Started work on ADS-B TX baseband processor

firmware/baseband/proc_adsbtx.cpp

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2014 Jared Boone, ShareBrained Technology, Inc.
+ * Copyright (C) 2016 Furrtek
+ *
+ * This file is part of PortaPack.
+ *
+ * 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, 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; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "proc_adsbtx.hpp"
+#include "portapack_shared_memory.hpp"
+#include "sine_table_int8.hpp"
+#include "event_m4.hpp"
+
+#include <cstdint>
+
+void ADSBTXProcessor::execute(const buffer_c8_t& buffer) {
+	
+	// This is called at 2M/2048 = 977Hz
+	
+	if (!configured) return;
+	
+	for (size_t i = 0; i < buffer.count; i++) {
+		
+		// Synthesis at 2M
+		/*if (preamble == true) {
+			if (bit_pos >= 16) {
+				bit_pos = 0;
+				preamble = false;
+				bit_part = 0;
+			} else {
+				cur_bit = (preamble_parts << bit_pos) >> 15;
+				bit_pos++;
+			}
+		}*/
+		//if (preamble == false) {
+			if (!bit_part) {
+				if (bit_pos >= 112) {
+					// Stop
+					cur_bit = 0;
+				} else {
+					cur_bit = shared_memory.tx_data[bit_pos];
+					bit_pos++;
+					bit_part = 1;
+				}
+			} else {
+				bit_part = 0;
+				cur_bit ^= 1;
+			}
+		//}
+		
+		// 8D48: 10001101 01001000
+		//       1001010110100110 0110010110010101
+		
+		if (cur_bit) {
+			phase = (phase + 0x1FE0000);			// What ?
+			sphase = phase + (64 << 18);
+
+			re = (sine_table_i8[(sphase & 0x03FC0000) >> 18]);
+			im = (sine_table_i8[(phase & 0x03FC0000) >> 18]);
+		} else {
+			re = 0;
+			im = 0;
+		}
+	
+		buffer.p[i] = {(int8_t)re, (int8_t)im};
+	}
+	
+	// TEST
+	message.n = 200;
+	shared_memory.application_queue.push(message);
+	configured = false;
+}
+
+void ADSBTXProcessor::on_message(const Message* const p) {
+	const auto message = *reinterpret_cast<const ADSBConfigureMessage*>(p);
+	
+	if (message.id == Message::ID::ADSBConfigure) {
+		bit_pos = 0;
+		cur_bit = 0;
+		preamble = true;
+		configured = true;
+	}
+}
+
+int main() {
+	EventDispatcher event_dispatcher { std::make_unique<ADSBTXProcessor>() };
+	event_dispatcher.run();
+	return 0;
+}