[Qemu-devel] [PATCH v9 2/5] Adding utility function net_checksum_add_iov() for iovec checksum calculation

[Dmitry Fleytman <dmitry@daynix.com>]

Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
Signed-off-by: Yan Vugenfirer <yan@daynix.com>
---
 include/net/checksum.h |  8 ++++++++
 net/checksum.c         | 28 ++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/include/net/checksum.h b/include/net/checksum.h
index 171924c..289c16c 100644
--- a/include/net/checksum.h
+++ b/include/net/checksum.h
@@ -19,6 +19,7 @@
 #define QEMU_NET_CHECKSUM_H
 
 #include <stdint.h>
+#include "qemu-common.h"
 
 uint32_t net_checksum_add_cont(int len, uint8_t *buf, int seq);
 uint16_t net_checksum_finish(uint32_t sum);
@@ -38,4 +39,11 @@ net_raw_checksum(uint8_t *data, int length)
   return net_checksum_finish(net_checksum_add(length, data));
 }
 
+/**
+ * Checksum calculation for scatter-gather vector
+ */
+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 */
diff --git a/net/checksum.c b/net/checksum.c
index 4fa5563..9c813ff 100644
--- a/net/checksum.c
+++ b/net/checksum.c
@@ -84,3 +84,31 @@ 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;
+}
-- 
1.7.11.7