91 lines
3.2 KiB
GDScript
91 lines
3.2 KiB
GDScript
extends Node
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const STRUCT := preload('res://scripts/struct.gd')
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const SLOT_IN_USE := 0xE41B
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var struct_types := STRUCT.get_base_structarraytypes()
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# FFV SRAM is 4 slots of 0x700byte save files
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# $0000-$06FF - Save Slot 1
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# $0700-$0DFF - Save Slot 2
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# $0E00-$14FF - Save Slot 3
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# $1500-$1BFF - Save Slot 4
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# $1C00-$1FEF - Empty
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# $1FF0-$1FF7 - Checksum (2 bytes per slot)
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# $1FF8-$1FFF - use table - contains $E41B if a slot is in use (deleting a save will just change this)
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# Checksum just sums up every 16bit word from 0x000-0x600 of the save slot, using the carry flag.
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# The carry flag means that it is not strictly modulo arithmetic, but you have to add 1 every time you pass 0xFFFF
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# Offsets within save slot
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# $000:600 = $500:B00 in WRAM (0x7E0500:0x7E0B00) only values that don't match are things like game frame timer which increments immediately after load
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#
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# $000-$04F - Character Slot 1
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# $050=$09F - Character Slot 2
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# $0A0=$0EF - Character Slot 3
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# $0F0=$13F - Character Slot 4
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# $447-$449 - Current Gil
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#
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# $5D8 - Current Map X position
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# $5D9 - Current Map Y position
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#
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# $600-$6FF - Appears to be unused and zeroed out, not used for checksum. Maybe we can use it for cool metadata? :)
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func get_slot_checksum(slot: StreamPeerBuffer) -> int:
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slot.seek(0)
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var checksum := 0
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for i in 0x600: # Last 0x100 bytes aren't checksummed
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checksum += slot.get_u16()
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if checksum > 0xFFFF: # Addition of shorts can only overflow
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checksum &= 0xFFFF
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if i < 0x5FF:
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checksum += 1 # TODO: confirm this carry flag edge case is correct!
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return checksum
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func get_struct(buffer: StreamPeer, struct_name: String) -> Dictionary:
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# Does not seek to the start of the buffer.
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# Make sure it is set to where you want to start reading.
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if not (struct_name in struct_types):
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print_debug('Attempted to get undeclared struct: "%s"' % struct_name)
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return {}
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return struct_types[struct_name].get_value(buffer, [0, 0])
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func get_save_slot(sram: File, slot_id: int):
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var buffer := StreamPeerBuffer.new()
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sram.seek(0x700 * slot_id)
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buffer.set_data_array(sram.get_buffer(0x700))
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return buffer
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func save_slot(sram: File, slot_id: int, slot: StreamPeerBuffer):
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sram.seek(0x700 * slot_id)
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sram.store_buffer(slot.data_array)
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sram.seek(0x1FF0 + (slot_id*2))
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sram.store_16(get_slot_checksum(slot))
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sram.seek(0x1FF8 + (slot_id*2))
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sram.store_16(SLOT_IN_USE)
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func delete_save_slot(sram: File, slot_id: int):
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sram.seek(0x1FF8 + (slot_id*2))
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sram.store_16(0)
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func _ready():
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var file := File.new()
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var error = file.open('res://data/SNES_save.tsv', File.READ)
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if error == OK:
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var current_struct: STRUCT.Struct
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var line_num := 0 # Currently only used for step-through debugging
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while file.get_position() < file.get_len():
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var line := file.get_csv_line('\t')
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line_num += 1
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var size = line.size()
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if size < 2:
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continue
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# Size is at least 2
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var type := line[0]
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var label := line[1]
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if type == 'struct':
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# New struct declaration
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current_struct = STRUCT.Struct.new()
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struct_types[label] = current_struct
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elif type and label:
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# TODO: Maybe store the trailing comments somewhere?
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current_struct.members.append([label, STRUCT.get_structarraytype(type, struct_types)])
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file.close()
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