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标题：让STM32的CRC32与主流计算工具一致，Make STM32F CRC compatible with windows/winzip/winrar

1楼

McuIsp 发表于：2009-05-13 20:45:22

  //CopyRight:www.mcuisp.com
//版权: 单片机在线编程网
/**********************
reverse bits of DWORD
Input:
   u32 data -- the input
Output:
   u32 data -- the output
**********************/
u32 revbit(u32 data)
{
   asm("rbit r0,r0");
   return data;
};
/**********************
Calculate CRC32 of DWORD data array.
Input:
   u32 *dworddata -- the array point
   u32 dwordcount -- the data len in DWORD
Output:
   u32 CRC32 -- the result
**********************/
u32 CalcCRC32(u32 *dworddata,u32 dwordcount)
{
   u32 ui32;
   RCC_AHBPeriphClockCmd(RCC_AHBPeriph_CRC,ENABLE);
   CRC->CR=1;
   asm("NOP");asm("NOP");asm("NOP");//貌似CRC复位后需等会送数
   for(;dwordcount>0;dwordcount--)
   {
     ui32=*dworddata;
     dworddata++;
     ui32=revbit(ui32);//输入位序颠倒一下
     CRC->DR=ui32;
   }
   ui32=CRC->DR;
   ui32=revbit(ui32);//输出位序颠倒一下
   ui32^=0xffffffff;//异或
   return ui32;
};
/**********************
test the CalcCRC32.
Input:
   None
Output:
   None
**********************/
void testCRC(void)
{
   u32 ui32;
   union{
     u32 databuf32[256/4];
     u8 databuf8[256];
   };
   databuf32[0]=0x41424344;//实际为44 43 42 41
   ui32=CalcCRC32(databuf32+0,1);
   Lcd_ClrRect(0,0,128,64);
   DisplayBytes("CRC,Input:",0,0,65535,16,16);
   DisplayAscii(toHex(databuf8[0]>>4),0,16);
   DisplayAscii(toHex(databuf8[0]>>0),8,16);
   DisplayAscii(toHex(databuf8[1]>>4),16,16);
   DisplayAscii(toHex(databuf8[1]>>0),24,16);
   DisplayAscii(toHex(databuf8[2]>>4),32,16);
   DisplayAscii(toHex(databuf8[2]>>0),40,16);
   DisplayAscii(toHex(databuf8[3]>>4),48,16);
   DisplayAscii(toHex(databuf8[3]>>0),56,16);//44434241
   DisplayBytes("CRC,Output:",0,32,65535,16,16);
   DisplayAscii(toHex(ui32>>28),0,48);
   DisplayAscii(toHex(ui32>>24),8,48);
   DisplayAscii(toHex(ui32>>20),16,48);
   DisplayAscii(toHex(ui32>>16),24,48);
   DisplayAscii(toHex(ui32>>12),32,48);
   DisplayAscii(toHex(ui32>>8),40,48);
   DisplayAscii(toHex(ui32>>4),48,48);
   DisplayAscii(toHex(ui32>>0),56,48);//847a7f6e
}
//可以看出，stm32f与主流计算工具有三点差别：
//1、输入位序颠倒,只需数据输入前颠倒位序
//2、输出位序颠倒，获得结果后再颠倒回来。
//3、异或0xffffffff

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