.MLOOP LDA #%00000001 \ Set 6522 System VIA interrupt enable register IER STA VIA+&4E \ (SHEILA &4E) bit 1 (i.e. disable the CA2 interrupt, \ which comes from the keyboard) LDX #&FF \ Set the stack pointer to &01FF, which is the standard TXS \ location for the 6502 stack, so this instruction \ effectively resets the stack LDX GNTMP \ If the laser temperature in GNTMP is non-zero, BEQ EE20 \ decrement it (i.e. cool it down a bit) DEC GNTMP .EE20 JSR DIALS \ Call DIALS to update the dashboard LDA QQ11 \ If this is a space view, skip the following four BEQ P%+11 \ instructions (i.e. jump to JSR TT17 below) AND PATG \ If PATG = &FF (author names are shown on start-up) LSR A \ and bit 0 of QQ11 is 1 (the current view is type 1), BCS P%+5 \ then skip the following instruction JSR DELAY-5 \ Wait for 8/50 of a second (0.16 seconds), to slow the \ main loop down a bit JSR TT17 \ Scan the keyboard for the cursor keys or joystick, \ returning the cursor's delta values in X and Y and \ the key pressed in AName: Main game loop (Part 5 of 6) [Show more] Type: Subroutine Category: Main loop Summary: Cool down lasers, make calls to update the dashboard Deep dive: Program flow of the main game loop The dashboard indicatorsContext: 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: * Main game loop (Part 2 of 6) calls via MLOOP * Main game loop (Part 3 of 6) calls via MLOOP * Main game loop (Part 4 of 6) calls via MLOOP * Main game loop (Part 6 of 6) calls via MLOOP
This is the first half of the minimal game loop, which we iterate when we are docked. This section covers the following: * Cool down lasers * Make calls to update the dashboard
Other entry points: MLOOP 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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Subroutine DIALS (Part 1 of 4) (category: Dashboard)
Update the dashboard: speed indicator
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Label EE20 is local to this routine
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Subroutine TT17 (category: Keyboard)
Scan the keyboard for cursor key or joystick movement
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Configuration variable VIA = &FE00
Memory-mapped space for accessing internal hardware, such as the video ULA, 6845 CRTC and 6522 VIAs (also known as SHEILA)