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annotate paraspace/tools.py @ 126:ff6f869273b7

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Fix wrong init value for computing checksum
author Thinker K.F. Li <thinker@codemud.net>
date Mon, 08 Aug 2011 17:26:05 +0800
parents b7432d6f7e93
children
rev   line source
68
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
diff changeset
1 base = 65521
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
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2
126
ff6f869273b7 Fix wrong init value for computing checksum
Thinker K.F. Li <thinker@codemud.net>
parents: 68
diff changeset
3 adler32_init_value = 1
ff6f869273b7 Fix wrong init value for computing checksum
Thinker K.F. Li <thinker@codemud.net>
parents: 68
diff changeset
4
68
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
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5 def adler32(adler, buf, offset, sz):
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
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6 sum1 = adler & 0xffff
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
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7 sum2 = (adler >> 16) & 0xffff
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
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8 for off in range(offset, offset + sz):
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
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9 sum1 = (sum1 + ord(buf[off])) % base
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
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10 sum2 = (sum2 + sum1) % base
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
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11 pass
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
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12 r = (sum2 << 16) | sum1
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
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13 return r
b7432d6f7e93 adler32
Thinker K.F. Li <thinker@codemud.net>
parents:
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14