44 lines
1.8 KiB
NASM
44 lines
1.8 KiB
NASM
;this is for making BG2 disappear when pressing X+R and having the book of mudora (modified parallel worlds x button secret), i use bank 0x3C for the whole code
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;WRITTEN: by XaserLE
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;THANKS TO: -MathOnNapkins' Zelda Doc's
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; -wiiqwertyuiop for his Zelda Disassembly
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; Layer Flags: xxxsabcd (i count BG from 1 to 4 - MathOnNapkins RAM-Map counts from 0 to 3)
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; s - Sprite layer enabled
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; a - BG4 enabled
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; b - BG3 enabled
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; c - BG2 enabled
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; d - (BG1 disabled) --> only works properly if the room uses the feature "BG2 on Top"
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header
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lorom
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ORG $0288FD ; go to the code that branches behind the dungeon map load if player didn't press X
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BRA $1C ; make it always branch, so map isn't loaded anymore
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ORG $068365 ; go to an originally JSL that is executed every frame
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JSL $3CA600 ; overwrite it (originally JSL $099F91)
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ORG $3CA600 ; go to expanded space to write our routine (keep EveryFrame.asm in mind for the right adresses)
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LDA $1B ; load data that tells us whether we are in a building or not
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AND #$01 ; are we in a building?
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BEQ END_XBUTTONSECRET ; if not, don't use the x-button-secret
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;BG2 disable on pressing R
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LDA $7EF34D ; load book of mudora slot
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CMP #$01 ; do we have the moon pearl?
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BNE $0F ; if not, go to enable BG2
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LDA $F2 ; load unfiltered joypad 1 register (AXLR|????)
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AND #$50 ; delete all bits except those for X and R
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SEC ; set carry for the following subtraction
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SBC #$50 ; X+R button pressed? (if yes, zero flag is set)
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BNE $06 ; if not, go to enable BG2
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LDA $1C ; load layer flags
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AND #$FD ; disable BG2 (0xFD = 11111101)
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BRA $04 ; go to store layer flags
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LDA $1C ; load layer flags
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ORA #$02 ; enable BG2 (0x02 = 00000010)
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STA $1C ; store layer flags
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END_XBUTTONSECRET:
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JSL $099F91 ; at least execute original code
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RTL |