# -*- coding: utf-8 -*-

import Tkinter
import tkFileDialog

WIDTH = 16
TOPBIT = (1 << (WIDTH - 1))
crcTable = {}

class FindLocation(object):
    def __init__(self):
        #创建主窗口，用于容纳其它组件
        self.root = Tkinter.Tk()
        #给主窗口设置标题内容
        self.root.title("获取bin文件的crc校验码")
        #创建一个输入框，并设置尺寸
        self.default_value = Tkinter.StringVar()
        self.default_value.set('请输入bin文件全路径')
        self.ip_input = Tkinter.Entry(self.root,width=30,textvariable = self.default_value)
        
        #创建一个回显列表
        self.display_info = Tkinter.Listbox(self.root,width=50)
        
        #创建一个搜索文件的按钮
        self.getPath_button = Tkinter.Button(self.root,command = self.getPath,text = "获取文件")
        
        #创建一个查询结果的按钮
        self.result_button = Tkinter.Button(self.root,command = self.crcFast,text = "获取校验码")
        
        
    def gui_arrang(self):
        self.ip_input.pack()
        self.display_info.pack()
        self.getPath_button.pack()
        self.result_button.pack()
        
        
    def getPath(self):
        self.fname = tkFileDialog.askopenfilename()
        self.default_value.set(self.fname)
        
    def crcInit(self):
        SHIFT = WIDTH - 8
        for step in range(0,256):
            remainder = step << SHIFT
            for bit in range(8,0,-1):
                if remainder & TOPBIT:
                    remainder = ((remainder << 1) & 0xFFFF) ^0x1021
                else:
                    remainder = remainder <<1
            crcTable[step]=remainder
            #print("%x"%remainder)
            
    def crc16(self,cCRC,szData,rLen):
        for len in range(rLen):
            data = (cCRC >> 8) ^ ord(szData[len])
            cCRC = crcTable[data] ^ (cCRC << 8) & 0xFFFF
            
        return cCRC
        
    def crcFast(self):
        filePath = self.ip_input.get()
        
        tLen = 0
        rLen = 0
        szData = 0
        cCRC = 0
        self.crcInit()
        fp = open(filePath,'rb')
        fp.seek(0,2)
        iFileLen = fp.tell()
        fp.seek(0,0)
    
        while True:
            if (iFileLen - tLen) < 8192:
                rLen = iFileLen - tLen
            else:
                rLen = 8192
            
            szData = fp.read(rLen)
            cCRC = self.crc16(cCRC,szData,rLen)
            tLen += rLen
            if tLen >= iFileLen:
                break
            
        print "crc is %x\n" % cCRC
        fp.close()
        
        self.display_info.insert(0,"%x"%cCRC)
        self.display_info.insert(0,"this bin crc is :")    
        

def main():
    #初始化对象
    FL = FindLocation()
    #进行布局
    FL.gui_arrang()
    #主程序执行
    Tkinter.mainloop()


if __name__ == '__main__':
    
    main()