[Qemu-devel] [PATCH 3/7 V6] Adding utility function iov_net_csum_add() for iovec checksum calculation Adding utility function iov_rebuild() for smart iovec copy

[Dmitry Fleytman]

From: Dmitry Fleytman <address@hidden>

Signed-off-by: Dmitry Fleytman <address@hidden>
Signed-off-by: Yan Vugenfirer <address@hidden>
---
 iov.c |   53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 iov.h |    6 ++++++
 2 files changed, 59 insertions(+), 0 deletions(-)

diff --git a/iov.c b/iov.c
index 0f96493..0ac15a1 100644
--- a/iov.c
+++ b/iov.c
@@ -16,6 +16,7 @@
  */
 
 #include "iov.h"
+#include "net/checksum.h"
 
 size_t iov_from_buf(struct iovec *iov, unsigned int iov_cnt,
                     const void *buf, size_t iov_off, size_t size)
@@ -65,6 +66,30 @@ size_t iov_to_buf(const struct iovec *iov, const unsigned 
int iov_cnt,
     return buf_off;
 }
 
+size_t iov_rebuild(struct iovec *dst, unsigned int dst_cnt,
+                   const struct iovec *src, const unsigned int src_cnt,
+                   size_t src_off)
+{
+    size_t curr_src_off = 0;
+    unsigned int i, j = 0;
+
+    for (i = 0; i < src_cnt; i++) {
+        if (src_off < (curr_src_off + src[i].iov_len)) {
+            if (j == dst_cnt) {
+                return (size_t) -1;
+            }
+
+            dst[j].iov_len = curr_src_off + src[i].iov_len - src_off;
+            dst[j].iov_base = src[i].iov_base + (src_off - curr_src_off);
+
+            src_off += dst[j].iov_len;
+            j++;
+        }
+        curr_src_off += src[i].iov_len;
+    }
+    return j;
+}
+
 size_t iov_clear(const struct iovec *iov, const unsigned int iov_cnt,
                  size_t iov_off, size_t size)
 {
@@ -130,3 +155,31 @@ void iov_hexdump(const struct iovec *iov, const unsigned 
int iov_cnt,
         fprintf(fp, "\n");
     }
 }
+
+uint32_t
+iov_net_csum_add(const struct iovec *iov, const unsigned int iov_cnt,
+                 size_t iov_off, size_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;
+}
diff --git a/iov.h b/iov.h
index 94d2f78..b11cdd3 100644
--- a/iov.h
+++ b/iov.h
@@ -16,8 +16,14 @@ size_t iov_from_buf(struct iovec *iov, unsigned int iov_cnt,
                     const void *buf, size_t iov_off, size_t size);
 size_t iov_to_buf(const struct iovec *iov, const unsigned int iov_cnt,
                   void *buf, size_t iov_off, size_t size);
+size_t iov_rebuild(struct iovec *dest, unsigned int dest_cnt,
+                   const struct iovec *src, const unsigned int src_cnt,
+                   size_t src_off);
 size_t iov_size(const struct iovec *iov, const unsigned int iov_cnt);
 size_t iov_clear(const struct iovec *iov, const unsigned int iov_cnt,
                  size_t iov_off, size_t size);
 void iov_hexdump(const struct iovec *iov, const unsigned int iov_cnt,
                  FILE *fp, const char *prefix, size_t limit);
+uint32_t
+iov_net_csum_add(const struct iovec *iov, const unsigned int iov_cnt,
+                 size_t iov_off, size_t size);
-- 
1.7.7.6