DEC EV ; Decrement EV, the extra vessels spawning delay, and if BPL MLOOPS ; it is still positive, jump to MLOOPS to stop spawning, ; so we only do the following when the EV counter runs ; down INC EV ; EV is negative, so bump it up again, setting it back ; to 0 LDA TP ; Fetch bits 2 and 3 of TP, which contain the status of AND #%00001100 ; mission 2 CMP #%00001000 ; If bit 3 is set and bit 2 is clear, keep going to BNE nopl ; spawn a Thargoid as we are transporting the plans in ; mission 2 and the Thargoids are trying to stop us, ; otherwise jump to nopl to skip spawning a Thargoid JSR DORND ; Set A and X to random numbers CMP #200 ; If the random number in A < 200 (78% chance), jump to BCC nopl ; nopl to skip spawning a Thargoid .fothg2 JSR GTHG+15 ; Call GTHG+15 to spawn a lone Thargoid, without a ; Thargon companion and with slightly less aggression ; than normal JMP MLOOP ; Jump down to MLOOP to do some end-of-loop tidying and ; restart the main loop .nopl JSR DORND ; Set A and X to random numbers LDY gov ; If the government of this system is 0 (anarchy), jump BEQ LABEL_2 ; straight to LABEL_2 to start spawning pirates or a ; lone bounty hunter LDY JUNK ; Set Y to the number of junk items in our local bubble ; of universe (where junk is asteroids, canisters, ; escape pods and so on) LDX FRIN+2,Y ; The ship slots at FRIN are ordered with the first two ; slots reserved for the planet and sun/space station, ; and then any ships, so if the slot at FRIN+2+Y is not ; empty (i.e. is non-zero), then that means the number ; of non-asteroids in the vicinity is at least 1 BEQ game4 ; So if X = 0, there are no ships in the vicinity, so ; jump to game4 to skip the following and increase the ; chances of spawning CMP #50 ; If the random number in A >= 50 (80% chance), jump to BCS MLOOPS ; MLOOPS to stop spawning (so there's a 25% chance of ; spawning pirates or bounty hunters) .game4 CMP #100 ; If the random number in A >= 100 (61% chance), jump to BCS MLOOPS ; MLOOPS to stop spawning (so there's a 39% chance of ; spawning pirates or bounty hunters) AND #7 ; Reduce the random number in A to the range 0-7, and CMP gov ; if A is less than government of this system, jump BCC MLOOPS ; to MLOOPS to stop spawning (so safer governments with ; larger gov numbers have a greater chance of jumping ; out, which is another way of saying that more ; dangerous systems spawn pirates and bounty hunters ; more often) .LABEL_2 JSR Ze ; Call Ze to initialise INWK to a potentially hostile ; ship, and set A and X to random values ; ; Note that because Ze uses the value of X returned by ; DORND, and X contains the value of A returned by the ; previous call to DORND, this does not set the new ship ; to a totally random location. See the deep dive on ; "Fixing ship positions" for details CMP #100 ; Set the C flag depending on whether the random number ; in A >= 100, for the BCS below AND #15 ; Set A to our random number but in the range 16 to 31 ORA #16 STA INWK+27 ; Give the ship we're about to spawn a speed of between ; 16 and 31 BCS mt1 ; If the random number in A >= 100 (61% chance), jump ; to mt1 to spawn pirates, otherwise keep going to ; spawn a lone bounty hunter or a Thargoid INC EV ; Increase the extra vessels spawning counter, to ; prevent the next attempt to spawn extra vessels AND #3 ; Set A = random number in the range 0-3, which we ; will now use to determine the type of ship ADC #CYL2 ; Add A to #CYL2 (we know the C flag is clear as we ; passed through the BCS above), so A is now one of the ; lone bounty hunter ships, i.e. Cobra Mk III (pirate), ; Asp Mk II, Python (pirate) or Fer-de-lance ; ; Interestingly, this logic means that the Moray, which ; is the ship after the Fer-de-lance in the XX21 table, ; never spawns, as the above logic chooses a blueprint ; number in the range CYL2 to CYL2+3 (i.e. 24 to 27), ; and the Moray is blueprint 28 ; ; No other code spawns the ship with blueprint 28, so ; this means the Moray is never seen in Elite ; ; This is presumably a bug, which could be very easily ; fixed by inserting one of the following instructions ; before the ADC #CYL2 instruction above: ; ; * SEC would change the range to 25 to 28, which ; would cover the Asp Mk II, Python (pirate), ; Fer-de-lance and Moray ; ; * LSR A would set the C flag to a random number to ; give a range of 24 to 28, which would cover the ; Cobra Mk III (pirate), Asp Mk II, Python (pirate), ; Fer-de-lance and Moray ; ; It's hard to know what the authors' original intent ; was, but the second approach makes the Moray and Cobra ; Mk III the rarest choices, with the Asp Mk II, Python ; and Fer-de-Lance being more likely, and as the Moray ; is described in the literature as a rare ship, and the ; Cobra can already be spawned as part of a group of ; pirates (see mt1 below), I tend to favour the LSR A ; solution over the SEC approach TAY ; Copy the new ship type to Y JSR THERE ; Call THERE to see if we are in the Constrictor's ; system in mission 1 BCC NOCON ; If the C flag is clear then we are not in the ; Constrictor's system, so skip to NOCON LDA #%11111001 ; Set the AI flag of this ship so that it has E.C.M., STA INWK+32 ; has a very high aggression level of 28 out of 31, is ; hostile, and has AI enabled - nasty stuff! LDA TP ; Fetch bits 0 and 1 of TP, which contain the status of AND #%00000011 ; mission 1 LSR A ; Shift bit 0 into the C flag BCC NOCON ; If bit 0 is clear, skip to NOCON as mission 1 is not ; in progress ORA MANY+CON ; Bit 0 of A now contains bit 1 of TP, so this will be ; set if we have already completed mission 1, so this OR ; will be non-zero if we have either completed mission ; 1, or there is already a Constrictor in our local ; bubble of universe (in which case MANY+CON will be ; non-zero) BEQ YESCON ; If A = 0 then mission 1 is in progress, we haven't ; completed it yet, and there is no Constrictor in the ; vicinity, so jump to YESCON to spawn the Constrictor .NOCON JSR DORND ; Set A and X to random numbers CMP #200 ; First, set the C flag if X >= 200 (22% chance) ROL A ; Set bit 0 of A to the C flag (i.e. there's a 22% ; chance of this ship having E.C.M.) ORA #%11000000 ; Set bits 6 and 7 of A, so the ship is hostile (bit 6) ; and has AI (bit 7) STA INWK+32 ; Store A in the AI flag of this ship TYA ; Set A to the new ship type in Y EQUB $2C ; Skip the next instruction by turning it into ; $2C $A9 $1F, or BIT $1FA9, which does nothing apart ; from affect the flags .YESCON LDA #CON ; If we jump straight here, we are in the mission 1 ; endgame and it's time to spawn the Constrictor, so ; set A to the Constrictor's type .focoug JSR NWSHP ; Spawn the new ship, whether it's a pirate, Thargoid, ; Cougar or Constrictor .mj1 JMP MLOOP ; Jump down to MLOOP, as we are done spawning ships .fothg LDA K%+6 ; Fetch the z_lo coordinate of the first ship in the K% AND #%00111110 ; block (i.e. the planet) and extract bits 1-5 BNE fothg2 ; If any of bits 1-5 are set (96.8% chance), jump up to ; fothg2 to spawn a Thargoid ; If we get here then we're going to spawn a Cougar, a ; very rare event indeed. How rare? Well, all the ; following have to happen in sequence: ; ; * Main loop iteration = 0 (1 in 256 iterations) ; * Skip asteroid spawning (87% chance) ; * Skip cop spawning (0.4% chance) ; * Skip Thargoid spawning (3.2% chance) ; ; so the chances of spawning a Cougar on any single main ; loop iteration are slim, to say the least LDA #18 ; Give the ship we're about to spawn a speed of 27 STA INWK+27 LDA #%01111001 ; Give it an E.C.M., and make it hostile and pretty STA INWK+32 ; aggressive (though don't give it AI) LDA #COU ; Set the ship type to a Cougar and jump up to focoug BNE focoug ; to spawn it .mt1 AND #3 ; It's time to spawn a group of pirates, so set A to a ; random number in the range 0-3, which will be the ; loop counter for spawning pirates below (so we will ; spawn 1-4 pirates) STA EV ; Delay further spawnings by this number STA XX13 ; Store the number in XX13, the pirate counter .mt3 LDA #%00000100 ; Set bit 2 of the NEWB flags and clear all other bits, STA NEWB ; so the ship we are about to spawn is hostile JSR DORND ; Set A and X to random numbers STA T ; Set T to a random number JSR DORND ; Set A and X to random numbers AND T ; Set A to the AND of two random numbers, so each bit ; has 25% chance of being set which makes the chances ; of a smaller number higher AND #7 ; Reduce A to a random number in the range 0-7, though ; with a bigger chance of a smaller number in this range ADC #PACK ; #PACK is set to #SH3, the ship type for a Sidewinder, ; so this sets our new ship type to one of the pack ; hunters, namely a Sidewinder, Mamba, Krait, Adder, ; Gecko, Cobra Mk I, Worm or Cobra Mk III (pirate) JSR NWSHP ; Try adding a new ship of type A to the local bubble DEC XX13 ; Decrement the pirate counter BPL mt3 ; If we need more pirates, loop back up to mt3, ; otherwise we are done spawning, so fall through into ; the end of the main loop at MLOOPName: Main game loop (Part 4 of 6) [Show more] Type: Subroutine Category: Main loop Summary: Potentially spawn a lone bounty hunter, a Thargoid, or up to four pirates Deep dive: Program flow of the main game loop Ship data blocks Fixing ship positions The elusive CougarContext: See this subroutine in context in the source code References: No direct references to this subroutine in this source file
This section covers the following: * Potentially spawn (35% chance) either a lone bounty hunter (a Cobra Mk III, Asp Mk II, Python or Fer-de-lance), a Thargoid, or a group of up to 4 pirates (a mix of Sidewinders, Mambas, Kraits, Adders, Geckos, Cobras Mk I and III, and Worms) * Also potentially spawn a Constrictor if this is the mission 1 endgame, or Thargoids if mission 2 is in progress
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Configuration variable CON = 31
Ship type for a Constrictor
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Configuration variable COU = 32
Ship type for a Cougar
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Configuration variable CYL2 = 24
Ship type for a Cobra Mk III (pirate)
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Subroutine DORND (category: Maths (Arithmetic))
Generate random numbers
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Workspace K% (category: Workspaces)
Ship data blocks
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Label LABEL_2 is local to this routine
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Entry point MLOOP in subroutine Main game loop (Part 5 of 6) (category: Main loop)
The entry point for the main game loop. This entry point comes after the call to the main flight loop and spawning routines, so it marks the start of the main game loop for when we are docked (as we don't need to call the main flight loop or spawning routines if we aren't in space)
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Label MLOOPS in subroutine Main game loop (Part 3 of 6)
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Label NOCON is local to this routine
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Subroutine NWSHP (category: Universe)
Add a new ship to our local bubble of universe
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Configuration variable PACK = SH3
The first of the eight pack-hunter ships, which tend to spawn in groups. With the default value of PACK the pack-hunters are the Sidewinder, Mamba, Krait, Adder, Gecko, Cobra Mk I, Worm and Cobra Mk III (pirate)
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Subroutine THERE (category: Missions)
Check whether we are in the Constrictor's system in mission 1
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Label YESCON is local to this routine
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Subroutine Ze (category: Universe)
Initialise the INWK workspace to a hostile ship
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Label focoug is local to this routine
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Label fothg2 is local to this routine
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Label game4 is local to this routine
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Label mt1 is local to this routine
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Label mt3 is local to this routine
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Label nopl is local to this routine