Comtrol eCos - Manual (Page 645)

Chapter 50. CRC Functions
CRC API
The package implements a number of CRC functions as described below. The API to these functions is in the
include file
cyg/crc/crc.h .
cyg_posix_crc32
This function implements a 32 bit CRC which is compliant to the POSIX 1008.2 Standard. This is the same as the
Linux cksum program.
cyg_uint32 cyg_posix_crc32(unsigned char ∗ s, int len);
The CRC calculation is run over the data pointed to by s , of length len . The CRC is returned as an unsigned long.
cyg_crc32
These functions implement a 32 bit CRC by Gary S. Brown. They use the polynomial
X^32+X^26+X^23+X^22+X^16+X^12+X^11+X^10+X^8+X^7+X^5+X^4+X^2+X^1+X^0.
cyg_uint32 cyg_crc32(unsigned char ∗ s, int len);
cyg_uint32 cyg_crc32_accumulate(cyg_uint32 crc, unsigned char ∗ s, int len);
The CRC calculation is run over the data pointed to by s , of length len . The CRC is returned as an unsigned long.
The CRC can be calculated over data separated into multiple buffers by using the function
cyg_crc32_accumulate() . The parameter crc should be the result from the previous CRC calculation.
cyg_ether_crc32
These functions implement the 32 bit CRC used by the Ethernet FCS word.
cyg_uint32 cyg_ether_crc32(unsigned char ∗ s, int len);
cyg_uint32 cyg_ether_crc32_accumulate(cyg_uint32 crc, unsigned char ∗ s, int len);
The CRC calculation is run over the data pointed to by s , of length len . The CRC is returned as an unsigned long.
The CRC can be calculated over data separated into multiple buffers by using the function
cyg_ether_crc32_accumulate() . The parameter crc should be the result from the previous CRC
calculation.
cyg_crc16
This function implements a 16 bit CRC. It uses the polynomial x^16+x^12+x^5+1.
cyg_uint16 cyg_crc16(unsigned char ∗ s, int len);
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