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net: iovec checksum calculator 

Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Yan Vugenfirer <yan@daynix.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Dmitry Fleytman 2013-03-09 11:21:03 +02:00 committed by Stefan Hajnoczi
parent 5acf5ea4bc
commit 8402630169
2 changed files with 41 additions and 0 deletions
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12
include/net/checksum.h
View File

@ -38,4 +38,16 @@ net_raw_checksum(uint8_t *data, int length)
return net_checksum_finish(net_checksum_add(length, data));
}
/**
* net_checksum_add_iov: scatter-gather vector checksumming
*
* @iov: input scatter-gather array
* @iov_cnt: number of array elements
* @iov_off: starting iov offset for checksumming
* @size: length of data to be checksummed
*/
uint32_t net_checksum_add_iov(const struct iovec *iov,
const unsigned int iov_cnt,
uint32_t iov_off, uint32_t size);
#endif /* QEMU_NET_CHECKSUM_H */

29
net/checksum.c
View File

@ -15,6 +15,7 @@
* along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu-common.h"
#include "net/checksum.h"
#define PROTO_TCP 6
@ -84,3 +85,31 @@ void net_checksum_calculate(uint8_t *data, int length)
data[14+hlen+csum_offset] = csum >> 8;
data[14+hlen+csum_offset+1] = csum & 0xff;
}
uint32_t
net_checksum_add_iov(const struct iovec *iov, const unsigned int iov_cnt,
uint32_t iov_off, uint32_t size)
{
size_t iovec_off, buf_off;
unsigned int i;
uint32_t res = 0;
uint32_t seq = 0;
iovec_off = 0;
buf_off = 0;
for (i = 0; i < iov_cnt && size; i++) {
if (iov_off < (iovec_off + iov[i].iov_len)) {
size_t len = MIN((iovec_off + iov[i].iov_len) - iov_off , size);
void *chunk_buf = iov[i].iov_base + (iov_off - iovec_off);
res += net_checksum_add_cont(len, chunk_buf, seq);
seq += len;
buf_off += len;
iov_off += len;
size -= len;
}
iovec_off += iov[i].iov_len;
}
return res;
}