Skip to navigation

⌂ ∞ ▽ Elite on the BBC Micro and NES

Version analysis of MLS2

This code appears in the following versions (click to see it in the source code):

Code variations between these versions are shown below.

       Name: MLS2
       Type: Subroutine
   Category: Maths (Arithmetic)
    Summary: Calculate (S R) = XX(1 0) and (A P) = A * ALP1



 Calculate the following:

   (S R) = XX(1 0)

   (A P) = A * ALP1

 where ALP1 is the magnitude of the current roll angle alpha, in the range
 0-31.



.MLS2

 LDX XX                 \ Set (S R) = XX(1 0), starting with the low bytes
 STX R

 LDX XX+1               \ And then doing the high bytes
 STX S

Code variation 1 of 1Other (e.g. bug fix, optimisation)

There's an extra bit of code in the disc version of the MLS2 routine that has no effect.

This variation is blank in the Cassette, Disc (flight), 6502 Second Processor, Master and Electron versions.

Docked
 LDX ALP1               \ This repeats the first two instructions of MLS1, which
 STX P                  \ is presumably unintentional (though it has no effect)

                        \ Fall through into MLS1 to calculate (A P) = A * ALP1