OSD-GDB server: Adds following features

(1) Connect to GDB over TCP
(2) Send and Recieve data to/from the client
(3) Receive RSP packet from the client
(4) Validate the obtained packet using checksum
(5) Send RSP packet to the client

Author: shivmgg

src/libosd/include/osd/osd_gdbserver.h

@@ -0,0 +1,123 @@
+/* Copyright 2018 The Open SoC Debug Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef OSD_GDBSERVER_H
+#define OSD_GDBSERVER_H
+
+#include <osd/hostmod.h>
+#include <osd/osd.h>
+
+#include <stdlib.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @defgroup libosd-gdbserver OSD-GDB server utility
+ * @ingroup libosd
+ *
+ * @{
+ */
+
+struct connection;
+
+/**
+ * Connect GDB server with GDB
+ *
+ * @return OSD_OK on success, any other value indicates an error
+ */
+osd_result add_connection(char *name, char *port);
+
+/**
+ * Read a character from the obtained buffer
+ */
+osd_result get_char(struct connection *c, int client_fd, int *ch);
+
+/**
+ * Read data from the GDB client
+ *
+ * @param c the connection object
+ * @param client_fd the client_fd of the GDB
+ *
+ * @return OSD_OK on success, any other value indicates an error
+ *
+ * @see put_data()
+ */
+osd_result get_data(struct connection *c, int client_fd);
+
+/**
+ * Write data to the GDB client
+ *
+ * @param c the connection object
+ * @param client_fd the client_fd of the GDB
+ * @param data the data to write to the connected client
+ * @param len the length of the data to be written
+ * @return OSD_OK on success, any other value indicates an error
+ *
+ * @see get_data()
+ */
+osd_result put_data(struct connection *c, int client_fd, char *data, int len);
+
+/**
+ *
+ * Get the packet-data from obtained buffer $<packet-data>#<checksum>
+ *
+ * @param c the connection object
+ * @param client_fd the client_fd of the GDB
+ * @param buffer the packet-data obtained from the connected client
+ * @param len the length of the packet-data
+ * @return OSD_OK on success, any other value indicates an error
+ *
+ * @see put_packet()
+ */
+osd_result get_packet(struct connection *c, int client_fd, char *buffer,
+                      int *len);
+
+/**
+ * Verify the checksum of obtained packet
+ *
+ * @param c the connection object
+ * @param client_fd the client_fd of the GDB
+ * @param ver_checksum indicates if the obtained checksum is correct or not
+ * @param buffer the packet-data obtained from the connected client
+ * @param len the length of the packet-data
+ * @return OSD_OK on success, any other value indicates an error
+ */
+osd_result validate_packet(struct connection *c, int client_fd,
+                           bool *ver_checksum, int *len, char *buffer);
+
+/**
+ *
+ * Send the packet-data to the buffer $<packet-data>#<checksum>
+ *
+ * @param c the connection object
+ * @param client_fd the client_fd of the GDB
+ * @param buffer the packet-data to send to the connected client
+ * @param len the length of the packet-data
+ * @return OSD_OK on success, any other value indicates an error
+ *
+ * @see get_packet()
+ */
+osd_result put_packet(struct connection *c, int client_fd, char *buffer,
+                      int len);
+
+/**@}*/ /* end of doxygen group libosd-gdbserver */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif  // OSD_GDBSERVER_H