mysql官方文档
http://dev.mysql.com/doc/internals/en/integer.html
mysql-protocol中对编码长度整数型的规则
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mysql-protocol中对编码长度整数型的规则
read_lc_int(buf):
"""
Takes a buffer and reads an length code string from the start.
Returns a tuple with buffer less the integer and the integer read.
"""
if not buf:
raise ValueError("Empty buffer.")
lcbyte = buf[0]
if lcbyte == 251:
return (buf[1:], None)
elif lcbyte < 251:
return (buf[1:], int(lcbyte))
elif lcbyte == 252:
return (buf[3:], struct_unpack(‘<xH‘, buf[0:3])[0])
elif lcbyte == 253:
return (buf[4:], struct_unpack(‘<I‘, buf[1:4] + b‘\x00‘)[0])
elif lcbyte == 254:
return (buf[9:], struct_unpack(‘<xQ‘, buf[0:9])[0])
else:
raise ValueError("Failed reading length encoded integer")