Split X/26 packet handling into intermediate class

pagex26base holds methods for converting between the enhancements QList and teletext packets. A future page subclass for POP pages will re-use those same methods.
2020-12-26 15:34:23 +00:00
parent 035c2c5a31
commit aa25a27e17
5 changed files with 133 additions and 66 deletions
--- a/pagex26base.cpp
+++ b/pagex26base.cpp
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2020 Gavin MacGregor
+ *
+ * This file is part of QTeletextMaker.
+ *
+ * QTeletextMaker is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * QTeletextMaker 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with QTeletextMaker.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <QByteArray>
+
+#include "pagex26base.h"
+
+QByteArray PageX26Base::packetFromEnhancementList(int packetNumber) const
+{
+	QByteArray result(40, 0x00);
+
+	int enhanceListPointer;
+	X26Triplet lastTriplet;
+
+	for (int i=0; i<13; i++) {
+		enhanceListPointer = packetNumber*13+i;
+
+		if (enhanceListPointer < m_enhancements.size()) {
+			result[i*3+1] = m_enhancements.at(enhanceListPointer).address();
+			result[i*3+2] = m_enhancements.at(enhanceListPointer).mode() | ((m_enhancements.at(enhanceListPointer).data() & 1) << 5);
+			result[i*3+3] = m_enhancements.at(enhanceListPointer).data() >> 1;
+
+			// If this is the last triplet, get a copy to repeat to the end of the packet
+			if (enhanceListPointer == m_enhancements.size()-1) {
+				lastTriplet = m_enhancements.at(enhanceListPointer);
+				// If the last triplet was NOT a Termination Marker, make up one
+				if (lastTriplet.mode() != 0x1f || lastTriplet.address() != 0x3f) {
+					lastTriplet.setAddress(0x3f);
+					lastTriplet.setMode(0x1f);
+					lastTriplet.setData(0x07);
+				}
+			}
+		} else {
+			// We've gone past the end of the triplet list, so repeat the Termination Marker to the end
+			result[i*3+1] = lastTriplet.address();
+			result[i*3+2] = lastTriplet.mode() | ((lastTriplet.data() & 1) << 5);
+			result[i*3+3] = lastTriplet.data() >> 1;
+		}
+	}
+
+	return result;
+}
+
+void PageX26Base::setEnhancementListFromPacket(int packetNumber, QByteArray packetContents)
+{
+	// Preallocate entries in the m_enhancements list to hold our incoming triplets.
+	// We write "dummy" reserved 11110 Row Triplets in the allocated entries which then get overwritten by the packet contents.
+	// This is in case of missing packets so we can keep Local Object pointers valid.
+	while (m_enhancements.size() < (packetNumber+1)*13)
+		m_enhancements.append(m_paddingX26Triplet);
+
+	int enhanceListPointer;
+	X26Triplet newX26Triplet;
+
+	for (int i=0; i<13; i++) {
+		enhanceListPointer = packetNumber*13+i;
+
+		newX26Triplet.setAddress(packetContents.at(i*3+1) & 0x3f);
+		newX26Triplet.setMode(packetContents.at(i*3+2) & 0x1f);
+		newX26Triplet.setData(((packetContents.at(i*3+3) & 0x3f) << 1) | ((packetContents.at(i*3+2) & 0x20) >> 5));
+		m_enhancements[enhanceListPointer] = newX26Triplet;
+	}
+	if (newX26Triplet.mode() == 0x1f && newX26Triplet.address() == 0x3f && newX26Triplet.data() & 0x01)
+		// Last triplet was a Termination Marker (without ..follows) so clean up the repeated ones
+		while (m_enhancements.size()>1 && m_enhancements.at(m_enhancements.size()-2).mode() == 0x1f && m_enhancements.at(m_enhancements.size()-2).address() == 0x3f && m_enhancements.at(m_enhancements.size()-2).data() == newX26Triplet.data())
+			m_enhancements.removeLast();
+}