STM32L4R5板子CRC程序的问题

chenbingjy

代码：

1. #include "main.h"
   
2. 
   
3. /** @addtogroup STM32L4xx_HAL_Examples
   
4.   * @{
   
5.   */
   
6. 
   
7. /** @addtogroup CRC_UserDefinedPolynomial
   
8.   * @{
   
9.   */
   
10. 
    
11. /* Private typedef -----------------------------------------------------------*/
    
12. /* Private define ------------------------------------------------------------*/
    
13. /* aDataBuffer is 32 bit long*/
    
14. #define BUFFER_SIZE 1
    
15. 
    
16. /* The user defined polynomial*/
    
17. #define CRC_POLYNOMIAL_8B 0x9B /* X^8 + X^7 + X^4 + X^3 + X + 1 */
    
18. 
    
19. /* Private macro -------------------------------------------------------------*/
    
20. /* Private variables ---------------------------------------------------------*/
    
21. /* CRC handler declaration */
    
22. CRC_HandleTypeDef   CrcHandle;
    
23. 
    
24. /* Used for storing CRC Value */
    
25. __IO uint32_t uwCRCValue = 0;
    
26. 
    
27. /* Buffer containing the data on which the CRC will be calculated
    
28.   (one-word buffer in this example) */
    
29. static const uint32_t aDataBuffer = 0x1234;
    
30. 
    
31. /* Expected CRC Value */
    
32. uint32_t uwExpectedCRCValue = 0xEF;
    
33. 
    
34. /* Private function prototypes -----------------------------------------------*/
    
35. void SystemClock_Config(void);
    
36. static void Error_Handler(void);
    
37. 
    
38. /* Private functions ---------------------------------------------------------*/
    
39. 
    
40. /**
    
41.   * @brief  Main program
    
42.   * [url=home.php?mod=space&uid=271674]@param[/url]  None
    
43.   * @retval None
    
44.   */
    
45. int main(void)
    
46. {
    
47.   
    
48.   /* STM32L4xx HAL library initialization:
    
49.        - Configure the Flash prefetch
    
50.        - Systick timer is configured by default as source of time base, but user
    
51.          can eventually implement his proper time base source (a general purpose
    
52.          timer for example or other time source), keeping in mind that Time base
    
53.          duration should be kept 1ms since PPP_TIMEOUT_VALUEs are defined and
    
54.          handled in milliseconds basis.
    
55.        - Set NVIC Group Priority to 4
    
56.        - Low Level Initialization
    
57.      */
    
58.   HAL_Init();
    
59.   
    
60.   /* Configure the system clock to 120 MHz */
    
61.   SystemClock_Config();
    
62. 
    
63.   /* Configure LED1 and LED3 */
    
64.   BSP_LED_Init(LED1);
    
65.   BSP_LED_Init(LED3);
    
66. 
    
67.   /*##-1- Configure the CRC peripheral #######################################*/
    
68.   CrcHandle.Instance = CRC;
    
69. 
    
70.   /* The default polynomial is not used. It is required to defined it in CrcHandle.Init.GeneratingPolynomial*/  
    
71.   CrcHandle.Init.DefaultPolynomialUse    = DEFAULT_POLYNOMIAL_DISABLE;
    
72.   
    
73.   /* Set the value of the polynomial */
    
74.   CrcHandle.Init.GeneratingPolynomial    = CRC_POLYNOMIAL_8B;
    
75.   
    
76.   /* The user-defined generating polynomial generates a
    
77.      8-bit long CRC */
    
78.   CrcHandle.Init.CRCLength               = CRC_POLYLENGTH_8B;
    
79. 
    
80.   /* The default init value is used */
    
81.   CrcHandle.Init.DefaultInitValueUse     = DEFAULT_INIT_VALUE_ENABLE;
    
82. 
    
83.   /* The input data are not inverted */
    
84.   CrcHandle.Init.InputDataInversionMode  = CRC_INPUTDATA_INVERSION_NONE;
    
85. 
    
86.   /* The output data are not inverted */
    
87.   CrcHandle.Init.OutputDataInversionMode = CRC_OUTPUTDATA_INVERSION_DISABLE;
    
88. 
    
89.   /* The input data are 32-bit long */
    
90.   CrcHandle.InputDataFormat              = CRC_INPUTDATA_FORMAT_WORDS;
    
91. 
    
92.   if (HAL_CRC_Init(&CrcHandle) != HAL_OK)
    
93.   {
    
94.     /* Initialization Error */
    
95.     Error_Handler();
    
96.   }
    
97. 
    
98.   /*##-2- Compute the CRC of "aDataBuffer" ###################################*/
    
99.   uwCRCValue = HAL_CRC_Calculate(&CrcHandle, (uint32_t *)&aDataBuffer, BUFFER_SIZE);
    
100. 
     
101.   /*##-3- Compare the CRC value to the Expected one ##########################*/
     
102.   if (uwCRCValue != uwExpectedCRCValue)
     
103.   {
     
104.     /* Wrong CRC value: Turn LED3 on */
     
105.     Error_Handler();
     
106.   }
     
107.   else
     
108.   {
     
109.     /* Right CRC value: Turn LED1 on */
     
110.     BSP_LED_On(LED1);
     
111.   }
     
112. 
     
113.   /* Infinite loop */
     
114.   while (1)
     
115.   {
     
116.   }
     
117. }

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我想知道怎么算出来的。于是我写了一个C程序验证

1. #include "stdio.h"
   
2. 
   
3. #define uint32_t unsigned  int
   
4. #define uint16_t unsigned short
   
5. #define uint8_t  unsigned char
   
6. 
   
7. #define BUFFER_SIZE    1
   
8. 
   
9. uint32_t  temp;
   
10. 
    
11. static const uint32_t aDataBuffer = 0x1234;
    
12. 
    
13. /******************************************************************************
    
14. * Name:    CRC-32/MPEG-2  x32+x26+x23+x22+x16+x12+x11+x10+x8+x7+x5+x4+x2+x+1
    
15. * Poly:    0x4C11DB7
    
16. * Init:    0xFFFFFFF
    
17. * Refin:   False
    
18. * Refout:  False
    
19. * Xorout:  0x0000000
    
20. *****************************************************************************/
    
21. uint32_t crc32_mpeg_2(uint32_t *data, uint16_t length)
    
22. {
    
23.     uint8_t i;
    
24.     uint32_t crc = 0xffffffff;  // Initial value
    
25.     while(length--)
    
26.     {
    
27.         crc ^= (*data++) << 0;
    
28.         for (i = 0; i < 32; ++i)
    
29.         {
    
30.             if ( crc & 0x80000000 )
    
31.                 crc = (crc << 1) ^ 0x0000009b;
    
32.             else
    
33.                 crc <<= 1;
    
34.         }
    
35.     }
    
36.     return crc;
    
37. }
    
38. 
    
39. 
    
40. void main(void)
    
41. {
    
42.         temp=crc32_mpeg_2(&aDataBuffer, BUFFER_SIZE);
    
43.         printf("crc32 value=:%x\r\n",temp);
    
44. }

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结果得到结果：

得到的值是0xfff75e7f

不是0xef.

请高手指教，谢谢！