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checksum.c
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/* modified base on linux source */
#include "checksum.h"
/** CRC table for the CRC-16. The poly is 0x11021 (x^16 + x^15 + x^2 + 1) */
uint16_t const crc16_table[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
};
/**
* crc16 - compute the CRC-16 for the data buffer
* @crc: previous CRC value
* @buffer: data pointer
* @len: number of bytes in the buffer
*
* Returns the updated CRC value.
*/
uint16_t crc16(uint16_t crc, uint8_t const *buffer, size_t len)
{
while (len--)
crc = crc16_byte(crc, *buffer++);
return crc;
}
uint16_t ipcheck(uint16_t* buffer, int size)
{
unsigned long cksum = 0;
while(size>1)
{
cksum += *buffer++;
size -= sizeof(uint16_t);
}
if(size)
{
cksum += *(uint8_t *)buffer;
}
cksum = (cksum>>16) + (cksum&0xffff);
cksum += (cksum>>16);
cksum = (uint16_t)~cksum;
/* big endian */
cksum = (cksum>>8) | (cksum<<8);
return (uint16_t)(cksum);
}
uint16_t checksum(uint8_t type,uint8_t const *buffer, size_t len)
{
if(type == TYPE_CRC){
return crc16(0,buffer,len);
}else if(type == TYPE_IPSUM){
return ipcheck((uint16_t*)buffer,len);
}
return -1;
}
/*
int main(void)
{
uint16_t res = 0x3b5a;
uint8_t a[4]={0x00,0x80,0x00,0x00};
uint8_t b[38]={
0x00, 0x81 ,0x00 ,0x22 ,0x53 ,0x70 ,0x72 ,0x65 ,0x61 ,0x64 ,0x74 ,0x72 ,0x75 ,0x6d ,0x20
,0x42 ,0x6f ,0x6f ,0x74 ,0x20 ,0x42 ,0x6c ,0x6f
,0x63 ,0x6b ,0x20 ,0x76 ,0x65 ,0x72 ,0x73 ,0x69
,0x6f ,0x6e ,0x20 ,0x39 ,0x2e ,0x39 ,0x00
};
printf("0x%x \n",checksum(TYPE_CRC,a,4));
printf("0x%x \n",checksum(TYPE_IPSUM,a,4));
printf("0x%x \n",checksum(TYPE_IPSUM,b,38));
return 0;
}
*/