crc32.c

00001 /*****************************************************************************
00002  *   crc32.c:  Ethernet CRC module file for NXP LPC230x Family Microprocessors
00003  *
00004  *   Copyright(C) 2006, NXP Semiconductor
00005  *   All rights reserved.
00006  *
00007  *   History
00008  *   2006.09.01  ver 1.00    Prelimnary version, first Release
00009  *
00010 ******************************************************************************/
00011 #include "lpc17xx_emac.h"                        /* LPC23xx/24xx definitions */
00012 #include "crc32.h"
00013 
00014 /******************************************************************************
00015 ** Function name:       CRC_init
00016 **
00017 ** Descriptions:        Begin CRC calculation.
00018 **
00019 ** parameters:          pointer to the CRC area.
00020 ** Returned value:      None
00021 **
00022 ******************************************************************************/
00023 void crc32_init(uint32_t *pCRC)
00024 {
00025     *pCRC = 0xffffffff;
00026 }
00027 
00028 /******************************************************************************
00029 ** Function name:       CRC32_add
00030 **
00031 ** Descriptions:        Calculate CRC value one at a time
00032 **
00033 ** parameters:          pointer to the CRC area, and passing value to get the CRC
00034 ** Returned value:      None
00035 **
00036 ******************************************************************************/
00037 void crc32_add(uint32_t *pCRC, uint8_t val8)
00038 {
00039     uint32_t i, poly;
00040     uint32_t entry;
00041     uint32_t crc_in;
00042     uint32_t crc_out;
00043 
00044     crc_in = *pCRC;
00045     poly = 0xEDB88320L;
00046     entry = (crc_in ^ ((uint32_t) val8)) & 0xFF;
00047     for (i = 0; i < 8; i++)
00048     {
00049         if (entry & 1)
00050             entry = (entry >> 1) ^ poly;
00051         else
00052             entry >>= 1;
00053     }
00054     crc_out = ((crc_in>>8) & 0x00FFFFFF) ^ entry;
00055     *pCRC = crc_out;
00056     return;
00057 }
00058 
00059 /******************************************************************************
00060 ** Function name:       CRC32_end
00061 **
00062 ** Descriptions:        Finish CRC calculation
00063 **
00064 ** parameters:          pointer to the CRC area.
00065 ** Returned value:      None
00066 **
00067 ******************************************************************************/
00068 void crc32_end(uint32_t *pCRC)
00069 {
00070     *pCRC ^= 0xffffffff;
00071 }
00072 
00073 /******************************************************************************
00074 ** Function name:       CRC32_bfr
00075 **
00076 ** Descriptions:        Get the CRC value based on size of the string.
00077 **
00078 ** parameters:          Pointer to the string, size of the string.
00079 ** Returned value:      CRC value
00080 **
00081 ******************************************************************************/
00082 uint32_t crc32_bfr(void *pBfr, uint32_t size)
00083 {
00084     uint32_t crc32;
00085     uint8_t  *pu8;
00086 
00087     crc32_init(&crc32);
00088     pu8 = (uint8_t *) pBfr;
00089     while (size-- != 0)
00090     {
00091         crc32_add(&crc32, *pu8);
00092         pu8++ ;
00093     }
00094     crc32_end(&crc32);
00095     return ( crc32 );
00096 }
00097 
00098 /*********************************************************************************
00099 **                            End Of File
00100 *********************************************************************************/