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⌂ ∞ Lander on the Acorn Archimedes

Maths (Geometry): TransposeRotationMatrix

       Name: TransposeRotationMatrix                                 [Show more]
       Type: Subroutine
   Category: Maths (Geometry)
    Summary: An unused routine that transposes the rotation matrix
  Deep dive: Unused code in Lander

    Context: See this subroutine in context in the source code
 References: No direct references to this subroutine in this source file




.TransposeRotationMatrix

 ADD     R2, R11, #rotationMatrix   \ Set R2 to the address of the rotation
                                    \ matrix

 LDR     R0, [R2, #4]               \ Transpose it by swapping coordinates on
 LDR     R1, [R2, #12]              \ either side of the diagonal from the
 STR     R0, [R2, #12]              \ top-left to bottom-right
 STR     R1, [R2, #4]               \
 LDR     R0, [R2, #8]               \   [ x1 x2 x3 ]      [ x1 y1 z1 ]
 LDR     R1, [R2, #24]              \   [ y1 y2 y3 ]  ->  [ x2 y2 z2 ]
 STR     R0, [R2, #24]              \   [ z1 z2 z3 ]      [ x3 y3 z3 ]
 STR     R1, [R2, #8]               \
 LDR     R0, [R2, #20]              \ This converts the rotation matrix into the
 LDR     R1, [R2, #28]              \ inverse rotation
 STR     R0, [R2, #28]
 STR     R1, [R2, #20]

 MOV     PC, R14                    \ Return from the subroutine