From da70a172565c06f34b94b13662d8a591ac3a4216 Mon Sep 17 00:00:00 2001
From: Peter M. Groen <pgroen@nuc64.osdev.nl>
Date: Mon, 2 Jan 2023 00:42:44 +0100
Subject: [PATCH] Added Request Class

---
 include/request.h | 102 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/modbustcp.cpp |   4 ++--
 2 files changed, 104 insertions(+), 2 deletions(-)
 create mode 100644 include/request.h

diff --git a/include/request.h b/include/request.h
new file mode 100644
index 0000000..e3597a3
--- /dev/null
+++ b/include/request.h
@@ -0,0 +1,102 @@
+/*
+ *  Copyright (c) 2023 Peter M. Groen
+ *
+ *  This source code is licensed under the MIT license found in the
+ *  LICENSE file in the root directory of this source tree.
+ */
+#pragma once
+
+#include <cstdint>
+#include <functional>
+#include <variant>
+#include <vector>
+
+/// The response based on the \ref Request made.
+struct Response
+{
+    /// Whether the \ref Request was successful.
+    /// Positive values indicate success and how many entries are in the \ref responseBuffer.
+    /// Negative values indicate failure and can be resolved with \ref Modbus::ErrorToString() to a string.
+    int resultValue = -1;
+
+    /// Buffer contaiining the response of the \ref Request.
+    std::vector<std::variant<uint8_t, uint16_t>> responseBuffer = {};
+};
+
+/// A request to be made over ModBus.
+///
+/// TThis contains all the information the stack needs to actually make the request.
+class Request
+{
+public:
+    /// Function code of the request.
+    /// We only support a small subset of the ModBus Standard.
+    enum class FunctionCode
+    {
+        READ_COILS,
+        READ_DISCRETE_INPUTS,
+        READ_HOLDING_REGISTERS,
+        READ_INPUT_REGISTERS,
+        WRITE_SINGLE_COIL,
+        WRITE_SINGLE_REGISTER,
+        WRITE_MULTIPLE_COILS,
+        WRITE_MULTIPLE_REGISTERS,
+        WRITE_FILE_RECORD,
+    };
+
+    /// Constructor taking all necessary information to create a request.
+    ///
+    /// @param  functionCode    - The code of the action this request wants to perform.
+    /// @param  slaveId         - The Device ID number.
+    /// @param  startAddress    - Register number to start reading from or writing to.
+    /// @param  numberOfItems   - Number of items to read or write from start_address.
+    /// @param  callback        - Function to call when this request returns a response.
+    Request(Request::FunctionCode functionCode,
+            int slaveId,
+            int startAddress,
+            int numberOfItems,
+            std::function<bool(Response)> callback)
+        : m_functionCode(functionCode)
+        , m_slaveId(slaveId)
+        , m_startAddress(startAddress)
+        , m_numberOfItems(numberOfItems)
+    {
+        callbacks.push_back(callback);
+    }
+
+    /// @return The functioncode this request handles.
+    FunctionCode GetFunctionCode() const {return m_functionCode;}
+
+    /// @return The slaveID of the device this request is intended for.
+    int GetSlaveId() const {return m_slaveId;}
+
+    /// @return The start Address of the register(s) we're reading.
+    int GetStartAddress() const {return m_startAddress;}
+
+    /// @return The number of registers we read from the \ref m_startAddress.
+    int GetNumberOfItems() const {return m_numberOfItems;}
+
+    /// @return The values read from, or to be written to, the device.
+    /// @note never change the length of this vector.
+    std::vector<int> GetDataBuffer() const {return m_dataBuffer;}
+
+    /// @return Callbacks registered to call when new data is available.
+    /// @note Functionn pointer returns False if the device state is OFFLINE. True, otherwise.
+    std::vector<std::function<bool(Response)>> callbacks;
+
+private:
+    /// Function code of this request.
+    FunctionCode    m_functionCode;
+
+    /// SlaveID of this request.
+    int             m_slaveId;
+
+    /// Start address of the register for this request
+    int             m_startAddress;
+
+    /// Amount of registers to read/write in this request
+    int             m_numberOfItems;
+
+    /// Data to send to the device; must be the same size as \ref m_numberOfItems.
+    std::vector<int>    m_dataBuffer;
+};
diff --git a/src/modbustcp.cpp b/src/modbustcp.cpp
index 7f95187..d07e3b6 100644
--- a/src/modbustcp.cpp
+++ b/src/modbustcp.cpp
@@ -9,8 +9,8 @@
 using namespace osdev::components::modbus;
 
 ModbusTcp::ModbusTcp(const ConnectionConfig &con_config)
-    : m_host( con_config.getIpAddress() )
-    , m_port( con_config.getPortNumber() )
+    : m_host(con_config.getIpAddress())
+    , m_port(con_config.getPortNumber())
 {
 
 }
--
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