92 lines
2.4 KiB
Python
Executable File
92 lines
2.4 KiB
Python
Executable File
#!/usr/bin/env python
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# adc/xor routine from:
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# https://stackoverflow.com/questions/17411712/finding-seeds-for-a-5-byte-prng
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# Pretty good choices for 8 bit seeds
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adcxor_8bit = [
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(0x03, 0x045),
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(0x03, 0x073),
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(0x03, 0x085),
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(0x03, 0x0b3),
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(0x0d, 0x04d),
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(0x0d, 0x08d),
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(0x23, 0x033),
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(0x23, 0x0f3),
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(0x3b, 0x03f),
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(0x3b, 0x0ff),
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(0x45, 0x07f),
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(0x45, 0x0bf),
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(0x5d, 0x073),
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(0x5d, 0x0b3),
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(0x73, 0x00d),
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(0x73, 0x0cd),
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(0x7d, 0x005),
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(0x7d, 0x033),
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(0x7d, 0x0c5),
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(0x7d, 0x0f3),
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]
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def get_prng8(bits, adc, xor):
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order = []
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r = 0
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for i in range(2**bits):
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r=(((r>>(bits-1)) & 1)+r+r+adc)^xor
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r&=(1<<(bits-1)) | ((1<<(bits-1))-1)
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order.append(r)
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return order
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if __name__ == '__main__':
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gen_16_bit = False
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summary = True
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show = True
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if gen_16_bit:
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random_bits = 16
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else:
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random_bits = 8
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valid_seeds = []
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mc = 0
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for BITS in range(2, random_bits + 1):
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adc = 1 # Only odd add values produce useful results
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while True:
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xor = 1 # Only odd add values produce useful results
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while True:
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r = 0
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c = ~0
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values = []
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while True:
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r=(((r>>(BITS-1)) & 1)+r+r+adc)^xor
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r&=(1<<(BITS-1)) | ((1<<(BITS-1))-1)
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c += 1
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values.append(r)
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if r == 0:
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break
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if c >= mc:
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mc = c
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valid_seeds.append((BITS, adc, xor))
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if not summary:
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print("BITS: %d adc: %04x, xor: %04x" % (BITS, adc, xor))
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xor += 2
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xor &= (1<<(BITS-1)) | ((1<<(BITS-1))-1)
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if xor == 1:
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break
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adc += 2
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adc &= ((1<<(BITS-1))-1) # * Do not check complements
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if adc == 1:
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break
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if summary:
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for bits, adc, xor in valid_seeds:
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print("BITS: %d adc(adc): %04x, xor(eor): %04x" % (bits, adc, xor))
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if show:
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values = get_prng8(bits, adc, xor)
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unique_check = set(values)
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if len(values) == len(unique_check):
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print("%d: %s" % (len(values), str(values)))
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else:
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print("Failed unique check")
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