Compute and write save checksum on new file creation

events.asm

@@ -105,13 +105,11 @@ OnFileCreation:
 
         ; Set validity value and do some cleanup. Jump to checksum.
         LDA.w #$55AA : STA.l FileValiditySRAM
+        JSL.l WriteNewFileChecksum
         STZ.b Scrap00
         STZ.b Scrap01
-        LDX.b Scrap00
-        LDY.w #$0000
-        TYA
 
-JML.l InitializeSaveFile_build_checksum
+JML.l InitializeSaveFile_done
 ;--------------------------------------------------------------------------------
 OnFileLoad:
 	REP #$10 ; set 16 bit index registers

save.asm

@@ -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

vanillalabels.asm

@@ -14,6 +14,7 @@ Vram_EraseTilemaps_triforce = 008333
 Sound_LoadLightWorldSongBank = $008913
 Sound_LoadLightWorldSongBank_do_load = $00891D
 EnableForceBlank = $00893D
+SaveGameFile = $00894A ; long
 DungeonMask = $0098C0
 DecompSwordGfx = $00D308
 DecompShieldGfx = $00D348
@@ -75,6 +76,7 @@ OverworldMap_LoadSprGfx = $0ABAB9
 NameFile_MakeScreenVisible = $0CD7D1
 InitializeSaveFile = $0CDB3E
 InitializeSaveFile_build_checksum = $0CDBC0
+InitializeSaveFile_done = $0CDBDB
 GetRandomInt = $0DBA71
 OAM_AllocateFromRegionA = $0DBA80
 OAM_AllocateFromRegionB = $0DBA84