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149 lines
4.2 KiB
Python
149 lines
4.2 KiB
Python
# This script exists to auto-generate Http2HuffmanIncoming.h from the table
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# contained in the HPACK spec. It's pretty simple to run:
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# python make_incoming_tables.py < http2_huffman_table.txt > Http2HuffmanIncoming.h
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# where huff_incoming.txt is copy/pasted text from the latest version of the
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# HPACK spec, with all non-relevant lines removed (the most recent version
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# of huff_incoming.txt also lives in this directory as an example).
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import sys
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def char_cmp(x, y):
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rv = cmp(x['nbits'], y['nbits'])
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if not rv:
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rv = cmp(x['bpat'], y['bpat'])
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if not rv:
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rv = cmp(x['ascii'], y['ascii'])
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return rv
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characters = []
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for line in sys.stdin:
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line = line.rstrip()
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obracket = line.rfind('[')
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nbits = int(line[obracket + 1:-1])
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oparen = line.find(' (')
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ascii = int(line[oparen + 2:oparen + 5].strip())
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bar = line.find('|', oparen)
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space = line.find(' ', bar)
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bpat = line[bar + 1:space].strip().rstrip('|')
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characters.append({'ascii': ascii, 'nbits': nbits, 'bpat': bpat})
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characters.sort(cmp=char_cmp)
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raw_entries = []
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for c in characters:
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raw_entries.append((c['ascii'], c['bpat']))
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class DefaultList(list):
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def __init__(self, default=None):
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self.__default = default
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def __ensure_size(self, sz):
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while sz > len(self):
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self.append(self.__default)
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def __getitem__(self, idx):
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self.__ensure_size(idx + 1)
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rv = super(DefaultList, self).__getitem__(idx)
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return rv
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def __setitem__(self, idx, val):
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self.__ensure_size(idx + 1)
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super(DefaultList, self).__setitem__(idx, val)
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def expand_to_8bit(bstr):
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while len(bstr) < 8:
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bstr += '0'
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return int(bstr, 2)
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table = DefaultList()
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for r in raw_entries:
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ascii, bpat = r
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ascii = int(ascii)
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bstrs = bpat.split('|')
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curr_table = table
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while len(bstrs) > 1:
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idx = expand_to_8bit(bstrs[0])
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if curr_table[idx] is None:
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curr_table[idx] = DefaultList()
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curr_table = curr_table[idx]
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bstrs.pop(0)
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idx = expand_to_8bit(bstrs[0])
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curr_table[idx] = {'prefix_len': len(bstrs[0]),
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'mask': int(bstrs[0], 2),
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'value': ascii}
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def output_table(table, name_suffix=''):
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max_prefix_len = 0
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for i, t in enumerate(table):
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if isinstance(t, dict):
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if t['prefix_len'] > max_prefix_len:
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max_prefix_len = t['prefix_len']
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elif t is not None:
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output_table(t, '%s_%s' % (name_suffix, i))
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tablename = 'HuffmanIncoming%s' % (name_suffix if name_suffix else 'Root',)
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entriestable = tablename.replace('HuffmanIncoming', 'HuffmanIncomingEntries')
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sys.stdout.write('static HuffmanIncomingEntry %s[] = {\n' % (entriestable,))
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prefix_len = 0
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value = 0
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ptr = 'nullptr'
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for i in range(256):
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t = table[i]
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if isinstance(t, dict):
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prefix_len = t['prefix_len']
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value = t['value']
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ptr = 'nullptr'
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elif t is not None:
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prefix_len = 0
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value = 0
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subtable = '%s_%s' % (name_suffix, i)
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ptr = '&HuffmanIncoming%s' % (subtable,)
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sys.stdout.write(' { %s, %s, %s }' %
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(ptr, value, prefix_len))
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if i < 255:
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sys.stdout.write(',')
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sys.stdout.write('\n')
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sys.stdout.write('};\n')
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sys.stdout.write('\n')
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sys.stdout.write('static HuffmanIncomingTable %s = {\n' % (tablename,))
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sys.stdout.write(' %s,\n' % (entriestable,))
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sys.stdout.write(' %s\n' % (max_prefix_len,))
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sys.stdout.write('};\n')
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sys.stdout.write('\n')
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sys.stdout.write('''/*
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* THIS FILE IS AUTO-GENERATED. DO NOT EDIT!
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*/
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#ifndef mozilla__net__Http2HuffmanIncoming_h
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#define mozilla__net__Http2HuffmanIncoming_h
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namespace mozilla {
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namespace net {
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struct HuffmanIncomingTable;
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struct HuffmanIncomingEntry {
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HuffmanIncomingTable *mPtr;
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uint16_t mValue;
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uint8_t mPrefixLen;
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};
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struct HuffmanIncomingTable {
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HuffmanIncomingEntry *mEntries;
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uint8_t mPrefixLen;
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};
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''')
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output_table(table)
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sys.stdout.write('''} // namespace net
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} // namespace mozilla
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#endif // mozilla__net__Http2HuffmanIncoming_h
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''')
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