EDID parser library

Add a support library to parse EDID that will be used by platform
plugins.

In order to tell the screen manufacturer from the identifier, the
parsers reads /usr/share/hwdata/pnp.ids or, if it's missing, uses
a lookup table previously generated from that file with a Python script.

Change-Id: Ie021eb68be91f06dc0da54445f88e3533f78d23e
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

src/platformsupport/edid/edid.pro

@@ -0,0 +1,13 @@
+TARGET = QtEdidSupport
+MODULE = edid_support
+
+QT = core-private
+CONFIG += static internal_module
+
+DEFINES += QT_NO_CAST_FROM_ASCII
+PRECOMPILED_HEADER = ../../corelib/global/qt_pch.h
+
+HEADERS += qedidparser_p.h
+SOURCES += qedidparser.cpp
+
+load(qt_module)

src/platformsupport/edid/qedidparser.cpp

@@ -0,0 +1,177 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 Pier Luigi Fiorini <pierluigi.fiorini@gmail.com>
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include <QtCore/QFile>
+
+#include "qedidparser_p.h"
+#include "qedidvendortable_p.h"
+
+#define ARRAY_LENGTH(a) (sizeof (a) / sizeof (a)[0])
+
+#define EDID_DESCRIPTOR_ALPHANUMERIC_STRING 0xfe
+#define EDID_DESCRIPTOR_PRODUCT_NAME 0xfc
+#define EDID_DESCRIPTOR_SERIAL_NUMBER 0xff
+
+#define EDID_OFFSET_DATA_BLOCKS 0x36
+#define EDID_OFFSET_LAST_BLOCK 0x6c
+#define EDID_OFFSET_PNP_ID 0x08
+#define EDID_OFFSET_SERIAL 0x0c
+#define EDID_PHYSICAL_WIDTH 0x15
+#define EDID_OFFSET_PHYSICAL_HEIGHT 0x16
+
+QT_BEGIN_NAMESPACE
+
+QEdidParser::QEdidParser()
+{
+    // Cache vendors list from pnp.ids
+    const QString fileName = QLatin1String("/usr/share/hwdata/pnp.ids");
+    if (QFile::exists(fileName)) {
+        QFile file(fileName);
+
+        if (file.open(QFile::ReadOnly)) {
+            while (!file.atEnd()) {
+                QString line = QString::fromUtf8(file.readLine()).trimmed();
+
+                if (line.startsWith(QLatin1Char('#')))
+                    continue;
+
+                QStringList parts = line.split(QLatin1Char('\t'));
+                if (parts.count() > 1) {
+                    QString pnpId = parts.at(0);
+                    parts.removeFirst();
+                    m_vendorCache[pnpId] = parts.join(QLatin1Char(' '));
+                }
+            }
+
+            file.close();
+        }
+    }
+}
+
+bool QEdidParser::parse(const QByteArray &blob)
+{
+    const quint8 *data = reinterpret_cast<const quint8 *>(blob.constData());
+    const size_t length = blob.length();
+
+    // Verify header
+    if (length < 128)
+        return false;
+    if (data[0] != 0x00 || data[1] != 0xff)
+        return false;
+
+    /* Decode the PNP ID from three 5 bit words packed into 2 bytes
+     * /--08--\/--09--\
+     * 7654321076543210
+     * |\---/\---/\---/
+     * R  C1   C2   C3 */
+    char id[3];
+    id[0] = 'A' + ((data[EDID_OFFSET_PNP_ID] & 0x7c) / 4) - 1;
+    id[1] = 'A' + ((data[EDID_OFFSET_PNP_ID] & 0x3) * 8) + ((data[EDID_OFFSET_PNP_ID + 1] & 0xe0) / 32) - 1;
+    id[2] = 'A' + (data[EDID_OFFSET_PNP_ID + 1] & 0x1f) - 1;
+    identifier = QString::fromLatin1(id, 3);
+
+    // Clear manufacturer
+    manufacturer = QString();
+
+    // Serial number, will be overwritten by an ASCII descriptor
+    // when and if it will be found
+    quint32 serial = data[EDID_OFFSET_SERIAL]
+            + (data[EDID_OFFSET_SERIAL + 1] << 8)
+            + (data[EDID_OFFSET_SERIAL + 2] << 16)
+            + (data[EDID_OFFSET_SERIAL + 3] << 24);
+    if (serial > 0)
+        serialNumber = QString::number(serial);
+    else
+        serialNumber = QString();
+
+    // Parse EDID data
+    for (int i = 0; i < 5; ++i) {
+        const uint offset = EDID_OFFSET_DATA_BLOCKS + i * 18;
+
+        if (data[offset] != 0 || data[offset + 1] != 0 || data[offset + 2] != 0)
+            continue;
+
+        if (data[offset + 3] == EDID_DESCRIPTOR_PRODUCT_NAME)
+            model = parseEdidString(&data[offset + 5]);
+        else if (data[offset + 3] == EDID_DESCRIPTOR_ALPHANUMERIC_STRING)
+            identifier = parseEdidString(&data[offset + 5]);
+        else if (data[offset + 3] == EDID_DESCRIPTOR_SERIAL_NUMBER)
+            serialNumber = parseEdidString(&data[offset + 5]);
+    }
+
+    // Try to use cache first because it is potentially more updated
+    if (m_vendorCache.contains(identifier)) {
+        manufacturer = m_vendorCache[identifier];
+    } else {
+        // Find the manufacturer from the vendor lookup table
+        for (size_t i = 0; i < ARRAY_LENGTH(q_edidVendorTable); i++) {
+            if (strcmp(q_edidVendorTable[i].id, identifier.toLatin1().constData()) == 0) {
+                manufacturer = QString::fromUtf8(q_edidVendorTable[i].name);
+                break;
+            }
+        }
+    }
+
+    // If we don't know the manufacturer, fallback to PNP ID
+    if (manufacturer.isEmpty())
+        manufacturer = identifier;
+
+    // Physical size
+    physicalSize = QSizeF(data[EDID_PHYSICAL_WIDTH], data[EDID_OFFSET_PHYSICAL_HEIGHT]) * 10;
+
+    return true;
+}
+
+QString QEdidParser::parseEdidString(const quint8 *data)
+{
+    QByteArray buffer(reinterpret_cast<const char *>(data), 12);
+
+    // Erase carriage return and line feed
+    buffer = buffer.replace('\r', '\0').replace('\n', '\0');
+
+    // Replace non-printable characters with dash
+    for (int i = 0; i < buffer.count(); ++i) {
+        if (buffer[i] < '\040' && buffer[i] > '\176')
+            buffer[i] = '-';
+    }
+
+    return QString::fromLatin1(buffer.trimmed());
+}
+
+QT_END_NAMESPACE

src/platformsupport/edid/qedidparser_p.h

@@ -0,0 +1,78 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 Pier Luigi Fiorini <pierluigi.fiorini@gmail.com>
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the plugins of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QEDIDPARSER_P_H
+#define QEDIDPARSER_P_H
+
+#include <QtCore/QSize>
+#include <QtCore/QMap>
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+
+QT_BEGIN_NAMESPACE
+
+class QEdidParser
+{
+public:
+    QEdidParser();
+
+    bool parse(const QByteArray &blob);
+
+    QString identifier;
+    QString manufacturer;
+    QString model;
+    QString serialNumber;
+    QSizeF physicalSize;
+
+private:
+    QMap<QString, QString> m_vendorCache;
+
+    QString parseEdidString(const quint8 *data);
+};
+
+QT_END_NAMESPACE
+
+#endif // QEDIDPARSER_P_H