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| author | Martin Panter <vadmium+py@gmail.com> | 2015-12-11 05:41:48 (GMT) |
|---|---|---|
| committer | Martin Panter <vadmium+py@gmail.com> | 2015-12-11 05:41:48 (GMT) |
| commit | 70fe09bc67098756349c1dc35e0d8d85a4c465cf (patch) | |
| tree | 5f7d39b1137ceb3ed2bb3584ec283d2f73fe673d /Doc/library/binascii.rst | |
| parent | 8c0b5b998ae3319294a366cfb0bdad9fc88ff1fc (diff) | |
| parent | b82032f935962d13220bba52d26ac607149485eb (diff) | |
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Issue #22341: Merge CRC doc from 3.5
Diffstat (limited to 'Doc/library/binascii.rst')
| -rw-r--r-- | Doc/library/binascii.rst | 23 |
1 files changed, 11 insertions, 12 deletions
diff --git a/Doc/library/binascii.rst b/Doc/library/binascii.rst index 441aa57..0cd18b1 100644 --- a/Doc/library/binascii.rst +++ b/Doc/library/binascii.rst @@ -115,15 +115,16 @@ The :mod:`binascii` module defines the following functions: possibly the last fragment). -.. function:: crc_hqx(data, crc) +.. function:: crc_hqx(data, value) - Compute the binhex4 crc value of *data*, starting with an initial *crc* and - returning the result. + Compute the binhex4 crc value of *data*, starting with *value* as the + initial crc, and return the result. -.. function:: crc32(data[, crc]) +.. function:: crc32(data[, value]) - Compute CRC-32, the 32-bit checksum of data, starting with an initial crc. This + Compute CRC-32, the 32-bit checksum of *data*, starting with an + initial CRC of *value*. The default initial CRC is zero. The algorithm is consistent with the ZIP file checksum. Since the algorithm is designed for use as a checksum algorithm, it is not suitable for use as a general hash algorithm. Use as follows:: @@ -131,15 +132,13 @@ The :mod:`binascii` module defines the following functions: print(binascii.crc32(b"hello world")) # Or, in two pieces: crc = binascii.crc32(b"hello") - crc = binascii.crc32(b" world", crc) & 0xffffffff + crc = binascii.crc32(b" world", crc) print('crc32 = {:#010x}'.format(crc)) -.. note:: - To generate the same numeric value across all Python versions and - platforms use crc32(data) & 0xffffffff. If you are only using - the checksum in packed binary format this is not necessary as the - return value is the correct 32bit binary representation - regardless of sign. + .. versionchanged:: 3.0 + The result is always unsigned. + To generate the same numeric value across all Python versions and + platforms, use ``crc32(data) & 0xffffffff``. .. function:: b2a_hex(data) |