/*******************************************************************************************************
** Descriptions:		sd 卡驅(qū)動軟件包: SD卡相關工具函數(shù) ---- CRC校驗
********************************************************************************************************/
#include    "define.h"



#if SD_CRC_EN
//X16 + X12 + X5 + 1 余式表
uint16 const CRCTable[256]={0x0000,0x1021,0x2042,0x3063,0x4084,0x50a5,0x60c6,0x70e7,
							0x8108,0x9129,0xa14a,0xb16b,0xc18c,0xd1ad,0xe1ce,0xf1ef,
							0x1231,0x0210,0x3273,0x2252,0x52b5,0x4294,0x72f7,0x62d6,
							0x9339,0x8318,0xb37b,0xa35a,0xd3bd,0xc39c,0xf3ff,0xe3de,
							0x2462,0x3443,0x0420,0x1401,0x64e6,0x74c7,0x44a4,0x5485,
							0xa56a,0xb54b,0x8528,0x9509,0xe5ee,0xf5cf,0xc5ac,0xd58d,
							0x3653,0x2672,0x1611,0x0630,0x76d7,0x66f6,0x5695,0x46b4,
							0xb75b,0xa77a,0x9719,0x8738,0xf7df,0xe7fe,0xd79d,0xc7bc,
							0x48c4,0x58e5,0x6886,0x78a7,0x0840,0x1861,0x2802,0x3823,
							0xc9cc,0xd9ed,0xe98e,0xf9af,0x8948,0x9969,0xa90a,0xb92b,
							0x5af5,0x4ad4,0x7ab7,0x6a96,0x1a71,0x0a50,0x3a33,0x2a12,
							0xdbfd,0xcbdc,0xfbbf,0xeb9e,0x9b79,0x8b58,0xbb3b,0xab1a,
							0x6ca6,0x7c87,0x4ce4,0x5cc5,0x2c22,0x3c03,0x0c60,0x1c41,
							0xedae,0xfd8f,0xcdec,0xddcd,0xad2a,0xbd0b,0x8d68,0x9d49,
							0x7e97,0x6eb6,0x5ed5,0x4ef4,0x3e13,0x2e32,0x1e51,0x0e70,
							0xff9f,0xefbe,0xdfdd,0xcffc,0xbf1b,0xaf3a,0x9f59,0x8f78,
							0x9188,0x81a9,0xb1ca,0xa1eb,0xd10c,0xc12d,0xf14e,0xe16f,
							0x1080,0x00a1,0x30c2,0x20e3,0x5004,0x4025,0x7046,0x6067,
							0x83b9,0x9398,0xa3fb,0xb3da,0xc33d,0xd31c,0xe37f,0xf35e,
							0x02b1,0x1290,0x22f3,0x32d2,0x4235,0x5214,0x6277,0x7256,
							0xb5ea,0xa5cb,0x95a8,0x8589,0xf56e,0xe54f,0xd52c,0xc50d,
							0x34e2,0x24c3,0x14a0,0x0481,0x7466,0x6447,0x5424,0x4405,
							0xa7db,0xb7fa,0x8799,0x97b8,0xe75f,0xf77e,0xc71d,0xd73c,
							0x26d3,0x36f2,0x0691,0x16b0,0x6657,0x7676,0x4615,0x5634,
							0xd94c,0xc96d,0xf90e,0xe92f,0x99c8,0x89e9,0xb98a,0xa9ab,
							0x5844,0x4865,0x7806,0x6827,0x18c0,0x08e1,0x3882,0x28a3,
							0xcb7d,0xdb5c,0xeb3f,0xfb1e,0x8bf9,0x9bd8,0xabbb,0xbb9a,
							0x4a75,0x5a54,0x6a37,0x7a16,0x0af1,0x1ad0,0x2ab3,0x3a92,
							0xfd2e,0xed0f,0xdd6c,0xcd4d,0xbdaa,0xad8b,0x9de8,0x8dc9,
							0x7c26,0x6c07,0x5c64,0x4c45,0x3ca2,0x2c83,0x1ce0,0x0cc1,
							0xef1f,0xff3e,0xcf5d,0xdf7c,0xaf9b,0xbfba,0x8fd9,0x9ff8,
							0x6e17,0x7e36,0x4e55,0x5e74,0x2e93,0x3eb2,0x0ed1,0x1ef0
						   };

/********************************************************************************************************************
** 函數(shù)名稱: INT8U SD_GetCRC16()					Name:	  INT8U SD_GetCRC16()
** 功能描述: 計算CRC16								Function: calculate CRC16 
** 輸　  入: INT8U *pSource: 數(shù)據(jù)					Input:    INT8U *pSource: data
			 INT16U len    : 長度							  INT16U len    : len
** 輸 　 出: CRC16碼								Output:	  CRC16 code
********************************************************************************************************************/
uint16 SD_GetCRC16(uint8 *pSource, uint16 len)
{
	uint16 i;
	uint16 result = 0;

	for (i = 0; i < len; i++)
	    result = (result << 8) ^ (uint16)CRCTable[(result >> 8) ^ *pSource++];
	
	return result;
}

/*******************************************************************************************************************
** 函數(shù)名稱: INT8U SD_GetCmdByte6()					Name:	  INT8U SD_GetCmdByte6()
** 功能描述: 獲取SD卡命令的CRC7						Function: get the CRC7 of the command of SD card
** 輸　  入: INT8U cmd   : 命令						Input:    INT8U cmd   :	command
			 INT8U *param: 命令的參數(shù),長度為4字節(jié)			  INT8U *param: the param of command,length is 4 bytes
** 輸 　 出: CRC7碼									Output:	  CRC7 code
********************************************************************************************************************/
uint8 SD_GetCmdByte6(uint8 cmd, uint8 *param)
{
	uint8 i, j;
	uint8 reg = 0;
	uint8 array[5];
	
	array[0] = cmd;
	for (i = 1; i < 5; i++)						/* 將參數(shù)的順序重新排列 */
		array[i] = param[4 - i];
	
	for (i = 0; i < 5; i++)						/* 計算5個字節(jié)的CRC7 */
	{
	    for (j = 0; j < 8; j++)
	    {
			reg <<= 1;
			reg ^= ((((array[i] << j) ^ reg) & 0x80) ? 0x9 : 0);
	    }
	}
	
	return ((reg << 1) + 0x01) ;				/* 計算結(jié)果的CRC7左移一位,并將最低位置1 */
}
#endif