Starting to move thte library

inc/legacy/modbus-tcp-private.h

@@ -0,0 +1,41 @@
+/*
+ * Copyright © Stéphane Raimbault <stephane.raimbault@gmail.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ */
+
+#ifndef MODBUS_TCP_PRIVATE_H
+#define MODBUS_TCP_PRIVATE_H
+
+#define _MODBUS_TCP_HEADER_LENGTH     7
+#define _MODBUS_TCP_PRESET_REQ_LENGTH 12
+#define _MODBUS_TCP_PRESET_RSP_LENGTH 8
+
+#define _MODBUS_TCP_CHECKSUM_LENGTH 0
+
+/* In both structures, the transaction ID must be placed on first position
+   to have a quick access not dependent of the TCP backend */
+typedef struct _modbus_tcp {
+    /* Extract from MODBUS Messaging on TCP/IP Implementation Guide V1.0b
+       (page 23/46):
+       The transaction identifier is used to associate the future response
+       with the request. This identifier is unique on each TCP connection. */
+    uint16_t t_id;
+    /* TCP port */
+    int port;
+    /* IP address */
+    char ip[16];
+} modbus_tcp_t;
+
+typedef struct _modbus_tcp_pi {
+    /* Transaction ID */
+    uint16_t t_id;
+    /* TCP port */
+    int port;
+    /* Node */
+    char *node;
+    /* Service */
+    char *service;
+} modbus_tcp_pi_t;
+
+#endif /* MODBUS_TCP_PRIVATE_H */