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Elite on the BBC Micro and NES

Maths (Geometry): SCALEY

[BBC Master version]

Name: SCALEY [Show more] Type: Subroutine Category: Maths (Geometry) Summary: Scale the y-coordinate in A
Context: See this subroutine in context in the source code References: This subroutine is called as follows: * TT103 calls SCALEY * TT14 calls SCALEY * TT22 calls SCALEY

This routine (and the related SCALEY2 and SCALEX routines) are called from various places in the code to scale the value in A. This scaling can be changed by changing these routines (for example, by changing an RTS to an LSR A). This code is left over from the conversion to other platforms, where the scale factor might need to be different. The original source contains the comment "SCALE Scans by 3/4 to fit in".
.SCALEY LSR A \ Halve the value in A