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, 104 insertions, 0 deletions

diff --git a/src/gprs_coding_scheme.cpp b/src/gprs_coding_scheme.cpp
new file mode 100644
index 00000000..3488b320
--- /dev/null
+++ b/src/gprs_coding_scheme.cpp
@@ -0,0 +1,104 @@
+/* gprs_coding_scheme.cpp
+ *
+ * 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.
+ */
+
+
+#include "gprs_coding_scheme.h"
+
+static struct {
+	struct {
+		unsigned bytes;
+		unsigned ext_bits;
+	} uplink, downlink;
+	const char *name;
+} mcs_info[GprsCodingScheme::NUM_SCHEMES] = {
+	{{0, 0},    {0, 0},   "UNKNOWN"},
+	{{23, 0},   {23, 0},  "CS-1"},
+	{{33, 7},   {33, 7},  "CS-2"},
+	{{39, 3},   {39, 3},  "CS-3"},
+	{{53, 7},   {53, 7},  "CS-4"},
+
+	{{26, 1},   {26, 1},  "MCS-1"},
+	{{32, 1},   {32, 1},  "MCS-2"},
+	{{41, 1},   {41, 1},  "MCS-3"},
+	{{48, 1},   {48, 1},  "MCS-4"},
+
+	{{60, 7},   {59, 6},  "MCS-5"},
+	{{78, 7},   {77, 6},  "MCS-6"},
+	{{118, 2},  {117, 4}, "MCS-7"},
+	{{142, 2},  {141, 4}, "MCS-8"},
+	{{154, 2},  {153, 4}, "MCS-9"},
+};
+
+
+GprsCodingScheme GprsCodingScheme::getBySizeUL(unsigned size)
+{
+	switch (size) {
+		case 23: return GprsCodingScheme(CS1);
+		case 27: return GprsCodingScheme(MCS1);
+		case 33: return GprsCodingScheme(MCS2);
+		case 34: return GprsCodingScheme(CS2);
+		case 40: return GprsCodingScheme(CS3);
+		case 42: return GprsCodingScheme(MCS3);
+		case 49: return GprsCodingScheme(MCS4);
+		case 54: return GprsCodingScheme(CS4);
+		case 61: return GprsCodingScheme(MCS5);
+		case 79: return GprsCodingScheme(MCS6);
+		case 119: return GprsCodingScheme(MCS7);
+		case 143: return GprsCodingScheme(MCS8);
+		case 155: return GprsCodingScheme(MCS9);
+	}
+
+	return GprsCodingScheme(UNKNOWN);
+}
+
+unsigned int GprsCodingScheme::sizeUL() const
+{
+	return maxBytesUL() + (spareBitsUL() ? 1 : 0);
+}
+
+unsigned int GprsCodingScheme::maxBytesUL() const
+{
+	return mcs_info[m_scheme].uplink.bytes;
+}
+
+unsigned int GprsCodingScheme::spareBitsUL() const
+{
+	return mcs_info[m_scheme].uplink.ext_bits;
+}
+
+unsigned int GprsCodingScheme::sizeDL() const
+{
+	return maxBytesDL() + (spareBitsDL() ? 1 : 0);
+}
+
+unsigned int GprsCodingScheme::maxBytesDL() const
+{
+	return mcs_info[m_scheme].downlink.bytes;
+}
+
+unsigned int GprsCodingScheme::spareBitsDL() const
+{
+	return mcs_info[m_scheme].downlink.ext_bits;
+}
+
+const char *GprsCodingScheme::name() const
+{
+	return mcs_info[m_scheme].name;
+}