From 3b178a08efcfb62a8b53c8aa6781e8ab7def6963 Mon Sep 17 00:00:00 2001
From: Kevin Bracey <kevin.bracey@arm.com>
Date: Tue, 21 Mar 2017 11:31:55 +0200
Subject: [PATCH] NSAPI/lwIP: Use netconn_recv_tcp_pbuf

Slight RAM+speed efficiency improvement - read the TCP implementation's
native pbufs, rather than forcing netconn_recv to generate netbuf
wrappers for us. Saves one small lwIP heap allocation per TCP packet
received.
---
 features/lwipstack/LWIPStack.cpp | 10 +++++-----
 features/lwipstack/LWIPStack.h   |  2 +-
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/features/lwipstack/LWIPStack.cpp b/features/lwipstack/LWIPStack.cpp
index 04ca9d59c9..e008826a70 100644
--- a/features/lwipstack/LWIPStack.cpp
+++ b/features/lwipstack/LWIPStack.cpp
@@ -341,7 +341,7 @@ nsapi_error_t LWIP::socket_close(nsapi_socket_t handle)
         _event_flag.wait_any(TCP_CLOSED_FLAG, TCP_CLOSE_TIMEOUT);
     }
 #endif
-    netbuf_delete(s->buf);
+    pbuf_free(s->buf);
     err_t err = netconn_delete(s->conn);
     arena_dealloc(s);
     return err_remap(err);
@@ -465,7 +465,7 @@ nsapi_size_or_error_t LWIP::socket_recv(nsapi_socket_t handle, void *data, nsapi
     struct mbed_lwip_socket *s = (struct mbed_lwip_socket *)handle;
 
     if (!s->buf) {
-        err_t err = netconn_recv(s->conn, &s->buf);
+        err_t err = netconn_recv_tcp_pbuf(s->conn, &s->buf);
         s->offset = 0;
 
         if (err != ERR_OK) {
@@ -473,11 +473,11 @@ nsapi_size_or_error_t LWIP::socket_recv(nsapi_socket_t handle, void *data, nsapi
         }
     }
 
-    u16_t recv = netbuf_copy_partial(s->buf, data, (u16_t)size, s->offset);
+    u16_t recv = pbuf_copy_partial(s->buf, data, (u16_t)size, s->offset);
     s->offset += recv;
 
-    if (s->offset >= netbuf_len(s->buf)) {
-        netbuf_delete(s->buf);
+    if (s->offset >= s->buf->tot_len) {
+        pbuf_free(s->buf);
         s->buf = 0;
     }
 
diff --git a/features/lwipstack/LWIPStack.h b/features/lwipstack/LWIPStack.h
index 00c32bea6a..a9b85cc7f6 100644
--- a/features/lwipstack/LWIPStack.h
+++ b/features/lwipstack/LWIPStack.h
@@ -526,7 +526,7 @@ private:
         bool in_use;
 
         struct netconn *conn;
-        struct netbuf *buf;
+        struct pbuf *buf;
         u16_t offset;
 
         void (*cb)(void *);