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Compute and write save checksum on new file creation

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cassidoxa
2023-02-21 14:58:24 -05:00
parent aed9166f48
commit 02786974ad
3 changed files with 19 additions and 4 deletions
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15
save.asm
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@@ -67,6 +67,21 @@ ValidateSRAM:
SEP #$30
RTL
;--------------------------------------------------------------------------------
WriteNewFileChecksum:
LDX.w #$0000 : TXA : - ; Checksum first $04FE bytes
CLC : ADC.l CartridgeSRAM, X
INX #2
CPX.w #$04FE : BNE -
LDX.w #$0000 : - ; Checksum extended save data
CLC : ADC.l ExtendedFileNameSRAM, X
INX #2
CPX.w #$0FFE : BNE -
STA.b Scrap00
LDA.w #$5A5A
SEC : SBC.b Scrap00
STA.l InverseChecksumSRAM
RTL
;--------------------------------------------------------------------------------
ClearExtendedSaveFile:
STA.l $700400, X ; what we wrote over
STA.l $700500, X