New *_create() APIs

Author: debevv

README.md

@@ -1,6 +1,7 @@
 # nanoMODBUS - A compact MODBUS RTU/TCP C library for embedded/microcontrollers
 
-**If you found this library useful, buy me a coffee on** [<img src='https://storage.ko-fi.com/cdn/brandasset/logo_white_stroke.png' width='80'>](https://ko-fi.com/B0B2LK779)
+**If you found this library useful, buy me a coffee on
+** [<img src='https://storage.ko-fi.com/cdn/brandasset/logo_white_stroke.png' width='80'>](https://ko-fi.com/B0B2LK779)
 
 nanoMODBUS is a small C library that implements the Modbus protocol. It is especially useful in embedded and
 resource-constrained systems like microcontrollers.  
@@ -52,6 +53,7 @@ int main(int argc, char* argv[]) {
 
     // my_transport_read() and my_transport_write() are implemented by the user 
     nmbs_platform_conf platform_conf;
+    nmbs_platform_conf_create(&platform_conf);
     platform_conf.transport = NMBS_TRANSPORT_TCP;
     platform_conf.read = my_transport_read;
     platform_conf.write = my_transport_write;

examples/arduino/client-rtu/client-rtu.ino

@@ -42,6 +42,7 @@ void setup() {
 
 void loop() {
   nmbs_platform_conf platform_conf;
+  nmbs_platform_conf_create(&platform_conf);
   platform_conf.transport = NMBS_TRANSPORT_RTU;
   platform_conf.read = read_serial;
   platform_conf.write = write_serial;

examples/arduino/server-rtu/server-rtu.ino

@@ -103,12 +103,14 @@ void setup() {
 
 void loop() {
   nmbs_platform_conf platform_conf;
+  nmbs_platform_conf_create(&platform_conf);
   platform_conf.transport = NMBS_TRANSPORT_RTU;
   platform_conf.read = read_serial;
   platform_conf.write = write_serial;
   platform_conf.arg = NULL;
 
-  nmbs_callbacks callbacks = {0};
+  nmbs_callbacks callbacks;
+  nmbs_callbacks_create(&callbacks);
   callbacks.read_coils = handle_read_coils;
   callbacks.write_multiple_coils = handle_write_multiple_coils;
   callbacks.read_holding_registers = handler_read_holding_registers;

examples/linux/client-tcp.c

@@ -26,6 +26,7 @@ int main(int argc, char* argv[]) {
     }
 
     nmbs_platform_conf platform_conf;
+    nmbs_platform_conf_create(&platform_conf);
     platform_conf.transport = NMBS_TRANSPORT_TCP;
     platform_conf.read = read_fd_linux;
     platform_conf.write = write_fd_linux;

examples/linux/server-tcp.c

@@ -182,13 +182,15 @@ int main(int argc, char* argv[]) {
         return 1;
     }
 
-    nmbs_platform_conf platform_conf = {0};
+    nmbs_platform_conf platform_conf;
+    nmbs_platform_conf_create(&platform_conf);
     platform_conf.transport = NMBS_TRANSPORT_TCP;
     platform_conf.read = read_fd_linux;
     platform_conf.write = write_fd_linux;
     platform_conf.arg = NULL;    // We will set the arg (socket fd) later
 
-    nmbs_callbacks callbacks = {0};
+    nmbs_callbacks callbacks;
+    nmbs_callbacks_create(&callbacks);
     callbacks.read_coils = handle_read_coils;
     callbacks.write_multiple_coils = handle_write_multiple_coils;
     callbacks.read_holding_registers = handler_read_holding_registers;

examples/win32/modbus_cli.c

@@ -47,6 +47,7 @@ void onError(nmbs_error err) {
 void ReadRegister(uint16_t reg) {
 
     nmbs_platform_conf platform_conf;
+    nmbs_platform_conf_create(&platform_conf);
     platform_conf.transport = NMBS_TRANSPORT_RTU;
     platform_conf.read = read_serial;
     platform_conf.write = write_serial;

nanomodbus.c

@@ -30,6 +30,8 @@
 #include <stdint.h>
 #include <string.h>
 
+#define NMBS_UNUSED_PARAM(x) ((x) = (x))
+
 #ifdef NMBS_DEBUG
 #include <stdio.h>
 #define NMBS_DEBUG_PRINT(...) printf(__VA_ARGS__)
@@ -178,7 +180,7 @@ nmbs_error nmbs_create(nmbs_t* nmbs, const nmbs_platform_conf* platform_conf) {
     nmbs->byte_timeout_ms = -1;
     nmbs->read_timeout_ms = -1;
 
-    if (!platform_conf)
+    if (!platform_conf || platform_conf->initialized != 0xFFFFDEBE)
         return NMBS_ERROR_INVALID_ARGUMENT;
 
     if (platform_conf->transport != NMBS_TRANSPORT_RTU && platform_conf->transport != NMBS_TRANSPORT_TCP)
@@ -203,6 +205,14 @@ void nmbs_set_byte_timeout(nmbs_t* nmbs, int32_t timeout_ms) {
 }
 
 
+void nmbs_platform_conf_create(nmbs_platform_conf* platform_conf) {
+    memset(platform_conf, 0, sizeof(nmbs_platform_conf));
+    platform_conf->crc_calc = nmbs_crc_calc;
+    // Workaround for older user code not calling nmbs_platform_conf_create()
+    platform_conf->initialized = 0xFFFFDEBE;
+}
+
+
 void nmbs_set_destination_rtu_address(nmbs_t* nmbs, uint8_t address) {
     nmbs->dest_address_rtu = address;
 }
@@ -213,7 +223,8 @@ void nmbs_set_platform_arg(nmbs_t* nmbs, void* arg) {
 }
 
 
-uint16_t nmbs_crc_calc(const uint8_t* data, uint32_t length) {
+uint16_t nmbs_crc_calc(const uint8_t* data, uint32_t length, void* arg) {
+    NMBS_UNUSED_PARAM(arg);
     uint16_t crc = 0xFFFF;
     for (uint32_t i = 0; i < length; i++) {
         crc ^= (uint16_t) data[i];
@@ -270,7 +281,7 @@ static nmbs_error recv_msg_footer(nmbs_t* nmbs) {
     NMBS_DEBUG_PRINT("\n");
 
     if (nmbs->platform.transport == NMBS_TRANSPORT_RTU) {
-        uint16_t crc = nmbs_crc_calc(nmbs->msg.buf, nmbs->msg.buf_idx);
+        uint16_t crc = nmbs->platform.crc_calc(nmbs->msg.buf, nmbs->msg.buf_idx, nmbs->platform.arg);
 
         nmbs_error err = recv(nmbs, 2);
         if (err != NMBS_ERROR_NONE)
@@ -381,7 +392,7 @@ static nmbs_error send_msg(nmbs_t* nmbs) {
     NMBS_DEBUG_PRINT("\n");
 
     if (nmbs->platform.transport == NMBS_TRANSPORT_RTU) {
-        uint16_t crc = nmbs_crc_calc(nmbs->msg.buf, nmbs->msg.buf_idx);
+        uint16_t crc = nmbs->platform.crc_calc(nmbs->msg.buf, nmbs->msg.buf_idx, nmbs->platform.arg);
         put_2(nmbs, crc);
     }
 
@@ -1839,11 +1850,20 @@ static nmbs_error handle_req_fc(nmbs_t* nmbs) {
 }
 
 
+void nmbs_callbacks_create(nmbs_callbacks* callbacks) {
+    memset(callbacks, 0, sizeof(nmbs_callbacks));
+    callbacks->initialized = 0xFFFFDEBE;
+}
+
+
 nmbs_error nmbs_server_create(nmbs_t* nmbs, uint8_t address_rtu, const nmbs_platform_conf* platform_conf,
                               const nmbs_callbacks* callbacks) {
     if (platform_conf->transport == NMBS_TRANSPORT_RTU && address_rtu == 0)
         return NMBS_ERROR_INVALID_ARGUMENT;
 
+    if (!callbacks || callbacks->initialized != 0xFFFFDEBE)
+        return NMBS_ERROR_INVALID_ARGUMENT;
+
     nmbs_error ret = nmbs_create(nmbs, platform_conf);
     if (ret != NMBS_ERROR_NONE)
         return ret;

nanomodbus.h

@@ -139,6 +139,8 @@ typedef enum nmbs_transport {
  * A return value between `0` and `count - 1` will be treated as if a timeout occurred on the transport side. All other
  * values will be treated as transport errors.
  *
+ * Additionally, an optional crc_calc() function can be defined to override the default nanoMODBUS CRC calculation function.
+ *
  * These methods accept a pointer to arbitrary user-data, which is the arg member of this struct.
  * After the creation of an instance it can be changed with nmbs_set_platform_arg().
  */
@@ -148,7 +150,10 @@ typedef struct nmbs_platform_conf {
                     void* arg); /*!< Bytes read transport function pointer */
     int32_t (*write)(const uint8_t* buf, uint16_t count, int32_t byte_timeout_ms,
                      void* arg); /*!< Bytes write transport function pointer */
-    void* arg;                   /*!< User data, will be passed to functions above */
+    uint16_t (*crc_calc)(const uint8_t* data, uint32_t length,
+                         void* arg); /*!< CRC calculation function pointer. Optional */
+    void* arg;                       /*!< User data, will be passed to functions above */
+    uint32_t initialized; /*!< Reserved, workaround for older user code not calling nmbs_platform_conf_create() */
 } nmbs_platform_conf;
 
 
@@ -216,7 +221,8 @@ typedef struct nmbs_callbacks {
 #endif
 #endif
 
-    void* arg;    // User data, will be passed to functions above
+    void* arg;               // User data, will be passed to functions above
+    uint32_t initialized;    // Reserved, workaround for older user code not calling nmbs_callbacks_create()
 } nmbs_callbacks;
 
 
@@ -268,13 +274,23 @@ void nmbs_set_read_timeout(nmbs_t* nmbs, int32_t timeout_ms);
  */
 void nmbs_set_byte_timeout(nmbs_t* nmbs, int32_t timeout_ms);
 
+/** Create a new nmbs_platform_conf struct.
+ * @param platform_conf pointer to the nmbs_platform_conf instance
+ */
+void nmbs_platform_conf_create(nmbs_platform_conf* platform_conf);
+
 /** Set the pointer to user data argument passed to platform functions.
  * @param nmbs pointer to the nmbs_t instance
  * @param arg user data argument
  */
 void nmbs_set_platform_arg(nmbs_t* nmbs, void* arg);
 
 #ifndef NMBS_SERVER_DISABLED
+/** Create a new nmbs_callbacks struct.
+ * @param callbacks pointer to the nmbs_callbacks instance
+ */
+void nmbs_callbacks_create(nmbs_callbacks* callbacks);
+
 /** Create a new Modbus server.
  * @param nmbs pointer to the nmbs_t instance where the client will be created.
  * @param address_rtu RTU address of this server. Can be 0 if transport is not RTU.
@@ -510,7 +526,7 @@ nmbs_error nmbs_receive_raw_pdu_response(nmbs_t* nmbs, uint8_t* data_out, uint8_
  * @param data Data
  * @param length Length of the data
  */
-uint16_t nmbs_crc_calc(const uint8_t* data, uint32_t length);
+uint16_t nmbs_crc_calc(const uint8_t* data, uint32_t length, void* arg);
 
 #ifndef NMBS_STRERROR_DISABLED
 /** Convert a nmbs_error to string

tests/client_disabled.c

@@ -27,13 +27,15 @@ int main(int argc, char* argv[]) {
 
     nmbs_t nmbs;
 
-    nmbs_platform_conf platform_conf_empty = {
-            .transport = NMBS_TRANSPORT_TCP,
-            .read = read_empty,
-            .write = write_empty,
-    };
 
-    nmbs_callbacks callbacks_empty = {0};
+    nmbs_platform_conf platform_conf_empty;
+    nmbs_platform_conf_create(&platform_conf_empty);
+    platform_conf_empty.transport = NMBS_TRANSPORT_TCP;
+    platform_conf_empty.read = read_empty;
+    platform_conf_empty.write = write_empty;
+
+    nmbs_callbacks callbacks_empty;
+    nmbs_callbacks_create(&callbacks_empty);
 
     nmbs_error err = nmbs_server_create(&nmbs, 1, &platform_conf_empty, &callbacks_empty);
     if (err != 0)

tests/multi_server_rtu.c

@@ -122,7 +122,8 @@ int main(int argc, char* argv[]) {
     nmbs_set_read_timeout(&client, 5000);
     nmbs_set_byte_timeout(&client, 100);
 
-    nmbs_callbacks callbacks = {0};
+    nmbs_callbacks callbacks;
+    nmbs_callbacks_create(&callbacks);
     callbacks.read_coils = read_coils;
 
     err = nmbs_server_create(&server1, 33, &s1_conf, &callbacks);