From bd5f3be35d125845773e84c23500a4126e0d0f0d Mon Sep 17 00:00:00 2001
From: Hermann Detz <hermann.detz@gmail.com>
Date: Fri, 16 Oct 2020 09:20:02 +0200
Subject: [PATCH] Helper functions to convert modbus reg to float

---
 modbus/modbushelpers.cpp | 52 ++++++++++++++++++++++++++++++++++++++++
 modbus/modbushelpers.h   | 42 ++++++++++++++++++++++++++++++++
 2 files changed, 94 insertions(+)
 create mode 100644 modbus/modbushelpers.cpp
 create mode 100644 modbus/modbushelpers.h

diff --git a/modbus/modbushelpers.cpp b/modbus/modbushelpers.cpp
new file mode 100644
index 0000000..96b5394
--- /dev/null
+++ b/modbus/modbushelpers.cpp
@@ -0,0 +1,52 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+*
+* Copyright 2013 - 2020, nymea GmbH
+* Contact: contact@nymea.io
+*
+* This file is part of nymea.
+* This project including source code and documentation is protected by
+* copyright law, and remains the property of nymea GmbH. All rights, including
+* reproduction, publication, editing and translation, are reserved. The use of
+* this project is subject to the terms of a license agreement to be concluded
+* with nymea GmbH in accordance with the terms of use of nymea GmbH, available
+* under https://nymea.io/license
+*
+* GNU Lesser General Public License Usage
+* Alternatively, this project may be redistributed and/or modified under the
+* terms of the GNU Lesser General Public License as published by the Free
+* Software Foundation; version 3. This project is distributed in the hope that
+* it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+* Lesser General Public License for more details.
+*
+* You should have received a copy of the GNU Lesser General Public License
+* along with this project. If not, see <https://www.gnu.org/licenses/>.
+*
+* For any further details and any questions please contact us under
+* contact@nymea.io or see our FAQ/Licensing Information on
+* https://nymea.io/license/faq
+*
+* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#include "modbushelpers.h"
+
+#include <cstring>
+
+float ModbusHelpers::convertRegisterToFloat(const quint16 *reg) {
+    float result = 0.0;
+
+    if (reg != nullptr) {
+        /* low-order byte is sent first, so swap order */
+        quint32 tmp = 0.0;
+
+        tmp |= ((quint32)(reg[1]) << 16) & 0xFFFF0000;
+        tmp |= reg[0];
+
+        /* copy value over to float variable without any conversion */
+        /* needs to be done with char * to avoid pedantic compiler errors */
+        memcpy((char *)&result, (char *)&tmp, sizeof(result));
+    }
+
+    return result;
+}
+
diff --git a/modbus/modbushelpers.h b/modbus/modbushelpers.h
new file mode 100644
index 0000000..c9e7af2
--- /dev/null
+++ b/modbus/modbushelpers.h
@@ -0,0 +1,42 @@
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
+*
+* Copyright 2013 - 2020, nymea GmbH
+* Contact: contact@nymea.io
+*
+* This file is part of nymea.
+* This project including source code and documentation is protected by
+* copyright law, and remains the property of nymea GmbH. All rights, including
+* reproduction, publication, editing and translation, are reserved. The use of
+* this project is subject to the terms of a license agreement to be concluded
+* with nymea GmbH in accordance with the terms of use of nymea GmbH, available
+* under https://nymea.io/license
+*
+* GNU Lesser General Public License Usage
+* Alternatively, this project may be redistributed and/or modified under the
+* terms of the GNU Lesser General Public License as published by the Free
+* Software Foundation; version 3. This project is distributed in the hope that
+* it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+* Lesser General Public License for more details.
+*
+* You should have received a copy of the GNU Lesser General Public License
+* along with this project. If not, see <https://www.gnu.org/licenses/>.
+*
+* For any further details and any questions please contact us under
+* contact@nymea.io or see our FAQ/Licensing Information on
+* https://nymea.io/license/faq
+*
+* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+#ifndef MODBUSHELPERS_H
+#define MODBUSHELPERS_H
+
+#include <QtGlobal>
+
+class ModbusHelpers {
+public:
+    static float    convertRegisterToFloat(const quint16 *reg);
+};
+
+#endif
+