commit 058bc70b84fa40b0318a43d1e660e3ea616c6067
Author: Thies Lennart Alff <lennart.alff@gmail.com>
Date:   Thu Feb 20 17:13:51 2025 +0100

    initial commit

diff --git a/include/hydrolink/hydrolink.h b/include/hydrolink/hydrolink.h
new file mode 100644
index 0000000..645f402
--- /dev/null
+++ b/include/hydrolink/hydrolink.h
@@ -0,0 +1,7 @@
+#pragma once
+#include "protocol.h"
+#include "hydrolink_msg_ack.h"
+#include "hydrolink_msg_set_cmd.h"
+#include "hydrolink_msg_set_response.h"
+#include "hydrolink_msg_get_cmd.h"
+#include "hydrolink_msg_get_response.h"
diff --git a/include/hydrolink/hydrolink_enums.h b/include/hydrolink/hydrolink_enums.h
new file mode 100644
index 0000000..ba5258f
--- /dev/null
+++ b/include/hydrolink/hydrolink_enums.h
@@ -0,0 +1,20 @@
+#pragma once
+typedef enum CMD_ID {
+CMD_ID_SWITCH = 1, /// Command for getting/setting the state of a switch
+CMD_ID_CMD_ID_PWM = 2, /// Command for getting/setting the value of a PWM channel
+CMD_ID_ENUM_END = 3
+}CMD_ID;
+                    #pragma once
+typedef enum CMD_RESULT {
+CMD_RESULT_SUCCESS = 1, /// 
+CMD_RESULT_FAILED = 2, /// 
+CMD_RESULT_CMD_UKNOWN = 3, /// The received command was unknown or unhandled.
+CMD_RESULT_ENUM_END = 4
+}CMD_RESULT;
+                    #pragma once
+typedef enum ACK {
+ACK_ACK = 1, /// 
+ACK_NACK = 2, /// 
+ACK_ENUM_END = 3
+}ACK;
+                    
\ No newline at end of file
diff --git a/include/hydrolink/hydrolink_msg_ack.h b/include/hydrolink/hydrolink_msg_ack.h
new file mode 100644
index 0000000..087d806
--- /dev/null
+++ b/include/hydrolink/hydrolink_msg_ack.h
@@ -0,0 +1,25 @@
+#pragma once
+#include "protocol.h"
+#define HYDROLINK_MSG_ID_ACK 1
+#define HYDROLINK_MSG_ID_ACK_LEN 1
+#define HYDROLINK_MSG_ID_1_LEN 1
+#define HYDROLINK_MSG_ID_ACK_CRC_EXTRA 73
+
+typedef struct hydrolink_msg_ack_t_s {
+uint8_t ack; ///  
+} hydrolink_msg_ack_t;
+
+void hydrolink_ack_msg_encode(uint8_t src_id, uint8_t dst_id, const hydrolink_msg_ack_t *msg, hydrolink_msg_t *packet) {
+  packet->id = HYDROLINK_MSG_ID_ACK;
+  packet->src_id = src_id;
+  packet->dst_id = dst_id;
+  packet->length = HYDROLINK_MSG_ID_1_LEN + HYDROLINK_NON_PAYLOAD_LEN;
+  hydrolink_put_uint8_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 0, msg->ack); 
+}
+                
+static inline uint8_t hydrolink_msg_ack_get_ack(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_uint8_t(packet, 0);
+}
+static inline void hydrolink_msgack_decode(const hydrolink_msg_t *packet, hydrolink_msg_ack_t *ack) {
+  ack->ack = hydrolink_msg_ack_get_ack(packet);
+}
\ No newline at end of file
diff --git a/include/hydrolink/hydrolink_msg_get_cmd.h b/include/hydrolink/hydrolink_msg_get_cmd.h
new file mode 100644
index 0000000..84334f6
--- /dev/null
+++ b/include/hydrolink/hydrolink_msg_get_cmd.h
@@ -0,0 +1,31 @@
+#pragma once
+#include "protocol.h"
+#define HYDROLINK_MSG_ID_GET_CMD 4
+#define HYDROLINK_MSG_ID_GET_CMD_LEN 2
+#define HYDROLINK_MSG_ID_4_LEN 2
+#define HYDROLINK_MSG_ID_GET_CMD_CRC_EXTRA 38
+
+typedef struct hydrolink_msg_get_cmd_t_s {
+uint8_t index; ///  
+uint8_t cmd_id; ///  
+} hydrolink_msg_get_cmd_t;
+
+void hydrolink_get_cmd_msg_encode(uint8_t src_id, uint8_t dst_id, const hydrolink_msg_get_cmd_t *msg, hydrolink_msg_t *packet) {
+  packet->id = HYDROLINK_MSG_ID_GET_CMD;
+  packet->src_id = src_id;
+  packet->dst_id = dst_id;
+  packet->length = HYDROLINK_MSG_ID_4_LEN + HYDROLINK_NON_PAYLOAD_LEN;
+  hydrolink_put_uint8_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 0, msg->index);
+  hydrolink_put_uint8_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 1, msg->cmd_id); 
+}
+                
+static inline uint8_t hydrolink_msg_get_cmd_get_index(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_uint8_t(packet, 0);
+}
+static inline uint8_t hydrolink_msg_get_cmd_get_cmd_id(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_uint8_t(packet, 1);
+}
+static inline void hydrolink_msgget_cmd_decode(const hydrolink_msg_t *packet, hydrolink_msg_get_cmd_t *get_cmd) {
+  get_cmd->index = hydrolink_msg_get_cmd_get_index(packet);
+  get_cmd->cmd_id = hydrolink_msg_get_cmd_get_cmd_id(packet);
+}
\ No newline at end of file
diff --git a/include/hydrolink/hydrolink_msg_get_response.h b/include/hydrolink/hydrolink_msg_get_response.h
new file mode 100644
index 0000000..5ee68fe
--- /dev/null
+++ b/include/hydrolink/hydrolink_msg_get_response.h
@@ -0,0 +1,37 @@
+#pragma once
+#include "protocol.h"
+#define HYDROLINK_MSG_ID_GET_RESPONSE 3
+#define HYDROLINK_MSG_ID_GET_RESPONSE_LEN 6
+#define HYDROLINK_MSG_ID_3_LEN 6
+#define HYDROLINK_MSG_ID_GET_RESPONSE_CRC_EXTRA 28
+
+typedef struct hydrolink_msg_get_response_t_s {
+int32_t value; ///  
+uint8_t result; ///  
+uint8_t cmd_id; ///  
+} hydrolink_msg_get_response_t;
+
+void hydrolink_get_response_msg_encode(uint8_t src_id, uint8_t dst_id, const hydrolink_msg_get_response_t *msg, hydrolink_msg_t *packet) {
+  packet->id = HYDROLINK_MSG_ID_GET_RESPONSE;
+  packet->src_id = src_id;
+  packet->dst_id = dst_id;
+  packet->length = HYDROLINK_MSG_ID_3_LEN + HYDROLINK_NON_PAYLOAD_LEN;
+  hydrolink_put_int32_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 0, msg->value);
+  hydrolink_put_uint8_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 4, msg->result);
+  hydrolink_put_uint8_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 5, msg->cmd_id); 
+}
+                
+static inline int32_t hydrolink_msg_get_response_get_value(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_int32_t(packet, 0);
+}
+static inline uint8_t hydrolink_msg_get_response_get_result(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_uint8_t(packet, 4);
+}
+static inline uint8_t hydrolink_msg_get_response_get_cmd_id(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_uint8_t(packet, 5);
+}
+static inline void hydrolink_msgget_response_decode(const hydrolink_msg_t *packet, hydrolink_msg_get_response_t *get_response) {
+  get_response->value = hydrolink_msg_get_response_get_value(packet);
+  get_response->result = hydrolink_msg_get_response_get_result(packet);
+  get_response->cmd_id = hydrolink_msg_get_response_get_cmd_id(packet);
+}
\ No newline at end of file
diff --git a/include/hydrolink/hydrolink_msg_set_cmd.h b/include/hydrolink/hydrolink_msg_set_cmd.h
new file mode 100644
index 0000000..753e912
--- /dev/null
+++ b/include/hydrolink/hydrolink_msg_set_cmd.h
@@ -0,0 +1,37 @@
+#pragma once
+#include "protocol.h"
+#define HYDROLINK_MSG_ID_SET_CMD 2
+#define HYDROLINK_MSG_ID_SET_CMD_LEN 6
+#define HYDROLINK_MSG_ID_2_LEN 6
+#define HYDROLINK_MSG_ID_SET_CMD_CRC_EXTRA 58
+
+typedef struct hydrolink_msg_set_cmd_t_s {
+int32_t value; ///  
+uint8_t index; ///  
+uint8_t cmd_id; ///  Command defined as in CMD_ID enum.
+} hydrolink_msg_set_cmd_t;
+
+void hydrolink_set_cmd_msg_encode(uint8_t src_id, uint8_t dst_id, const hydrolink_msg_set_cmd_t *msg, hydrolink_msg_t *packet) {
+  packet->id = HYDROLINK_MSG_ID_SET_CMD;
+  packet->src_id = src_id;
+  packet->dst_id = dst_id;
+  packet->length = HYDROLINK_MSG_ID_2_LEN + HYDROLINK_NON_PAYLOAD_LEN;
+  hydrolink_put_int32_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 0, msg->value);
+  hydrolink_put_uint8_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 4, msg->index);
+  hydrolink_put_uint8_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 5, msg->cmd_id); 
+}
+                
+static inline int32_t hydrolink_msg_set_cmd_get_value(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_int32_t(packet, 0);
+}
+static inline uint8_t hydrolink_msg_set_cmd_get_index(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_uint8_t(packet, 4);
+}
+static inline uint8_t hydrolink_msg_set_cmd_get_cmd_id(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_uint8_t(packet, 5);
+}
+static inline void hydrolink_msgset_cmd_decode(const hydrolink_msg_t *packet, hydrolink_msg_set_cmd_t *set_cmd) {
+  set_cmd->value = hydrolink_msg_set_cmd_get_value(packet);
+  set_cmd->index = hydrolink_msg_set_cmd_get_index(packet);
+  set_cmd->cmd_id = hydrolink_msg_set_cmd_get_cmd_id(packet);
+}
\ No newline at end of file
diff --git a/include/hydrolink/hydrolink_msg_set_response.h b/include/hydrolink/hydrolink_msg_set_response.h
new file mode 100644
index 0000000..935edaf
--- /dev/null
+++ b/include/hydrolink/hydrolink_msg_set_response.h
@@ -0,0 +1,31 @@
+#pragma once
+#include "protocol.h"
+#define HYDROLINK_MSG_ID_SET_RESPONSE 3
+#define HYDROLINK_MSG_ID_SET_RESPONSE_LEN 2
+#define HYDROLINK_MSG_ID_3_LEN 2
+#define HYDROLINK_MSG_ID_SET_RESPONSE_CRC_EXTRA 250
+
+typedef struct hydrolink_msg_set_response_t_s {
+uint8_t result; ///  
+uint8_t cmd_id; ///  
+} hydrolink_msg_set_response_t;
+
+void hydrolink_set_response_msg_encode(uint8_t src_id, uint8_t dst_id, const hydrolink_msg_set_response_t *msg, hydrolink_msg_t *packet) {
+  packet->id = HYDROLINK_MSG_ID_SET_RESPONSE;
+  packet->src_id = src_id;
+  packet->dst_id = dst_id;
+  packet->length = HYDROLINK_MSG_ID_3_LEN + HYDROLINK_NON_PAYLOAD_LEN;
+  hydrolink_put_uint8_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 0, msg->result);
+  hydrolink_put_uint8_t(HYDROLINK_PAYLOAD_NON_CONST(packet), 1, msg->cmd_id); 
+}
+                
+static inline uint8_t hydrolink_msg_set_response_get_result(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_uint8_t(packet, 0);
+}
+static inline uint8_t hydrolink_msg_set_response_get_cmd_id(const hydrolink_msg_t *packet) {
+  return HYDROLINK_RETURN_uint8_t(packet, 1);
+}
+static inline void hydrolink_msgset_response_decode(const hydrolink_msg_t *packet, hydrolink_msg_set_response_t *set_response) {
+  set_response->result = hydrolink_msg_set_response_get_result(packet);
+  set_response->cmd_id = hydrolink_msg_set_response_get_cmd_id(packet);
+}
\ No newline at end of file
diff --git a/include/hydrolink/protocol.h b/include/hydrolink/protocol.h
new file mode 100644
index 0000000..3d54cf0
--- /dev/null
+++ b/include/hydrolink/protocol.h
@@ -0,0 +1,155 @@
+
+#pragma once
+
+#include <stdint.h>
+#define HYDROLINK_HEADER_LEN 4
+#define HYDROLINK_CRC_LEN 2
+#define HYDROLINK_NON_PAYLOAD_LEN (HYDROLINK_HEADER_LEN + HYDROLINK_CRC_LEN)
+#define HYDROLINK_MAX_PAYLOAD_LEN 6
+#define HYDROLINK_MAX_MSG_LEN (HYDROLINK_MAX_PAYLOAD_LEN + HYDROLINK_NON_PAYLOAD_LEN)
+
+struct hydrolink_msg_s;
+
+typedef struct hydrolink_msg_s hydrolink_msg_t;
+
+struct hydrolink_msg_s {
+  uint8_t id;
+  uint8_t payload_length;
+  uint8_t dst_id;
+  uint8_t src_id;
+  uint8_t payload[HYDROLINK_MAX_PAYLOAD_LEN];
+  uint16_t crc;
+};
+
+#define HYDROLINK_PAYLOAD(msg) ((const char *)(&((msg)->payload[0])))
+#define HYDROLINK_PAYLOAD_NON_CONST(msg) ((char *)(&((msg)->payload[0])))
+
+#define hydrolink_put_float(buf, wire_offset, b) byte_swap_4(&buf[wire_offset], (const char *)&b)
+#define hydrolink_put_double(buf, wire_offset, b) byte_swap_8(&buf[wire_offset], (const char *)&b)
+#define hydrolink_put_char(buf, wire_offset, b) buf[wire_offset] = (char)b
+#define hydrolink_put_int8_t(buf, wire_offset, b) buf[wire_offset] = (int8_t)b
+#define hydrolink_put_uint8_t(buf, wire_offset, b) buf[wire_offset] = (uint8_t)b
+#define hydrolink_put_int16_t(buf, wire_offset, b) byte_swap_2(&buf[wire_offset], (const char *)&b)
+#define hydrolink_put_uint16_t(buf, wire_offset, b) byte_swap_2(&buf[wire_offset], (const char *)&b)
+#define hydrolink_put_int32_t(buf, wire_offset, b) byte_swap_4(&buf[wire_offset], (const char *)&b)
+#define hydrolink_put_uint32_t(buf, wire_offset, b) byte_swap_4(&buf[wire_offset], (const char *)&b)
+#define hydrolink_put_int64_t(buf, wire_offset, b) byte_swap_8(&buf[wire_offset], (const char *)&b)
+#define hydrolink_put_uint64_t(buf, wire_offset, b) byte_swap_8(&buf[wire_offset], (const char *)&b)
+
+inline void byte_swap_2(char *dst, const char *src) {
+  dst[0] = src[1];
+  dst[1] = src[0];
+}
+
+inline void byte_swap_4(char *dst, const char *src) {
+  dst[0] = src[3];
+  dst[1] = src[2];
+  dst[2] = src[1];
+  dst[3] = src[0];
+}
+
+inline void byte_swap_8(char *dst, const char *src) {
+  dst[0] = src[7];
+  dst[1] = src[6];
+  dst[2] = src[5];
+  dst[3] = src[4];
+  dst[4] = src[3];
+  dst[5] = src[2];
+  dst[6] = src[1];
+  dst[7] = src[0];
+}
+                
+#define HYDROLINK_MSG_RETURN_TYPE(TYPE, SIZE) \
+static inline TYPE HYDROLINK_RETURN_## TYPE(const hydrolink_msg_t *msg, uint8_t offset) {\
+  TYPE ret;  \
+  byte_swap_## SIZE((char*)&ret, &HYDROLINK_PAYLOAD(msg)[offset]); \
+  return ret; \
+}
+                
+HYDROLINK_MSG_RETURN_TYPE(float, 4)
+
+HYDROLINK_MSG_RETURN_TYPE(double, 8)
+
+#define HYDROLINK_RETURN_char(msg, wire_offset) (char)HYDROLINK_PAYLOAD(msg)[wire_offset]
+#define HYDROLINK_RETURN_int8_t(msg, wire_offset) (int8_t)HYDROLINK_PAYLOAD(msg)[wire_offset]
+#define HYDROLINK_RETURN_uint8_t(msg, wire_offset) (uint8_t)HYDROLINK_PAYLOAD(msg)[wire_offset]
+HYDROLINK_MSG_RETURN_TYPE(int16_t, 2)
+
+HYDROLINK_MSG_RETURN_TYPE(uint16_t, 2)
+
+HYDROLINK_MSG_RETURN_TYPE(int32_t, 4)
+
+HYDROLINK_MSG_RETURN_TYPE(uint32_t, 4)
+
+HYDROLINK_MSG_RETURN_TYPE(int64_t, 8)
+
+HYDROLINK_MSG_RETURN_TYPE(uint64_t, 8)
+
+inline void crc_xmodem_init(uint16_t *crc) { *crc = 0; }
+
+inline void crc_xmodem_accumulate(uint8_t data, uint16_t *crc) {
+  *crc = *crc ^ ((uint16_t)data << 8);
+  for (uint8_t j = 0; j < 8; j++) {
+    if (*crc & 0x8000) {
+      *crc = (*crc << 1) ^ 0x1021;
+    } else {
+      *crc <<= 1;
+    }
+  }
+}
+
+inline uint16_t crc_xmodem_calculate(const uint8_t *data, uint8_t length) {
+  uint16_t crc;
+  crc_xmodem_init(&crc);
+  for (uint8_t i = 0; i < length; i++) {
+    crc_xmodem_accumulate(*data, &crc);
+  }
+  return crc;
+}
+
+void hydrolink_fill_header_and_crc(hydrolink_msg_t *msg, uint8_t msg_id, uint8_t payload_length, uint8_t dst_id, uint8_t src_id, uint8_t crc_extra) {
+  msg->id = msg_id;
+  msg->payload_length = payload_length;
+  msg->dst_id = dst_id;
+  msg->src_id = src_id;
+  uint16_t crc;
+  crc_xmodem_init(&crc);
+  for(int i = 0; i < msg->payload_length; ++i) {
+    crc_xmodem_accumulate(msg->payload[i], &crc);
+  }
+  crc_xmodem_accumulate(crc_extra, &crc);
+  msg->crc = crc;
+}
+
+uint8_t hydrolink_serialize_message(hydrolink_msg_t *msg, uint8_t *buffer) {
+  buffer[0] = msg->id;
+  buffer[1] = msg->payload_length;
+  buffer[2] = msg->dst_id;
+  buffer[3] = msg->src_id;
+  uint8_t *p = &buffer[4];
+  for(int i =0; i<msg->payload_length;++i) {
+    *p++ = msg->payload[i]; 
+  }
+  *p++ = (uint8_t)(msg->crc >> 8);
+  *p++ = (uint8_t)(msg->crc & 0xff);
+  return HYDROLINK_NON_PAYLOAD_LEN + msg->payload_length;
+}
+
+uint8_t hydrolink_deserialize_header(hydrolink_msg_t *msg, uint8_t *buffer, uint8_t buffer_length) {
+  if (buffer_length < HYDROLINK_NON_PAYLOAD_LEN) {
+    return 0;
+  }
+  msg->id = buffer[0];
+  msg->payload_length = buffer[1];
+  msg->dst_id = buffer[2];
+  msg->src_id = buffer[3];
+  msg->crc = buffer[buffer_length-1] | (((uint16_t)buffer[buffer_length-2]) << 8);
+  if (msg->payload_length + HYDROLINK_NON_PAYLOAD_LEN != buffer_length) {
+    return 0;
+  }
+  uint8_t *p = &buffer[HYDROLINK_HEADER_LEN];
+  for (int i = 0; i < msg->payload_length; ++i) {
+    msg->payload[i] = *p++;
+  }
+  return msg->payload_length + HYDROLINK_NON_PAYLOAD_LEN;
+}