ONE_CSUM(3)               Minix Programmer's Manual                ONE_CSUM(3)


NAME
     oneC_sum - One's complement internet checksum

SYNOPSIS
     #define _MINIX_SOURCE 1
     #include <stddef.h>
     #include <sys/types.h>

     #include <net/gen/oneCsum.h>

     u16_t oneC_sum(u16_t prev, u16_t *data, size_t size)

DESCRIPTION
     OneC_sum is used to calculate the one's complement checksum needed for IP
     network packets.  A good document about the Internet Checksum is RFC-1071
     (Computing the Internet checksum).

     One_Csum expects three parameters:

     prev      The checksum of previous blocks of data that are to be included
               in  the  checksum.  The value of prev in first call to oneC_sum
               should be 0.

     data      A pointer to the block of data.  The data is interpreted  as  a
               series  of  16  bit  numbers  in network byte order, but an odd
               number of bytes is also allowed.

     size      The size of the data in bytes.

SEE ALSO
     ip(4).
     RFC-1071

AUTHOR
     Philip Homburg (philip@cs.vu.nl)























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