@exec_loop:. . . . . . . . . . ; otherwise it was an active loop.
. . . . MVO@. . R5,. . R3. . . ; store updated loop counter
@@loop_jump:
. . . . ANDI. . #$FF,. R0. . . ; execute the jump.
. . . . XORI. . #$80,. R0. . . ;
. . . . SUBI. . #$80,. R0. . . ;
. . . . ADDR. . R0,. . R2. . . ;
. . . . B . . . @@finish_cmd. . ; finish this command.
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. -ve case:. Initialize the loop counter and branch.. . . . . . . ;;
. . . . ;; --------------------------------------------------------------- ;;
@@init_loop:
. . . . SWAP. . R0. . . . . . . ;
. . . . MVO@. . R0,. . R3. . . ; initialize the loop counter.
. . . . SWAP. . R0. . . . . . . ;
. . . . B . . . @@loop_jump
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. Zero case:. Zero out the counter and don't branch.. . . . . . . ;;
. . . . ;; --------------------------------------------------------------- ;;
@@done_loop:
. . . . MVO@. . R5,. . R3. . . ; store updated loop counter
. . . . B . . . @@finish_cmd. . ; and that's it.
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. JUMP:. Just read the argument into the program counter.. . . . ;;
. . . . ;; --------------------------------------------------------------- ;;
@@cmd_jump:
. . . . MVI@. . R2,. . R2
. . . . B . . . @@finish_cmd. . . . . . ; Done.
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. MOVE:. Read the X velocity, Y velocity into SPXYV table.. . . . ;;
. . . . ;; --------------------------------------------------------------- ;;
@@cmd_move:
. . . . MOVR. . R1,. . R5. . . . . . . ;\
. . . . ADDR. . R5,. . R5. . . . . . . ; |-- convert slot number to sprite
. . . . ADDI. . #SPXYV, R5. . . . . . . ;/. . X/Y velocity table pointer
. . . . ADDI. . #@@xvel_tbl + 64, R0. . ; Index into X velocity lookup table
. . . . MOVR. . R0,. . R3
. . . . MVI@. . R3,. . R0. . . . . . . ; Get X velocity from lookup
. . . . MVO@. . R0,. . R5. . . . . . . ; Write it to X vel for this sprite
. . . . ADDI. . #@@yvel_tbl - @@xvel_tbl, R3. . ; Index into Y vel lookup tbl
. . . . MVI@. . R3,. . R0. . . . . . . ; Get Y velocity from lookup
. . . . MVO@. . R0,. . R5. . . . . . . ; Write it to Y vel for this sprite.
. . . . B . . . @@finish_cmd. . . . . . ; Done.
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. FIREA:. Make this bad guy drop a bomb. . . . . . . . . . . . . ;;
. . . . ;;. FIREB:. Make this bad guy fire a crater-maker. . . . . . . . . ;;
. . . . ;;. FIREC:. Make this bad guy shoot horizontally to the left.. . . ;;
. . . . ;; --------------------------------------------------------------- ;;
@@cmd_fire:.
. . . . MVII. . #@@firetype - 6, R3
. . . . ADDR. . R0,. . R3
. . . . MVI@. . R3,. . R0. . . ; read X/Y velocity
. . . . INCR. . R3
. . . . MVI@. . R3,. . R3. . . ; read sprite attribute index
. . . . CALL. . BGFIRE
. . . . B . . . @@finish_cmd
@@firetype:
. . . . DECLE. ((VBIAS + $40) SHL 8) + (VBIAS + $00) ; drop the bomb
. . . . DECLE. SPATBL.b2
. . . . DECLE. ((VBIAS + $40) SHL 8) + (VBIAS + $40) ; drop the crater maker
. . . . DECLE. SPATBL.b1
. . . . DECLE. ((VBIAS + $00) SHL 8) + (VBIAS - $80) ; fire left.
. . . . DECLE. SPATBL.b4
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. DIE:. Time for this guy to die.. . . . . . . . . . . . . . . . ;;
. . . . ;; --------------------------------------------------------------- ;;
@@cmd_die:
. . . . CALL. . BGKILL
. . . . B . . . @@finish_cmd
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. ATTR:. Set the Sprite Attribute for this sprite.. . . . . . . . ;;
. . . . ;; --------------------------------------------------------------- ;;
@@cmd_attr:
. . . . MVI@. . R2, . . R0. . . ; Get attribute
. . . . INCR. . R2
. . . . MOVR. . R1, . . R3. . . ; \
. . . . ADDI. . #SPAT,. R3. . . ;. |-- Store attribute number into slot
. . . . MVO@. . R0, . . R3. . . ; /. . in sprite attribute table.
. . . . B. . . @@finish_cmd
. . . .
. . . . ;; --------------------------------------------------------------- ;;
. . . . ;;. CLRHS:. Set the horizontal-scroll bit for this sprite. . . . . ;;
. . . . ;; --------------------------------------------------------------- ;;
@@cmd_clrhs:
. . . . ;; ---------------------------------------------------------------- ;;
. . . . ;;. SETHS:. Set the horizontal-scroll bit for this sprite. . . . . ;;
. . . . ;; ---------------------------------------------------------------- ;;
@@cmd_seths:
@@do_hs:
. . . . MOVR. . R1, . . R3
. . . . ADDI. . #@@shl_tbl, R3
. . . . MVI@. . R3, . . R3
. . . . MOVR. . R3, . . R0
. . . . COMR. . R3
. . . . AND . . SPHSCR, R3
;;. . . ADCR. . PC
. . . . XORR. . R0, . . R3
. . . . MVO . . R3, . . SPHSCR
. . . . B . . . @@finish_cmd
@@shl_tbl:
. . . . DECLE. 1, 2, 4, 8, 16
. . . .
@@done_bgmp:
. . . . PULR. . PC
@@xvel_tbl:
. . . . DECLE. VBIAS - $20, VBIAS - $40, VBIAS - $60, VBIAS - $7F. ; lf0..lf3
. . . . DECLE. VBIAS + $20, VBIAS + $40, VBIAS + $60, VBIAS + $7F. ; rg0..rg3
. . . . DECLE. VBIAS,. . . VBIAS,. . . VBIAS,. . . VBIAS. . . . ; up0..up3
. . . . DECLE. VBIAS,. . . VBIAS,. . . VBIAS,. . . VBIAS. . . . ; dn0..dn3
. . . . DECLE. VBIAS - $20, VBIAS - $40, VBIAS - $60, VBIAS - $7F. ; lu0..lu3
. . . . DECLE. VBIAS + $20, VBIAS + $40, VBIAS + $60, VBIAS + $7F. ; ru0..ru3
. . . . DECLE. VBIAS - $20, VBIAS - $40, VBIAS - $60, VBIAS - $7F. ; ld0..ld3
. . . . DECLE. VBIAS + $20, VBIAS + $40, VBIAS + $60, VBIAS + $7F. ; rd0..rd3
. . . . DECLE. VBIAS,. . . VBIAS - $08
. . . . ;; directions 33 .. 63 not defined yet.. in no hurry....
@@yvel_tbl:
. . . . DECLE. VBIAS,. . . VBIAS,. . . VBIAS,. . . VBIAS. . . . ; lf0..lf3
. . . . DECLE. VBIAS,. . . VBIAS,. . . VBIAS,. . . VBIAS. . . . ; rg0..rg3
. . . . DECLE. VBIAS - $20, VBIAS - $40, VBIAS - $60, VBIAS - $7F. ; up0..up3
. . . . DECLE. VBIAS + $20, VBIAS + $40, VBIAS + $60, VBIAS + $7F. ; dn0..dn3
. . . . DECLE. VBIAS - $20, VBIAS - $40, VBIAS - $60, VBIAS - $7F. ; lu0..lu3
. . . . DECLE. VBIAS - $20, VBIAS - $40, VBIAS - $60, VBIAS - $7F. ; ru0..ru3
. . . . DECLE. VBIAS + $20, VBIAS + $40, VBIAS + $60, VBIAS + $7F. ; ld0..ld3
. . . . DECLE. VBIAS + $20, VBIAS + $40, VBIAS + $60, VBIAS + $7F. ; rd0..rd3
. . . . DECLE. VBIAS,. . . VBIAS
. . . . ;; directions 33 .. 63 not defined yet.. in no hurry....
. . . . ENDP