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Revs on the BBC Micro

Setup: CallTrackHook

Name: CallTrackHook [Show more] Type: Subroutine Category: Setup Summary: The track file's hook code Deep dive: The track data file format
Context: See this subroutine in context in the source code References: This subroutine is called as follows: * SetupGame calls CallTrackHook
.CallTrackHook BRK \ The SwapCode routine replaces these three bytes with BRK \ the three bytes from just before the trackChecksum in BRK \ the track file, which contain the three bytes of hook \ code for the track \ \ In the default Silverstone track that comes with the \ original version of Revs, the three bytes of hook code \ contain the following: \ \ RTS \ NOP \ NOP \ \ so calling this routine does nothing (see the track \ source in the revs-silverstone.asm file for details) \ \ Other track files, such as those in the Revs 4 Tracks \ expansion pack, contain JMP instructions in their hook \ code, which allows the track authors to hook in entire \ routines that get called when those tracks are loaded