cbb5ba8633
Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de> Acked-by: Stefan Reinauer <stepan@coresystems.de> git-svn-id: svn://svn.coreboot.org/coreboot/trunk@3124 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1
46 lines
1.4 KiB
C
46 lines
1.4 KiB
C
/*****************************************************************************\
|
|
* compute_ip_checksum.c
|
|
* $Id$
|
|
\*****************************************************************************/
|
|
|
|
#include <stdint.h>
|
|
#include "ip_checksum.h"
|
|
|
|
/* Note: The contents of this file were borrowed from the coreboot source
|
|
* code which may be obtained from http://www.coreboot.org.
|
|
* Specifically, this code was obtained from coreboot (LinuxBIOS)
|
|
* version 1.0.0.8.
|
|
*/
|
|
|
|
unsigned long compute_ip_checksum(void *addr, unsigned long length)
|
|
{
|
|
uint8_t *ptr;
|
|
volatile union {
|
|
uint8_t byte[2];
|
|
uint16_t word;
|
|
} value;
|
|
unsigned long sum;
|
|
unsigned long i;
|
|
/* In the most straight forward way possible,
|
|
* compute an ip style checksum.
|
|
*/
|
|
sum = 0;
|
|
ptr = addr;
|
|
for(i = 0; i < length; i++) {
|
|
unsigned long value;
|
|
value = ptr[i];
|
|
if (i & 1) {
|
|
value <<= 8;
|
|
}
|
|
/* Add the new value */
|
|
sum += value;
|
|
/* Wrap around the carry */
|
|
if (sum > 0xFFFF) {
|
|
sum = (sum + (sum >> 16)) & 0xFFFF;
|
|
}
|
|
}
|
|
value.byte[0] = sum & 0xff;
|
|
value.byte[1] = (sum >> 8) & 0xff;
|
|
return (~value.word) & 0xFFFF;
|
|
}
|