diff options
Diffstat (limited to 'src/net/tcpip_if.c')
-rw-r--r-- | src/net/tcpip_if.c | 39 |
1 files changed, 14 insertions, 25 deletions
diff --git a/src/net/tcpip_if.c b/src/net/tcpip_if.c index 5c5e5962..80d69268 100644 --- a/src/net/tcpip_if.c +++ b/src/net/tcpip_if.c @@ -107,30 +107,19 @@ int trans_tx ( struct pk_buff *pkb, struct tcpip_protocol *tcpip, /** * Calculate internet checksum * - * @v data Pointer to the data - * @v len Length of data to be checksummed - * @ret chksum 16 bit internet checksum - * - * This function calculates the internet checksum (refer RFC1071) for "len" - * bytes beginning at the location "data" + * @v b Pointer to the data + * @v len Length of data to be checksummed + * @ret result 16 bit internet checksum */ -uint16_t calc_chksum ( void *data, size_t len ) { - register long sum = 0; - uint16_t checksum; - unsigned short *temp; - while ( len > 1 ) { - temp = (unsigned short*) data++; - sum += *temp; - len -= 2; - } - if ( len > 0 ) { - sum += *(unsigned char *)data; - } - while ( sum >> 16 ) { - sum = ( sum & 0xffff ) + ( sum >> 16 ); - } - checksum = ~sum; - return checksum; +uint16_t calc_chksum(void *b, int len) { + uint16_t *buf = b, result; + uint16_t sum=0; + for ( sum = 0; len > 1; len -= 2 ) /* Sum all 16b words */ + sum += *buf++; + if ( len == 1 ) /* If any stray bytes, */ + sum += *(unsigned char*)buf; /* add to sum */ + sum = (sum >> 16) + (sum & 0xffff); /* Add the carry */ + sum += (sum >> 16); /* (again) */ + result = ~sum; /* Take the one's complement */ + return result; /* Return 16b value */ } - - |