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Elite on the BBC Micro

Maths (Arithmetic): GC2 [Elite-A, Parasite]

Name: GC2 [Show more] Type: Subroutine Category: Maths (Arithmetic) Summary: Calculate (Y X) = (A P) * 4
Context: See this subroutine in context in the source code References: This subroutine is called as follows: * TT151 calls GC2 * TT210 calls entry point price_xy

Calculate the following multiplication of unsigned 16-bit numbers: (Y X) = (A P) * 4 Other entry points: price_xy Set (Y X) = (A P)
.GC2 ASL P \ Set (A P) = (A P) * 4 ROL A ASL P ROL A .price_xy TAY \ Set (Y X) = (A P) LDX P RTS \ Return from the subroutine