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Elite on the BBC Micro

Demo: TWIST [6502SP version]

Name: TWIST [Show more] Type: Subroutine Category: Demo Summary: Pitch the current ship by a small angle in a positive direction
Context: See this subroutine in context in the source code References: This subroutine is called as follows: * DEMON calls TWIST * DEMON calls entry point TWIST2

Other entry points: TWIST2 Pitch in the direction given in A
.TWIST2 EQUB &2C \ Skip the next instruction by turning it into \ &2C &A9 &00, or BIT &00A9, which does nothing apart \ from affect the flags .TWIST LDA #0 \ Set A = 0 STA RAT2 \ Set the pitch direction in RAT2 to A LDX #15 \ Rotate (roofv_x, nosev_x) by a small angle (pitch) LDY #9 \ in the direction given in RAT2 JSR MVS5 LDX #17 \ Rotate (roofv_y, nosev_y) by a small angle (pitch) LDY #11 \ in the direction given in RAT2 JSR MVS5 LDX #19 \ Rotate (roofv_z, nosev_z) by a small angle (pitch) LDY #13 \ in the direction given in RAT2 and return from the JMP MVS5 \ subroutine using a tail call