Routines
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57820: Move upward firing bullet
Used by the routine at MOVE_ALL_UP_BULLETS.
Input
IX points at an upward-firing bullet from UP_BULLETS
MOVE_UP_BULLET 57820 LD A,(IX+2)
57823 CP 255
57825 RET Z Return if bullet is disabled
57826 DEC (IX+0) Move bullet left
57829 LD A,(IX+0)
57832 CP 255
57834 JR Z,DISABLE_UP_BULLET If the bullet is too far left, go to DISABLE_UP_BULLET to disable it
57836 LD A,(59786) Get value at L59786
57839 RRA
57840 JP C,COLLIDE_UP_BULLET_SCENERY If bit 0 was set, skip ahead to COLLIDE_UP_BULLET_SCENERY
57843 DEC (IX+1) Move bullet up
57846 LD A,(IX+1)
57849 CP 2
57851 JR Z,DISABLE_UP_BULLET If the bullet is too far up, go to DISABLE_UP_BULLET
COLLIDE_UP_BULLET_SCENERY 57853 LD A,(IX+0) Get X position of bullet
57856 RRA
57857 AND 7
57859 LD C,A
57860 LD A,(IX+1)
57863 SUB 3
57865 RLA
57866 RLA
57867 AND 120
57869 OR C
57870 LD C,A
57871 LD B,0
57873 LD HL,60237 Point HL at the second column of VISIBLE_TILE_MAP
57876 ADD HL,BC
57877 LD A,(HL) Get tile at bullet's position
57878 CP 127
57880 RET Z Return if bullet did not collide with scenery
DISABLE_UP_BULLET 57881 LD (IX+2),255 Set status to 255 (disabled)
57885 RET
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