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Flight: wW

[BBC Micro cassette version]

Name: wW [Show more] Type: Subroutine Category: Flight Summary: Start a hyperspace countdown
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: * Ghy calls wW

Start the hyperspace countdown (for both inter-system hyperspace and the galactic hyperdrive).
.wW LDA #15 \ The hyperspace countdown starts from 15, so set A to \ 15 so we can set the two hyperspace counters STA QQ22+1 \ Set the number in QQ22+1 to A, which is the number \ that's shown on-screen during the hyperspace countdown STA QQ22 \ Set the number in QQ22 to 15, which is the internal \ counter that counts down by 1 each iteration of the \ main game loop, and each time it reaches zero, the \ on-screen counter gets decremented, and QQ22 gets set \ to 5, so setting QQ22 to 15 here makes the first tick \ of the hyperspace counter longer than subsequent ticks TAX \ Print the 8-bit number in X (i.e. 15) at text location JMP ee3 \ (0, 1), padded to 5 digits, so it appears in the top \ left corner of the screen, and return from the \ subroutine using a tail call \.hy5 \ This instruction and the hy5 label are commented out \RTS \ in the original - they can actually be found at the \ end of the jmp routine below, so perhaps this is where \ they were originally, but the authors realised they \ could save a byte by using a tail call instead of an \ RTS?