60 lines
990 B
Python
60 lines
990 B
Python
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#!/usr/bin/python
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# (64,30) linear block code stuff
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polynomial = 0260534236651
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# produce generator matrix g
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g = []
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for i in range(30):
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g.append(polynomial << i)
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for j in range(i):
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if g[i] & (1 << (33 + i - j)):
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g[i] ^= g[i-j-1]
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#print
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#for i in range(29,-1,-1):
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#print "0x%016x," % g[i]
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#print
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# produce check matrix h
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h = []
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for i in range(34):
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h.append(0)
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for j in range(30):
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h[i] |= (g[29-j] >> i) & 0x1
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h[i] <<= 1
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h[i] <<= 33
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h[i] |= (0x1 << i)
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#print
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#for i in range(34):
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#print "0x%016x," % h[i]
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#print
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# reverse the order
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g = g[::-1]
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h = h[::-1]
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def count_bits(n):
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i = 0
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while n != 0:
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n &= n - 1
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i += 1
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return i
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def gen_syndrome(c):
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assert c < 2**64
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s = 0
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# look for a faster GF(2) matrix multiplication algorithm
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for i in range(34):
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s <<= 1
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s |= (count_bits(c & h[i]) % 2)
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return s
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# optimized check table generation (sw_check_tables.h)
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for shift in range(8):
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for i in range(256):
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print "0x%09x, " % gen_syndrome(i<<(shift*8)),
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print
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