nghttp2/mkhufftbl.py

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#!/usr/bin/env python
import re
import sys
class Node:
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def __init__(self, term = None):
self.term = term
self.left = None
self.right = None
self.trans = []
self.id = None
self.accept = False
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def to_bin(s):
res = []
for i in range(0, len(s), 8):
x = s[i:i+8]
x += '0'*(8 - len(x))
a = 0
for j in range(8):
a *= 2
a += ord(x[j]) - ord('0')
res.append(a) #chr(a))
return res
nodes = []
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def insert(node, sym, bits):
if len(bits) == 0:
node.term = sym
return
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else:
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if bits[0] == '0':
if node.left is None:
node.left = Node()
child = node.left
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else:
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if node.right is None:
node.right = Node()
child = node.right
insert(child, sym, bits[1:])
def traverse(node, bits, syms, start_node, root, depth):
if depth == 4:
if 256 in syms:
syms = []
node = None
start_node.trans.append((node, bits, syms))
return
if node.term is not None:
node = root
def go(node, bit):
nbits = list(bits)
nbits.append(bit)
nsyms = list(syms)
if node.term is not None:
nsyms.append(node.term)
traverse(node, nbits, nsyms, start_node, root, depth + 1)
go(node.left, 0)
go(node.right, 1)
idseed = 0
def dfs_setid(node, prefix):
if node.term is not None:
return
if len(prefix) <= 7 and [1] * len(prefix) == prefix:
node.accept = True
global idseed
node.id = idseed
idseed += 1
dfs_setid(node.left, prefix + [0])
dfs_setid(node.right, prefix + [1])
def dfs(node, root):
if node is None:
return
traverse(node, [], [], node, root, 0)
dfs(node.left, root)
dfs(node.right, root)
NGHTTP2_HUFF_ACCEPTED = 1
NGHTTP2_HUFF_SYM = 1 << 1
def dfs_print(node):
if node.term is not None:
return
print '/* {} */'.format(node.id)
print '{'
for nd, bits, syms in node.trans:
outlen = len(syms)
flags = 0
if outlen == 0:
out = 0
else:
assert(outlen == 1)
out = syms[0]
flags |= NGHTTP2_HUFF_SYM
if nd is None:
id = -1
else:
id = nd.id
if id is None:
# if nd.id is None, it is a leaf node
id = 0
flags |= NGHTTP2_HUFF_ACCEPTED
elif nd.accept:
flags |= NGHTTP2_HUFF_ACCEPTED
print ' {{{}, 0x{:02x}, {}}},'.format(id, flags, out)
print '},'
dfs_print(node.left)
dfs_print(node.right)
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symbol_tbl = [(None, 0) for i in range(257)]
tables = {}
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root = Node()
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for line in sys.stdin:
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m = re.match(r'.*\(\s*(\d+)\)\s+([|01]+)\s+(\S+)\s+\[\s*(\d+)\].*', line)
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if m:
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#print m.group(1), m.group(2), m.group(4)
if len(m.group(3)) > 8:
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raise Error('Code is more than 4 bytes long')
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sym = int(m.group(1))
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bits = re.sub(r'\|', '', m.group(2))
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nbits = int(m.group(4))
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assert(len(bits) == nbits)
binpat = to_bin(bits)
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assert(len(binpat) == (nbits+7)/8)
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symbol_tbl[sym] = (binpat, nbits, m.group(3))
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#print "Inserting", sym
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insert(root, sym, bits)
dfs_setid(root, [])
dfs(root, root)
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print '''\
typedef struct {
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uint32_t nbits;
uint32_t code;
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} nghttp2_huff_sym;
'''
print '''\
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const nghttp2_huff_sym huff_sym_table[] = {'''
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for i in range(257):
pat = list(symbol_tbl[i][0])
pat += [0]*(4 - len(pat))
print '''\
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{{ {}, 0x{}u }}{}\
'''.format(symbol_tbl[i][1], symbol_tbl[i][2], ',' if i < 256 else '')
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print '};'
print ''
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print '''\
enum {{
NGHTTP2_HUFF_ACCEPTED = {},
NGHTTP2_HUFF_SYM = {}
}} nghttp2_huff_decode_flag;
'''.format(NGHTTP2_HUFF_ACCEPTED, NGHTTP2_HUFF_SYM)
print '''\
typedef struct {
int16_t state;
uint8_t flags;
uint8_t sym;
} nghttp2_huff_decode;
'''
print '''\
const nghttp2_huff_decode huff_decode_table[][16] = {'''
dfs_print(root)
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print '};'