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+>CRC Functions</TITLE
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+>eCos Reference Manual</TH
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+><DIV
+CLASS="CHAPTER"
+><H1
+><A
+NAME="CRC-FUNCTIONS">Chapter 50. CRC Functions</H1
+><DIV
+CLASS="SECT1"
+><H1
+CLASS="SECT1"
+><A
+NAME="SERVICES-CRC-API">CRC API</H1
+><P
+>The package implements a number of CRC functions as described below.
+The API to these functions is in the include file
+<TT
+CLASS="FILENAME"
+>cyg/crc/crc.h</TT
+>.</P
+><DIV
+CLASS="SECT2"
+><H2
+CLASS="SECT2"
+><A
+NAME="SERVICES-CRC-API-CYG-POSIX-CRC32">cyg_posix_crc32</H2
+><P
+>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.</P
+><TABLE
+BORDER="5"
+BGCOLOR="#E0E0F0"
+WIDTH="70%"
+><TR
+><TD
+><PRE
+CLASS="PROGRAMLISTING"
+>cyg_uint32 cyg_posix_crc32(unsigned char * s, int len);</PRE
+></TD
+></TR
+></TABLE
+><P
+>The CRC calculation is run over the data pointed to by
+<TT
+CLASS="PARAMETER"
+><I
+>s</I
+></TT
+>, of length <TT
+CLASS="PARAMETER"
+><I
+>len</I
+></TT
+>. The
+CRC is returned as an unsigned long.</P
+></DIV
+><DIV
+CLASS="SECT2"
+><H2
+CLASS="SECT2"
+><A
+NAME="SERVICES-CRC-API-CYG-CRC32">cyg_crc32</H2
+><P
+>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.</P
+><TABLE
+BORDER="5"
+BGCOLOR="#E0E0F0"
+WIDTH="70%"
+><TR
+><TD
+><PRE
+CLASS="PROGRAMLISTING"
+>cyg_uint32 cyg_crc32(unsigned char * s, int len);
+cyg_uint32 cyg_crc32_accumulate(cyg_uint32 crc, unsigned char * s, int len);</PRE
+></TD
+></TR
+></TABLE
+><P
+>The CRC calculation is run over the data pointed to by
+<TT
+CLASS="PARAMETER"
+><I
+>s</I
+></TT
+>, of length <TT
+CLASS="PARAMETER"
+><I
+>len</I
+></TT
+>. The
+CRC is returned as an unsigned long.</P
+><P
+> The CRC can be calculated over data separated into multiple
+buffers by using the function <TT
+CLASS="PARAMETER"
+><I
+> cyg_crc32_accumulate()</I
+></TT
+>. The parameter <TT
+CLASS="PARAMETER"
+><I
+>crc</I
+></TT
+> should be the
+result from the previous CRC calculation.</P
+></DIV
+><DIV
+CLASS="SECT2"
+><H2
+CLASS="SECT2"
+><A
+NAME="SERVICES-CRC-API-CYG-ETHER-CRC32">cyg_ether_crc32</H2
+><P
+>These functions implement the 32 bit CRC used by the Ethernet FCS word.</P
+><TABLE
+BORDER="5"
+BGCOLOR="#E0E0F0"
+WIDTH="70%"
+><TR
+><TD
+><PRE
+CLASS="PROGRAMLISTING"
+>cyg_uint32 cyg_ether_crc32(unsigned char * s, int len);
+cyg_uint32 cyg_ether_crc32_accumulate(cyg_uint32 crc, unsigned char * s, int len);</PRE
+></TD
+></TR
+></TABLE
+><P
+>The CRC calculation is run over the data pointed to by
+<TT
+CLASS="PARAMETER"
+><I
+>s</I
+></TT
+>, of length <TT
+CLASS="PARAMETER"
+><I
+>len</I
+></TT
+>. The
+CRC is returned as an unsigned long.</P
+><P
+> The CRC can be calculated over data separated into multiple
+buffers by using the function <TT
+CLASS="PARAMETER"
+><I
+> cyg_ether_crc32_accumulate()</I
+></TT
+>. The parameter <TT
+CLASS="PARAMETER"
+><I
+>crc</I
+></TT
+> should be the
+result from the previous CRC calculation.</P
+></DIV
+><DIV
+CLASS="SECT2"
+><H2
+CLASS="SECT2"
+><A
+NAME="SERVICES-CRC-API-CYG-CRC16">cyg_crc16</H2
+><P
+>This function implements a 16 bit CRC. It uses the polynomial
+x^16+x^12+x^5+1.</P
+><TABLE
+BORDER="5"
+BGCOLOR="#E0E0F0"
+WIDTH="70%"
+><TR
+><TD
+><PRE
+CLASS="PROGRAMLISTING"
+>cyg_uint16 cyg_crc16(unsigned char * s, int len);</PRE
+></TD
+></TR
+></TABLE
+><P
+>The CRC calculation is run over the data pointed to by
+<TT
+CLASS="PARAMETER"
+><I
+>s</I
+></TT
+>, of length <TT
+CLASS="PARAMETER"
+><I
+>len</I
+></TT
+>. The
+CRC is returned as an unsigned short.</P
+></DIV
+></DIV
+></DIV
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