bs-x_sram_chk_rewrite

from struct import *
import sys

print("BS-X SRAM Checksum Fixer v0.3")
print("By LuigiBlood")

if (len(sys.argv) > 1):
    if (sys.argv[1] == "-f" and sys.argv[2] != ""):
        FILE = sys.argv[2]
        FIXflag = 1
    else:
        FILE = sys.argv[1]
        FIXflag = 0
    SRAMfile = open(FILE,"r+b")
    CHK1 = 0
    CHK2 = 0
    SRAMfile.seek(0)
    DATA = SRAMfile.read(0x3000)
    print("Checksum: " + hex(DATA[4] + (DATA[5] * 0x100)))
    print("Reverse Checksum: " + hex(DATA[2] + (DATA[3] * 0x100)))
    for i in range(0,0x3000):
        CHK2 += DATA[i]
    for i in range(2,6):
        CHK2 -= DATA[i]
    CHK2 += 0xFF
    CHK2 += 0xFF

    CHK2 &= 0xFFFF
    CHK1 = CHK2 ^ 0xFFFF
    print("Calculated Checksum: " + hex(CHK2))
    print("Calculated Reverse Checksum: " + hex(CHK1))
    if (FIXflag == 1):
        SRAMfile.seek(2)
        SRAMfile.write(pack("2H", CHK1, CHK2))
        print("Checksum Fixed!")
else:
    print("Usage: " + sys.argv[0] + " [-f] <SRAM File Path>")
    print("   -f : Fix Checksum (Optional)")