mirror/lwip
1
0
Fork 0
mirror of https://github.com/lwip-tcpip/lwip.git synced 2024-12-23 21:14:18 +00:00
Code Issues Packages Projects Releases Wiki Activity

Added some more fixes to the lwip_standard_chksum() comments.

Browse Source
This commit is contained in:
christiaans 2005-12-14 12:55:12 +00:00
parent 5088a38b9f
commit 61cdbb30a6
1 changed files with 7 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
src/core/inet.c
View File

@ -63,7 +63,7 @@
*
* @param dataptr points to start of data to be summed at any boundary
* @param len length of data to be summed
* @return network order (!) lwip checksum (non-inverted Internet sum)
* @return host order (!) lwip checksum (non-inverted Internet sum)
*
* @note accumulator size limits summable lenght to 64k
* @note host endianess is irrelevant (p3 RFC1071)
@ -80,10 +80,11 @@ lwip_standard_chksum(void *dataptr, u16_t len)
octetptr = (u8_t*)dataptr;
while (len > 1)
{
/* first octet is most significant */
/* delacre first octet as most significant
thus assume network order, ignoring host order */
src = (*octetptr) << 8;
octetptr++;
/* second octet is least significant */
/* declare second octet as least significant */
src |= (*octetptr);
octetptr++;
acc += src;
@ -99,7 +100,9 @@ lwip_standard_chksum(void *dataptr, u16_t len)
if ((acc & 0xffff0000) != 0) {
acc = (acc >> 16) + (acc & 0x0000ffffUL);
}
/* caller must invert bits for Internet sum ! */
/* This maybe a little confusing: reorder sum using htons()
instead of ntohs() since it has a little less call overhead.
The caller must invert bits for Internet sum ! */
return htons((u16_t)acc);
}