Universe: SOLAR

       Name: SOLAR                                                   [Show more]
       Type: Subroutine
   Category: Universe
    Summary: Set up various aspects of arriving in a new system
  Deep dive: The Trumbles mission
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * PlayDemo calls SOLAR
             * TT18 calls SOLAR


 Halve our legal status, update the missile indicators, and set up data blocks
 and slots for the planet and sun.


.SOLAR

 LDA TRIBBLE            ; If we have no Trumbles in the hold, skip to nobirths
 BEQ nobirths

                        ; If we get here then we have Trumbles in the hold, so
                        ; this is where they breed

 LDA #0                 ; Trumbles eat food during the hyperspace journey, so
 STA QQ20               ; zero the amount of food in the hold

 JSR DORND              ; Take the number of Trumbles from TRIBBLE(1 0), add a
 AND #15                ; random number between 4 and 15, and double the result,
 ADC TRIBBLE            ; storing the resulting number in TRIBBLE(1 0)
 ORA #4                 ;
 ROL A                  ; We start with the low byte
 STA TRIBBLE

 ROL TRIBBLE+1          ; And then do the high byte

 BPL P%+5               ; If bit 7 of the high byte is set, then rotate the high
 ROR TRIBBLE+1          ; byte back to the right, so the number of Trumbles is
                        ; always positive

.nobirths

 LSR FIST               ; Halve our legal status in FIST, making us less bad,
                        ; and moving bit 0 into the C flag (so every time we
                        ; arrive in a new system, our legal status improves a
                        ; bit)

 JSR ZINF               ; Call ZINF to reset the INWK ship workspace, which
                        ; doesn't affect the C flag

 LDA QQ15+1             ; Fetch s0_hi

 AND #%00000011         ; Extract bits 0-1 (which also help to determine the
                        ; economy), which will be between 0 and 3

 ADC #3                 ; Add 3 + C, to get a result between 3 and 7, clearing
                        ; the C flag in the process

 STA INWK+8             ; Store the result in z_sign in byte #6

 LDX QQ15+2             ; Set the C flag if s1_lo >= 128, otherwise clear it
 CPX #128

 ROR A                  ; Halve A and set the sign bit to the C flag, and set
 STA INWK+2             ; x_sign to the result, so this moves the planet to the
                        ; right or left of centre

 ROL A                  ; Set A to x_sign << 1, ready for us to roll in the
                        ; sign bit again for y_sign

 LDX QQ15+3             ; Set the C flag if s1_hi >= 128, otherwise clear it
 CPX #128

 ROR A                  ; Set the sign bit to the C flag and set y_sign to the
 STA INWK+5             ; result, so this moves the planet up or down from the
                        ; centre

 JSR SOS1               ; Call SOS1 to set up the planet's data block and add it
                        ; to FRIN, where it will get put in the first slot as
                        ; it's the first one to be added to our local bubble of
                        ; this new system's universe

 LDA QQ15+3             ; Fetch s1_hi, extract bits 0-2, set bits 0 and 7 and
 AND #%00000111         ; store in z_sign, so the sun is behind us at a distance
 ORA #%10000001         ; of 1 to 7
 STA INWK+8

 LDA QQ15+5             ; Fetch s2_hi, extract bits 0-1 and store in x_sign and
 AND #%00000011         ; y_sign, so the sun is either dead centre in our rear
 STA INWK+2             ; laser crosshairs, or off to the top left by a distance
 STA INWK+1             ; of 1 or 2 when we look out the back

 LDA #0                 ; Set the pitch and roll counters to 0 (no rotation)
 STA INWK+29
 STA INWK+30

 STA FRIN+1             ; Set the second slot in the FRIN table to 0, which
                        ; sets this slot to empty, so when we call NWSHP below
                        ; the new sun that gets created will go into FRIN+1

 STA SSPR               ; Set the "space station present" flag to 0, as we are
                        ; no longer in the space station's safe zone

 LDA #129               ; Set A = 129, the ship type for the sun

 JSR NWSHP              ; Call NWSHP to set up the sun's data block and add it
                        ; to FRIN, where it will get put in the second slot as
                        ; it's the second one to be added to our local bubble
                        ; of this new system's universe