The ModifyGameCode (Part 2 of 3) (Snetterton) subroutine

       Name: ModifyGameCode (Part 2 of 3)                            [Show more]
       Type: Subroutine
   Category: Extra tracks
    Summary: Modify the game code to support the extra track data
    Context: See this subroutine in context in the source code
 References: No direct references to this subroutine in this source file


 The code modifications are done in three parts.

 This is also where the zTrackSegmentO table is built, once the modifications
 have been done. The routine is exactly 40 bytes long, so there's one byte for
 each outer segment z-coordinate.


.mods2

 LDA #&20               \ ?&1248 = &20 (opcode for a JSR instruction)
 STA &1248

 STA &12FB              \ ?&12FB = &20 (opcode for a JSR instruction)

 STA &2538              \ ?&2538 = &20 (opcode for a JSR instruction)

 STA &45CB              \ ?&45CB = &20 (opcode for a JSR instruction)

 LDA #&EA               \ ?&2545 = &EA (opcode for a NOP instruction)
 STA &2545

 LDA #22                \ ?&4F55 = 22 (argument in a CMP #22 instruction)
 STA &4F55

 STA &4F59              \ ?&4F59 = 22 (argument in a CMP #22 instruction)

 LDA #13                \ ?&24EA = 13 (argument in a CMP #13 instruction)
 STA &24EA

 LDA #&A2               \ ?&1FE9 = &A2 (opcode for a LDX # instruction)
 STA &1FE9

 JMP mods3              \ Jump to part 3