edge: Add GprsCodingScheme class

Currently the coding scheme is checked and compared at different
places which makes in cumbersome to extend it for EGPRS.

This class encapsules the coding scheme and provides required meta
information like sizes as well as helper methods.

Sponsored-by: On-Waves ehf

1 files changed, 129 insertions, 0 deletions

diff --git a/src/gprs_coding_scheme.h b/src/gprs_coding_scheme.h
new file mode 100644
index 00000000..71b64cf7
--- /dev/null
+++ b/src/gprs_coding_scheme.h
@@ -0,0 +1,129 @@
+/* gprs_coding_scheme.h
+ *
+ * Copyright (C) 2015 by Sysmocom s.f.m.c. GmbH
+ * Author: Jacob Erlbeck <jerlbeck@sysmocom.de>
+ *
+ * This program 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 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <stddef.h>
+
+
+class GprsCodingScheme {
+public:
+	enum Scheme {
+		UNKNOWN,
+		CS1, CS2, CS3, CS4,
+		MCS1, MCS2, MCS3, MCS4,
+		MCS5, MCS6, MCS7, MCS8, MCS9,
+		NUM_SCHEMES
+	};
+
+	enum Mode {
+		GPRS,
+		EGPRS_GMSK,
+		EGPRS,
+	};
+
+	GprsCodingScheme(Scheme s = UNKNOWN);
+
+	operator bool() const {return m_scheme != UNKNOWN;}
+	operator int()  const {return (int)m_scheme;}
+	void operator =(Scheme s);
+	void operator =(GprsCodingScheme o);
+	bool isValid()   const {return UNKNOWN <= m_scheme && m_scheme <= MCS9;}
+	bool isGprs()   const {return CS1 <= m_scheme && m_scheme <= CS4;}
+	bool isEgprs()  const {return m_scheme >= MCS1;}
+	bool isEgprsGmsk()  const {return isEgprs() && m_scheme <= MCS4;}
+	bool isCompatible(Mode mode) const;
+
+	void inc(Mode mode);
+	void dec(Mode mode);
+
+	unsigned int sizeUL() const;
+	unsigned int sizeDL() const;
+	unsigned int maxBytesUL() const;
+	unsigned int maxBytesDL() const;
+	unsigned int spareBitsUL() const;
+	unsigned int spareBitsDL() const;
+	const char *name() const;
+
+	static GprsCodingScheme getBySizeUL(unsigned size);
+
+private:
+	enum Scheme m_scheme;
+};
+
+inline bool GprsCodingScheme::isCompatible(Mode mode) const
+{
+	switch (mode) {
+	case GPRS: return isGprs();
+	case EGPRS_GMSK: return isEgprsGmsk();
+	case EGPRS: return isEgprs();
+	}
+
+	return false;
+}
+
+inline void GprsCodingScheme::inc(Mode mode)
+{
+	if (!isCompatible(mode))
+		/* This should not happen. TODO: Use assert? */
+		return;
+
+	Scheme new_cs(Scheme(m_scheme + 1));
+	if (!GprsCodingScheme(new_cs).isCompatible(mode))
+		/* Clipping, do not change the value */
+		return;
+
+	m_scheme = new_cs;
+}
+
+inline void GprsCodingScheme::dec(Mode mode)
+{
+	if (!isCompatible(mode))
+		/* This should not happen. TODO: Use assert? */
+		return;
+
+	Scheme new_cs(Scheme(m_scheme - 1));
+	if (!GprsCodingScheme(new_cs).isCompatible(mode))
+		/* Clipping, do not change the value */
+		return;
+
+	m_scheme = new_cs;
+}
+
+inline GprsCodingScheme::GprsCodingScheme(Scheme s)
+	: m_scheme(s)
+{
+	if (!isValid())
+		m_scheme = UNKNOWN;
+}
+
+inline void GprsCodingScheme::operator =(Scheme s)
+{
+	m_scheme = s;
+
+	if (!isValid())
+		m_scheme = UNKNOWN;
+}
+
+inline void GprsCodingScheme::operator =(GprsCodingScheme o)
+{
+	m_scheme = o.m_scheme;
+}