156 lines
4.7 KiB
NASM
156 lines
4.7 KiB
NASM
;--------------------------------------------------------------------------------
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WriteSaveChecksumAndBackup:
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LDX.w #$0000 : TXA : - ; Checksum first $04FE bytes
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CLC : ADC.l SaveDataWRAM, X
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INX #2
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CPX.w #$04FE : BNE -
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LDX.w #$0000 : - ; Checksum extended save data
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CLC : ADC.l ExtendedFileNameWRAM, X
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INX #2
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CPX.w #$0FFE : BNE -
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STA.b Scrap00
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LDA.w #$5A5A
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SEC : SBC.b Scrap00
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STA.l InverseChecksumSRAM
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PHB
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LDA.w #$14FF ; \
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LDX.w #CartridgeSRAM ; | Copies $1500 bytes from beginning of cart SRAM to
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LDY.w #SaveBackupSRAM ; | $704000
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MVN !SRAMBank, !SRAMBank ; /
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PLB
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TDC
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TAX
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RTL
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;--------------------------------------------------------------------------------
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ValidateSRAM:
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REP #$30
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LDX.w #$0000 : TXA : - ; Checksum first $04FE bytes
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CLC : ADC.l CartridgeSRAM, X
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INX #2
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CPX.w #$04FE : BNE -
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LDX.w #$0000 : - ; Checksum extended save data
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CLC : ADC.l ExtendedFileNameSRAM, X
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INX #2
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CPX.w #$0FFE : BNE -
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STA.b Scrap00
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LDA.w #$5A5A
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SEC : SBC.b Scrap00
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CMP.l InverseChecksumSRAM : BEQ .goodchecksum
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LDX.w #$0000 : TXA : - ; Do the same for the backup save
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CLC : ADC.l SaveBackupSRAM, X
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INX #2
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CPX.w #$04FE : BNE -
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LDX.w #$0000 : -
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CLC : ADC.l SaveBackupSRAM+$500, X
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INX #2
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CPX.w #$0FFE : BNE -
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STA.b Scrap00
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LDA.w #$5A5A
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SEC : SBC.b Scrap00
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CMP.l SaveBackupSRAM+$4FE : BEQ +
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TDC : STA.l FileValiditySRAM ; Delete save by way of zeroing validity marker
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BRA .goodchecksum : +
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PHB
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LDA.w #$14FF ; \
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LDX.w #SaveBackupSRAM ; | Copies $1500 bytes from backup on cart SRAM to
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LDY.w #CartridgeSRAM ; | main save location at $700000
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MVN !SRAMBank, !SRAMBank ; /
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PLB
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.goodchecksum
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LDX.w #$00FE : - ; includes prize pack reset after save and quit
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STZ.w $0D00, X
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STZ.w $0E00, X
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STZ.w $0F00, X
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DEX #2
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BPL -
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SEP #$30
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RTL
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;--------------------------------------------------------------------------------
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ClearExtendedSaveFile:
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STA.l $700400, X ; what we wrote over
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STA.l $700500, X
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STA.l $700600, X
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STA.l $700700, X
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STA.l $700800, X
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STA.l $700900, X
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STA.l $700A00, X
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STA.l $700B00, X
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STA.l $700C00, X
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STA.l $700D00, X
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STA.l $700E00, X
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STA.l $700F00, X
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STA.l $701000, X
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STA.l $701100, X
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STA.l $701200, X
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STA.l $701300, X
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STA.l $701400, X
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; Clear backup save
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STA.l $704000, X
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STA.l $704100, X
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STA.l $704200, X
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STA.l $704300, X
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STA.l $704400, X
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STA.l $704500, X
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STA.l $704600, X
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STA.l $704700, X
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STA.l $704800, X
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STA.l $704900, X
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STA.l $704A00, X
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STA.l $704B00, X
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STA.l $704C00, X
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STA.l $704D00, X
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STA.l $704E00, X
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STA.l $704F00, X
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STA.l $705000, X
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STA.l $705100, X
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STA.l $705200, X
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STA.l $705300, X
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STA.l $705400, X
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RTL
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;--------------------------------------------------------------------------------
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ClearExtendedWRAMSaveFile:
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STA.l $7EF400, X ; what we wrote over
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STA.l $7F6000, X
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STA.l $7F6100, X
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STA.l $7F6200, X
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STA.l $7F6300, X
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STA.l $7F6400, X
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STA.l $7F6500, X
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STA.l $7F6600, X
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STA.l $7F6700, X
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STA.l $7F6800, X
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STA.l $7F6900, X
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STA.l $7F6A00, X
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STA.l $7F6B00, X
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STA.l $7F6C00, X
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STA.l $7F6D00, X
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STA.l $7F6E00, X
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STA.l $7F6F00, X
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RTL
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;--------------------------------------------------------------------------------
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CopyExtendedSaveFileToWRAM:
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PHA
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PHB
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LDA.w #$0FFF
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LDX.w #ExtendedSaveDataSRAM
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LDY.w #ExtendedSaveDataWRAM
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MVN $7F, !SRAMBank
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PLB
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PLA
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STA.l $7EC00D ; What we wrote over. Keep this write last.
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RTL
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;--------------------------------------------------------------------------------
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CopyExtendedWRAMSaveFileToSRAM:
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PHB
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LDA.w #$0FFF
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LDX.w #ExtendedSaveDataSRAM
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LDY.w #ExtendedSaveDataWRAM
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MVN !SRAMBank, $7F
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PLB
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TDC
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TAX
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RTL
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