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https://github.com/notwa/mm
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86 lines
1.8 KiB
Cython
86 lines
1.8 KiB
Cython
# Based on uCON64's N64 checksum algorithm by Andreas Sterbenz
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from libc.stdint cimport uint32_t, uint8_t
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# ulong must be 32 bits since we expect them to overflow as such
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ctypedef uint32_t ulong
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ctypedef uint8_t uchar
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from zlib import crc32
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crc_seeds = {
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6101: 0xF8CA4DDC,
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6102: 0xF8CA4DDC,
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6103: 0xA3886759,
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6105: 0xDF26F436,
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6106: 0x1FEA617A,
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}
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bootcode_crcs = {
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0x6170A4A1: 6101,
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0x90BB6CB5: 6102,
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0x0B050EE0: 6103,
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0x98BC2C86: 6105,
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0xACC8580A: 6106,
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}
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cdef ulong ROL(ulong i, ulong b):
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return (i << b) | (i >> (32 - b))
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cdef ulong R4(uchar *b):
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return b[0]*0x1000000 + b[1]*0x10000 + b[2]*0x100 + b[3]
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cdef object _crc(uchar *data, ulong bootcode, uchar *lookup):
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cdef:
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ulong seed = crc_seeds[bootcode]
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ulong t1, t2, t3, t4, t5, t6
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ulong i, d, b, r, o
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ulong crc1, crc2
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t1 = t2 = t3 = t4 = t5 = t6 = seed
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for i in range(0x1000, 0x101000, 4):
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d = R4(data + i)
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if t6 + d < t6:
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t4 += 1
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t6 += d
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t3 ^= d
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r = ROL(d, d & 0x1F)
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t5 += r
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if t2 > d:
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t2 ^= r
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else:
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t2 ^= t6 ^ d
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if bootcode == 6105:
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o = i & 0xFF
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t1 += R4(lookup + o)^ d
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else:
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t1 += t5
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if bootcode == 6103:
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crc1 = (t6 ^ t4) + t3
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crc2 = (t5 ^ t2) + t1
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elif bootcode == 6106:
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crc1 = t6*t4 + t3
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crc2 = t5*t2 + t1
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else:
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crc1 = t6 ^ t4 ^ t3
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crc2 = t5 ^ t2 ^ t1
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return crc1, crc2
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def crc(f, bootcode=6105):
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f.seek(0)
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data = f.read()
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lookup = data[0x750:0x850]
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return _crc(data, bootcode, lookup)
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def bootcode_version(f):
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f.seek(0x40)
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return bootcode_crcs[crc32(f.read(0x1000 - 0x40)) & 0xFFFFFFFF]
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