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⌂ ∞ ▽ Elite on the 6502

Drawing ships: GetShipBlueprint

[NES version, Bank 7]

       Name: GetShipBlueprint                                        [Show more]
       Type: Subroutine
   Category: Drawing ships
    Summary: Fetch a specified byte from the current ship blueprint

    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * HITCH calls GetShipBlueprint
             * Main flight loop (Part 8 of 16) calls GetShipBlueprint
             * Main flight loop (Part 12 of 16) calls GetShipBlueprint
             * MVEIT (Part 4 of 9) calls GetShipBlueprint
             * NWSHP calls GetShipBlueprint
             * SPIN calls GetShipBlueprint
             * TACTICS (Part 2 of 7) calls GetShipBlueprint
             * TACTICS (Part 4 of 7) calls GetShipBlueprint
             * TACTICS (Part 6 of 7) calls GetShipBlueprint




 Arguments:

   Y                    The offset of the byte to return from the blueprint



 Returns:

   A                    The Y-th byte of the current ship blueprint



.GetShipBlueprint

 LDA currentBank        ; Fetch the number of the ROM bank that is currently
 PHA                    ; paged into memory at $8000 and store it on the stack

 LDA #1                 ; Page ROM bank 1 into memory at $8000
 JSR SetBank

 LDA (XX0),Y            ; Set A to the Y-th byte of the current ship blueprint

                        ; Fall through into ResetBankA to retrieve the bank
                        ; number we stored above and page it back into memory