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From 2d7d80e8dc160904fa7276cc05da26c062a50066 Mon Sep 17 00:00:00 2001
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From: Stefan Hajnoczi <stefanha@redhat.com>
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Date: Wed, 15 Jul 2015 18:16:59 +0100
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Subject: [PATCH 2/7] rtl8139: drop tautologous if (ip) {...} statement
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The previous patch stopped using the ip pointer as an indicator that the
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IP header is present.  When we reach the if (ip) {...} statement we know
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ip is always non-NULL.
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Remove the if statement to reduce nesting.
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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---
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 hw/net/rtl8139.c | 305 +++++++++++++++++++++++++++----------------------------
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 1 file changed, 151 insertions(+), 154 deletions(-)
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diff --git a/tools/qemu-xen/hw/net/rtl8139.c b/tools/qemu-xen/hw/net/rtl8139.c
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index 91ba33b..2f12d42 100644
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--- a/tools/qemu-xen/hw/net/rtl8139.c
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+++ b/tools/qemu-xen/hw/net/rtl8139.c
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@@ -2198,198 +2198,195 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s)
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             ip_protocol = ip->ip_p;
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             ip_data_len = be16_to_cpu(ip->ip_len) - hlen;
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-            if (ip)
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+            if (txdw0 & CP_TX_IPCS)
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             {
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-                if (txdw0 & CP_TX_IPCS)
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-                {
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-                    DPRINTF("+++ C+ mode need IP checksum\n");
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+                DPRINTF("+++ C+ mode need IP checksum\n");
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-                    if (hlen<sizeof(ip_header) || hlen>eth_payload_len) {/* min header length */
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-                        /* bad packet header len */
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-                        /* or packet too short */
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-                    }
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-                    else
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-                    {
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-                        ip->ip_sum = 0;
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-                        ip->ip_sum = ip_checksum(ip, hlen);
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-                        DPRINTF("+++ C+ mode IP header len=%d checksum=%04x\n",
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-                            hlen, ip->ip_sum);
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-                    }
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+                if (hlen<sizeof(ip_header) || hlen>eth_payload_len) {/* min header length */
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+                    /* bad packet header len */
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+                    /* or packet too short */
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                 }
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-
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-                if ((txdw0 & CP_TX_LGSEN) && ip_protocol == IP_PROTO_TCP)
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+                else
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                 {
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-                    int large_send_mss = (txdw0 >> 16) & CP_TC_LGSEN_MSS_MASK;
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+                    ip->ip_sum = 0;
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+                    ip->ip_sum = ip_checksum(ip, hlen);
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+                    DPRINTF("+++ C+ mode IP header len=%d checksum=%04x\n",
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+                        hlen, ip->ip_sum);
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+                }
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+            }
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-                    DPRINTF("+++ C+ mode offloaded task TSO MTU=%d IP data %d "
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-                        "frame data %d specified MSS=%d\n", ETH_MTU,
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-                        ip_data_len, saved_size - ETH_HLEN, large_send_mss);
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+            if ((txdw0 & CP_TX_LGSEN) && ip_protocol == IP_PROTO_TCP)
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+            {
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+                int large_send_mss = (txdw0 >> 16) & CP_TC_LGSEN_MSS_MASK;
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-                    int tcp_send_offset = 0;
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-                    int send_count = 0;
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+                DPRINTF("+++ C+ mode offloaded task TSO MTU=%d IP data %d "
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+                    "frame data %d specified MSS=%d\n", ETH_MTU,
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+                    ip_data_len, saved_size - ETH_HLEN, large_send_mss);
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-                    /* maximum IP header length is 60 bytes */
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-                    uint8_t saved_ip_header[60];
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+                int tcp_send_offset = 0;
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+                int send_count = 0;
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-                    /* save IP header template; data area is used in tcp checksum calculation */
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-                    memcpy(saved_ip_header, eth_payload_data, hlen);
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+                /* maximum IP header length is 60 bytes */
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+                uint8_t saved_ip_header[60];
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-                    /* a placeholder for checksum calculation routine in tcp case */
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-                    uint8_t *data_to_checksum     = eth_payload_data + hlen - 12;
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-                    //                    size_t   data_to_checksum_len = eth_payload_len  - hlen + 12;
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+                /* save IP header template; data area is used in tcp checksum calculation */
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+                memcpy(saved_ip_header, eth_payload_data, hlen);
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-                    /* pointer to TCP header */
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-                    tcp_header *p_tcp_hdr = (tcp_header*)(eth_payload_data + hlen);
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+                /* a placeholder for checksum calculation routine in tcp case */
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+                uint8_t *data_to_checksum     = eth_payload_data + hlen - 12;
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+                //                    size_t   data_to_checksum_len = eth_payload_len  - hlen + 12;
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-                    int tcp_hlen = TCP_HEADER_DATA_OFFSET(p_tcp_hdr);
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+                /* pointer to TCP header */
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+                tcp_header *p_tcp_hdr = (tcp_header*)(eth_payload_data + hlen);
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-                    /* ETH_MTU = ip header len + tcp header len + payload */
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-                    int tcp_data_len = ip_data_len - tcp_hlen;
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-                    int tcp_chunk_size = ETH_MTU - hlen - tcp_hlen;
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+                int tcp_hlen = TCP_HEADER_DATA_OFFSET(p_tcp_hdr);
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-                    DPRINTF("+++ C+ mode TSO IP data len %d TCP hlen %d TCP "
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-                        "data len %d TCP chunk size %d\n", ip_data_len,
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-                        tcp_hlen, tcp_data_len, tcp_chunk_size);
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+                /* ETH_MTU = ip header len + tcp header len + payload */
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+                int tcp_data_len = ip_data_len - tcp_hlen;
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+                int tcp_chunk_size = ETH_MTU - hlen - tcp_hlen;
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-                    /* note the cycle below overwrites IP header data,
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-                       but restores it from saved_ip_header before sending packet */
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+                DPRINTF("+++ C+ mode TSO IP data len %d TCP hlen %d TCP "
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+                    "data len %d TCP chunk size %d\n", ip_data_len,
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+                    tcp_hlen, tcp_data_len, tcp_chunk_size);
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-                    int is_last_frame = 0;
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+                /* note the cycle below overwrites IP header data,
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+                   but restores it from saved_ip_header before sending packet */
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-                    for (tcp_send_offset = 0; tcp_send_offset < tcp_data_len; tcp_send_offset += tcp_chunk_size)
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-                    {
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-                        uint16_t chunk_size = tcp_chunk_size;
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-
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-                        /* check if this is the last frame */
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-                        if (tcp_send_offset + tcp_chunk_size >= tcp_data_len)
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-                        {
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-                            is_last_frame = 1;
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-                            chunk_size = tcp_data_len - tcp_send_offset;
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-                        }
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-
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-                        DPRINTF("+++ C+ mode TSO TCP seqno %08x\n",
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-                            be32_to_cpu(p_tcp_hdr->th_seq));
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-
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-                        /* add 4 TCP pseudoheader fields */
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-                        /* copy IP source and destination fields */
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-                        memcpy(data_to_checksum, saved_ip_header + 12, 8);
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-
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-                        DPRINTF("+++ C+ mode TSO calculating TCP checksum for "
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-                            "packet with %d bytes data\n", tcp_hlen +
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-                            chunk_size);
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-
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-                        if (tcp_send_offset)
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-                        {
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-                            memcpy((uint8_t*)p_tcp_hdr + tcp_hlen, (uint8_t*)p_tcp_hdr + tcp_hlen + tcp_send_offset, chunk_size);
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-                        }
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-
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-                        /* keep PUSH and FIN flags only for the last frame */
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-                        if (!is_last_frame)
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-                        {
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-                            TCP_HEADER_CLEAR_FLAGS(p_tcp_hdr, TCP_FLAG_PUSH|TCP_FLAG_FIN);
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-                        }
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-
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-                        /* recalculate TCP checksum */
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-                        ip_pseudo_header *p_tcpip_hdr = (ip_pseudo_header *)data_to_checksum;
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-                        p_tcpip_hdr->zeros      = 0;
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-                        p_tcpip_hdr->ip_proto   = IP_PROTO_TCP;
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-                        p_tcpip_hdr->ip_payload = cpu_to_be16(tcp_hlen + chunk_size);
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-
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-                        p_tcp_hdr->th_sum = 0;
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-
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-                        int tcp_checksum = ip_checksum(data_to_checksum, tcp_hlen + chunk_size + 12);
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-                        DPRINTF("+++ C+ mode TSO TCP checksum %04x\n",
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-                            tcp_checksum);
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-
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-                        p_tcp_hdr->th_sum = tcp_checksum;
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-
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-                        /* restore IP header */
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-                        memcpy(eth_payload_data, saved_ip_header, hlen);
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-
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-                        /* set IP data length and recalculate IP checksum */
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-                        ip->ip_len = cpu_to_be16(hlen + tcp_hlen + chunk_size);
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-
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-                        /* increment IP id for subsequent frames */
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-                        ip->ip_id = cpu_to_be16(tcp_send_offset/tcp_chunk_size + be16_to_cpu(ip->ip_id));
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-
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-                        ip->ip_sum = 0;
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-                        ip->ip_sum = ip_checksum(eth_payload_data, hlen);
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-                        DPRINTF("+++ C+ mode TSO IP header len=%d "
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-                            "checksum=%04x\n", hlen, ip->ip_sum);
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-
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-                        int tso_send_size = ETH_HLEN + hlen + tcp_hlen + chunk_size;
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-                        DPRINTF("+++ C+ mode TSO transferring packet size "
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-                            "%d\n", tso_send_size);
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-                        rtl8139_transfer_frame(s, saved_buffer, tso_send_size,
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-                            0, (uint8_t *) dot1q_buffer);
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-
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-                        /* add transferred count to TCP sequence number */
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-                        p_tcp_hdr->th_seq = cpu_to_be32(chunk_size + be32_to_cpu(p_tcp_hdr->th_seq));
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-                        ++send_count;
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-                    }
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+                int is_last_frame = 0;
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-                    /* Stop sending this frame */
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-                    saved_size = 0;
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-                }
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-                else if (txdw0 & (CP_TX_TCPCS|CP_TX_UDPCS))
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+                for (tcp_send_offset = 0; tcp_send_offset < tcp_data_len; tcp_send_offset += tcp_chunk_size)
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                 {
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-                    DPRINTF("+++ C+ mode need TCP or UDP checksum\n");
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+                    uint16_t chunk_size = tcp_chunk_size;
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-                    /* maximum IP header length is 60 bytes */
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-                    uint8_t saved_ip_header[60];
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-                    memcpy(saved_ip_header, eth_payload_data, hlen);
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+                    /* check if this is the last frame */
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+                    if (tcp_send_offset + tcp_chunk_size >= tcp_data_len)
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+                    {
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+                        is_last_frame = 1;
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+                        chunk_size = tcp_data_len - tcp_send_offset;
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+                    }
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-                    uint8_t *data_to_checksum     = eth_payload_data + hlen - 12;
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-                    //                    size_t   data_to_checksum_len = eth_payload_len  - hlen + 12;
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+                    DPRINTF("+++ C+ mode TSO TCP seqno %08x\n",
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+                        be32_to_cpu(p_tcp_hdr->th_seq));
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                     /* add 4 TCP pseudoheader fields */
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                     /* copy IP source and destination fields */
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                     memcpy(data_to_checksum, saved_ip_header + 12, 8);
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-                    if ((txdw0 & CP_TX_TCPCS) && ip_protocol == IP_PROTO_TCP)
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+                    DPRINTF("+++ C+ mode TSO calculating TCP checksum for "
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+                        "packet with %d bytes data\n", tcp_hlen +
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+                        chunk_size);
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+
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+                    if (tcp_send_offset)
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                     {
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-                        DPRINTF("+++ C+ mode calculating TCP checksum for "
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-                            "packet with %d bytes data\n", ip_data_len);
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+                        memcpy((uint8_t*)p_tcp_hdr + tcp_hlen, (uint8_t*)p_tcp_hdr + tcp_hlen + tcp_send_offset, chunk_size);
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+                    }
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-                        ip_pseudo_header *p_tcpip_hdr = (ip_pseudo_header *)data_to_checksum;
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-                        p_tcpip_hdr->zeros      = 0;
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-                        p_tcpip_hdr->ip_proto   = IP_PROTO_TCP;
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-                        p_tcpip_hdr->ip_payload = cpu_to_be16(ip_data_len);
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+                    /* keep PUSH and FIN flags only for the last frame */
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+                    if (!is_last_frame)
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+                    {
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+                        TCP_HEADER_CLEAR_FLAGS(p_tcp_hdr, TCP_FLAG_PUSH|TCP_FLAG_FIN);
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+                    }
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-                        tcp_header* p_tcp_hdr = (tcp_header *) (data_to_checksum+12);
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+                    /* recalculate TCP checksum */
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+                    ip_pseudo_header *p_tcpip_hdr = (ip_pseudo_header *)data_to_checksum;
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+                    p_tcpip_hdr->zeros      = 0;
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+                    p_tcpip_hdr->ip_proto   = IP_PROTO_TCP;
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+                    p_tcpip_hdr->ip_payload = cpu_to_be16(tcp_hlen + chunk_size);
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-                        p_tcp_hdr->th_sum = 0;
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+                    p_tcp_hdr->th_sum = 0;
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-                        int tcp_checksum = ip_checksum(data_to_checksum, ip_data_len + 12);
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-                        DPRINTF("+++ C+ mode TCP checksum %04x\n",
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-                            tcp_checksum);
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+                    int tcp_checksum = ip_checksum(data_to_checksum, tcp_hlen + chunk_size + 12);
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+                    DPRINTF("+++ C+ mode TSO TCP checksum %04x\n",
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+                        tcp_checksum);
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-                        p_tcp_hdr->th_sum = tcp_checksum;
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-                    }
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-                    else if ((txdw0 & CP_TX_UDPCS) && ip_protocol == IP_PROTO_UDP)
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-                    {
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-                        DPRINTF("+++ C+ mode calculating UDP checksum for "
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-                            "packet with %d bytes data\n", ip_data_len);
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+                    p_tcp_hdr->th_sum = tcp_checksum;
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-                        ip_pseudo_header *p_udpip_hdr = (ip_pseudo_header *)data_to_checksum;
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-                        p_udpip_hdr->zeros      = 0;
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-                        p_udpip_hdr->ip_proto   = IP_PROTO_UDP;
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-                        p_udpip_hdr->ip_payload = cpu_to_be16(ip_data_len);
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+                    /* restore IP header */
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+                    memcpy(eth_payload_data, saved_ip_header, hlen);
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-                        udp_header *p_udp_hdr = (udp_header *) (data_to_checksum+12);
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+                    /* set IP data length and recalculate IP checksum */
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+                    ip->ip_len = cpu_to_be16(hlen + tcp_hlen + chunk_size);
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-                        p_udp_hdr->uh_sum = 0;
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+                    /* increment IP id for subsequent frames */
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+                    ip->ip_id = cpu_to_be16(tcp_send_offset/tcp_chunk_size + be16_to_cpu(ip->ip_id));
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-                        int udp_checksum = ip_checksum(data_to_checksum, ip_data_len + 12);
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-                        DPRINTF("+++ C+ mode UDP checksum %04x\n",
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-                            udp_checksum);
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+                    ip->ip_sum = 0;
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+                    ip->ip_sum = ip_checksum(eth_payload_data, hlen);
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+                    DPRINTF("+++ C+ mode TSO IP header len=%d "
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+                        "checksum=%04x\n", hlen, ip->ip_sum);
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-                        p_udp_hdr->uh_sum = udp_checksum;
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-                    }
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+                    int tso_send_size = ETH_HLEN + hlen + tcp_hlen + chunk_size;
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+                    DPRINTF("+++ C+ mode TSO transferring packet size "
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+                        "%d\n", tso_send_size);
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+                    rtl8139_transfer_frame(s, saved_buffer, tso_send_size,
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+                        0, (uint8_t *) dot1q_buffer);
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-                    /* restore IP header */
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-                    memcpy(eth_payload_data, saved_ip_header, hlen);
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+                    /* add transferred count to TCP sequence number */
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+                    p_tcp_hdr->th_seq = cpu_to_be32(chunk_size + be32_to_cpu(p_tcp_hdr->th_seq));
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+                    ++send_count;
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                 }
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+
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+                /* Stop sending this frame */
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+                saved_size = 0;
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+            }
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+            else if (txdw0 & (CP_TX_TCPCS|CP_TX_UDPCS))
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+            {
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+                DPRINTF("+++ C+ mode need TCP or UDP checksum\n");
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+
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+                /* maximum IP header length is 60 bytes */
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+                uint8_t saved_ip_header[60];
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+                memcpy(saved_ip_header, eth_payload_data, hlen);
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+
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+                uint8_t *data_to_checksum     = eth_payload_data + hlen - 12;
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+                //                    size_t   data_to_checksum_len = eth_payload_len  - hlen + 12;
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+
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+                /* add 4 TCP pseudoheader fields */
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+                /* copy IP source and destination fields */
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+                memcpy(data_to_checksum, saved_ip_header + 12, 8);
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+
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+                if ((txdw0 & CP_TX_TCPCS) && ip_protocol == IP_PROTO_TCP)
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+                {
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+                    DPRINTF("+++ C+ mode calculating TCP checksum for "
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+                        "packet with %d bytes data\n", ip_data_len);
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+
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+                    ip_pseudo_header *p_tcpip_hdr = (ip_pseudo_header *)data_to_checksum;
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+                    p_tcpip_hdr->zeros      = 0;
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+                    p_tcpip_hdr->ip_proto   = IP_PROTO_TCP;
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+                    p_tcpip_hdr->ip_payload = cpu_to_be16(ip_data_len);
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+
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+                    tcp_header* p_tcp_hdr = (tcp_header *) (data_to_checksum+12);
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+
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+                    p_tcp_hdr->th_sum = 0;
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+
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+                    int tcp_checksum = ip_checksum(data_to_checksum, ip_data_len + 12);
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+                    DPRINTF("+++ C+ mode TCP checksum %04x\n",
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+                        tcp_checksum);
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+
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+                    p_tcp_hdr->th_sum = tcp_checksum;
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+                }
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+                else if ((txdw0 & CP_TX_UDPCS) && ip_protocol == IP_PROTO_UDP)
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+                {
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+                    DPRINTF("+++ C+ mode calculating UDP checksum for "
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+                        "packet with %d bytes data\n", ip_data_len);
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+
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+                    ip_pseudo_header *p_udpip_hdr = (ip_pseudo_header *)data_to_checksum;
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+                    p_udpip_hdr->zeros      = 0;
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+                    p_udpip_hdr->ip_proto   = IP_PROTO_UDP;
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+                    p_udpip_hdr->ip_payload = cpu_to_be16(ip_data_len);
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+
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+                    udp_header *p_udp_hdr = (udp_header *) (data_to_checksum+12);
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+
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+                    p_udp_hdr->uh_sum = 0;
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+
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+                    int udp_checksum = ip_checksum(data_to_checksum, ip_data_len + 12);
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+                    DPRINTF("+++ C+ mode UDP checksum %04x\n",
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+                        udp_checksum);
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+
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+                    p_udp_hdr->uh_sum = udp_checksum;
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+                }
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+
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+                /* restore IP header */
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+                memcpy(eth_payload_data, saved_ip_header, hlen);
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             }
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         }
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-- 
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2.1.4
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