Routines
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46274: Fill Debris Slots
Write 17 type-228 slots from World_Slot_1 using the actor X/Y at DE and ROM bytes addressed by RandomNumber.
Input
DE Address of the actor world X and Y
Point HL at the first world slot.
FillDebrisSlots 46274 LD HL,24744 HL=World_Slot_1.
46277 LD BC,1809 Set B to 7 bytes to clear and C to 17 slots.
Point HL' at ROM using RandomNumber as the low byte.
46280 EXX Switch to the shadow registers.
46281 LD A,(24128) Fetch RandomNumber.
46284 LD L,A Copy it into the low byte of HL'.
46285 LD H,0 Clear the high byte of HL'.
46287 EXX Switch back.
Write type 228 and copy the three-byte X/Y seed.
FillDebrisSlots_Loop 46288 PUSH BC Stash the slot counters on the stack.
46289 LD (HL),228 Write type 228.
46291 INC HL Skip the screen-column byte.
46292 INC HL
46293 LD A,(DE) Fetch the low world X.
46294 LD (HL),A Write it.
46295 INC DE Advance the seed pointer.
46296 INC HL Advance the slot pointer.
46297 LD A,(DE) Fetch the high world X.
46298 LD (HL),A Write it.
46299 INC HL Advance the slot pointer.
46300 INC DE Advance the seed pointer.
46301 LD A,(DE) Fetch the Y.
46302 LD (HL),A Write it.
46303 DEC DE Rewind the seed pointer by two bytes.
46304 DEC DE
46305 INC HL Advance to the speed byte.
Take the next ROM byte as the speed.
46306 EXX Switch to the shadow registers.
46307 LD A,(HL) Fetch the next ROM byte from *HL'.
46308 INC HL Advance HL'.
46309 AND A Jump to FillDebrisSlots_PositiveSpeed if it is positive.
46310 JP P,FillDebrisSlots_PositiveSpeed
46313 OR %11111100 Set bits 2-7.
FillDebrisSlots_WriteSpeed 46315 EXX Switch back.
46316 LD (HL),A Write the speed.
46317 INC HL Advance to the thrust byte.
Force the thrust into the range 251-254.
46318 EXX Switch to the shadow registers.
46319 LD A,(HL) Fetch the next ROM byte from *HL'.
46320 INC HL Advance HL'.
46321 AND %00000011 Keep only bits 0-1.
46323 OR %11111100 Set bits 2-7.
46325 SUB 1 Subtract 1.
46327 EXX Switch back.
46328 LD (HL),A Write the thrust.
46329 INC HL Advance to the colour byte.
Colour is bits 0-2 of the next ROM byte (0 and 1 become WHITE), plus BRIGHT.
46330 EXX Switch to the shadow registers.
46331 LD A,(HL) Fetch the next ROM byte from *HL'.
46332 INC HL Advance HL'.
46333 AND %00000111 Keep only bits 0-2.
46335 CP 2 Jump to FillDebrisSlots_SetBright if it is at least 2.
46337 JR NC,FillDebrisSlots_SetBright
46339 LD A,7 A=WHITE.
FillDebrisSlots_SetBright 46341 OR %01000000 Set bit 6.
46343 EXX Switch back.
46344 LD (HL),A Write the colour.
46345 INC HL Skip the flags byte.
46346 INC HL
Clear the next 7 bytes.
FillDebrisSlots_ClearBytes 46347 LD (HL),0 Write 0.
46349 INC HL Advance the slot pointer.
46350 DJNZ FillDebrisSlots_ClearBytes Decrease the counter by one and jump back to FillDebrisSlots_ClearBytes until it is zero.
Write the sprite delay and its reload value, then step to the next slot.
46352 EXX Switch to the shadow registers.
46353 LD A,(HL) Fetch the next ROM byte from *HL'.
46354 INC HL Advance HL'.
46355 AND %00000111 Keep only bits 0-2.
46357 INC A Increase it by one.
46358 EXX Switch back.
46359 LD (HL),A Write the sprite delay.
46360 INC HL Advance the slot pointer.
46361 LD (HL),A Write the same value as the delay reload.
46362 LD A,L Advance HL by 7 to the next slot.
46363 ADD A,7
46365 LD L,A
46366 LD A,H
46367 ADC A,0
46369 LD H,A
Loop until every slot has been written, then initialise the explosion.
46370 POP BC Restore the slot counters from the stack.
46371 DEC C Decrease the remaining slot count by one.
46372 JR NZ,FillDebrisSlots_Loop Jump back to FillDebrisSlots_Loop if there are slots left.
46374 JP InitialiseExplosion_3 Jump to InitialiseExplosion_3.
Positive ROM speeds become 1-4.
FillDebrisSlots_PositiveSpeed 46377 AND %00000011 Keep only bits 0-1.
46379 INC A Increase it by one.
46380 JR FillDebrisSlots_WriteSpeed Jump to FillDebrisSlots_WriteSpeed.
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