Routines
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DAB7: Throw the last thing taken up
Used by the routine at UPDATE_KNIGHT.
Fire throws what the knight took up last: the carried things (CARRIED) are searched from the eleventh back. An antibody (thing 5-8) goes into a free antibody record (ANTIBODIES) as graphic 80, 84, 88 or 92; with both in use, the record THROW_TOGGLE points at is ended instead if it is still an antibody in flight, and the throw waits for the next press. An object (thing 1-4) goes into its own record, record 4 minus the thing (so the pairs of OBJECT_FLIGHT hold), as graphic 8-11. Either way the thrown thing is a copy of the legs' record -- his place, facing and flags -- given speed 12, half-size 16 and a drawing offset; the thing's place on the panel is redrawn empty, and the throw's sound plays. Two turns must pass before the next throw.
Input
E The controls (bit 3 fire)
KNIGHT_THROWS DAB7 LD HL,FIRE_DELAY Still waiting after the last throw: count down
DABA LD A,(HL)
DABB AND A
DABC JR Z,KNIGHT_THROWS_0
DABE DEC (HL)
DABF RET
KNIGHT_THROWS_0 DAC0 BIT 3,E Fire?
DAC2 RET Z
DAC3 LD HL,CARRIED_LAST Find the last thing carried; B: its place plus one
DAC6 LD B,$0B
KNIGHT_THROWS_1 DAC8 LD A,(HL)
DAC9 AND A
DACA JR NZ,KNIGHT_THROWS_2
DACC DEC HL
DACD DJNZ KNIGHT_THROWS_1
DACF RET
KNIGHT_THROWS_2 DAD0 CP $05 Things 1-4 are the objects
DAD2 JR C,KNIGHT_THROWS_6
DAD4 LD IY,ANTIBODIES An antibody: a free antibody record?
DAD8 LD DE,$0010
DADB LD C,$02
KNIGHT_THROWS_3 DADD LD A,(IY+$00)
DAE0 AND A
DAE1 JR Z,KNIGHT_THROWS_4
DAE3 ADD IY,DE
DAE5 DEC C
DAE6 JR NZ,KNIGHT_THROWS_3
DAE8 LD HL,ANTIBODIES Both in use: the one THROW_TOGGLE points at...
DAEB LD A,(THROW_TOGGLE)
DAEE AND $10
DAF0 LD C,A
DAF1 LD B,$00
DAF3 ADD HL,BC
DAF4 LD A,(HL) ...if it is still flying (graphic 80-95)...
DAF5 SUB $50
DAF7 CP $10
DAF9 RET NC
DAFA LD (HL),$0C ...vanishes; the thing is kept for the next press
DAFC RET
KNIGHT_THROWS_4 DAFD LD A,(THROW_TOGGLE) Flip which record a full pair loses next
DB00 XOR $10
DB02 LD (THROW_TOGGLE),A
DB05 PUSH BC Take the thing out of its place
DB06 PUSH HL
DB07 LD A,(HL)
DB08 LD (HL),$00
DB0A LD HL,KNIGHT The antibody record: a copy of the legs'
DB0D PUSH IY
DB0F POP DE
DB10 LD BC,$0010
DB13 LDIR
DB15 ADD A,A Graphic 4 times the thing plus 60: 80, 84, 88, 92
DB16 ADD A,A
DB17 ADD A,$3C
KNIGHT_THROWS_5 DB19 LD (IY+$00),A The graphic; shared with the objects
DB1C LD (IY+$05),$0C Speed 12
DB20 LD A,$10 Half-size 16 each way
DB22 LD (IY+$08),A
DB25 LD (IY+$09),A
DB28 LD (IY+$0C),$F8 The drawing offset
DB2C LD (IY+$0D),$04
DB30 LD A,$02 Two turns before the next throw
DB32 LD (FIRE_DELAY),A
DB35 POP HL Redraw the place it was carried in, now empty (PICK_UP_THING counts the places from the other end)
DB36 POP BC
DB37 LD A,B
DB38 NEG
DB3A ADD A,$0C
DB3C LD B,A
DB3D CALL DRAW_CARRIED
DB40 JP FIRE_SOUND The throw's sound
KNIGHT_THROWS_6 DB43 PUSH BC An object: take it out of its place
DB44 PUSH HL
DB45 PUSH AF
DB46 LD (HL),$00
DB48 NEG Its own record: OBJECTS plus 16 times (4 minus the thing)
DB4A ADD A,$04
DB4C ADD A,A
DB4D ADD A,A
DB4E ADD A,A
DB4F ADD A,A
DB50 LD HL,OBJECTS
DB53 CALL ADD_HL_A
DB56 PUSH HL A copy of the legs' record
DB57 PUSH HL
DB58 POP IY
DB5A POP DE
DB5B LD HL,KNIGHT
DB5E LD BC,$0010
DB61 LDIR
DB63 POP AF Graphic the thing plus 7: 8-11, and on as for an antibody
DB64 ADD A,$07
DB66 JR KNIGHT_THROWS_5
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