Skip to navigation

Elite on the BBC Micro

Start and end: RESET [Electron version]

Name: RESET [Show more] Type: Subroutine Category: Start and end Summary: Reset most variables
Context: See this subroutine in context in the source code Variations: See code variations for this subroutine in the different versions References: This subroutine is called as follows: * ESCAPE calls RESET * TITLE calls RESET * Main flight loop (Part 9 of 16) calls entry point RES4

Reset our ship and various controls, recharge shields and energy, and then fall through into RES2 to reset the stardust and the ship workspace at INWK. In this subroutine, this means zero-filling the following locations: * Pages &9, &A, &B, &C and &D * BETA to BETA+6, which covers the following: * BETA, BET1 - Set pitch to 0 * XC, YC - Set text cursor to (0, 0) * QQ22 - Set hyperspace counters to 0 * ECMA - Turn E.C.M. off It also sets QQ12 to &FF, to indicate we are docked, recharges the shields and energy banks, and then falls through into RES2. Other entry points: RES4 Reset the shields and energy banks, then fall through into RES2 to reset the stardust and the ship workspace at INWK
.RESET JSR ZERO \ Zero-fill pages &9, &A, &B, &C and &D, which clears \ the ship data blocks, the ship line heap, the ship \ slots for the local bubble of universe, and various \ flight and ship status variables LDX #6 \ Set up a counter for zeroing BETA through BETA+6 .SAL3 STA BETA,X \ Zero the X-th byte after BETA DEX \ Decrement the loop counter BPL SAL3 \ Loop back for the next byte to zero STX QQ12 \ X is now negative - i.e. &FF - so this sets QQ12 to \ &FF to indicate we are docked \ We now fall through into RES4 to restore shields and \ energy, and reset the stardust and ship workspace at \ INWK .RES4 LDA #&FF \ Set A to &FF so we can fill up the shields and energy \ bars with a full charge LDX #2 \ We're now going to recharge both shields and the \ energy bank, which live in the three bytes at FSH, \ ASH (FSH+1) and ENERGY (FSH+2), so set a loop counter \ in X for 3 bytes .REL5 STA FSH,X \ Set the X-th byte of FSH to &FF to charge up that \ shield/bank DEX \ Decrement the lopp counter BPL REL5 \ Loop back to REL5 until we have recharged both shields \ and the energy bank \ Fall through into RES2 to reset the stardust and ship \ workspace at INWK