Start building MicroPeak GUI tool

Download, save and analyze MicroPeak flight data

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 270 insertions, 0 deletions

diff --git a/micropeak/MicroData.java b/micropeak/MicroData.java
new file mode 100644
index 00000000..783ae40f
--- /dev/null
+++ b/micropeak/MicroData.java
@@ -0,0 +1,270 @@
+/*
+ * Copyright © 2012 Keith Packard <keithp@keithp.com>
+ *
+ * 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; version 2 of the License.
+ *
+ * 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.
+ */
+
+package org.altusmetrum.micropeak;
+
+import java.lang.*;
+import java.io.*;
+import java.util.*;
+import org.altusmetrum.AltosLib.*;
+
+public class MicroData {
+	public int		ground_pressure;
+	public int		min_pressure;
+	public int[]		pressures;
+	private double		time_step;
+	private double		ground_altitude;
+	private ArrayList<Integer>	bytes;
+	
+
+	class FileEndedException extends Exception {
+	}
+
+	class NonHexcharException extends Exception {
+	}
+
+	class InvalidCrcException extends Exception {
+	}
+
+	private int getc(InputStream f) throws IOException, FileEndedException {
+		int	c = f.read();
+
+		if (c == -1)
+			throw new FileEndedException();
+		bytes.add(c);
+		return c;
+	}
+
+	private int get_nonwhite(InputStream f) throws IOException, FileEndedException {
+		int	c;
+
+		for (;;) {
+			c = getc(f);
+			if (!Character.isWhitespace(c))
+				return c;
+		}
+	}
+
+	private int get_hexc(InputStream f) throws IOException, FileEndedException, NonHexcharException {
+		int	c = get_nonwhite(f);
+
+		if ('0' <= c && c <= '9')
+			return c - '0';
+		if ('a' <= c && c <= 'f')
+			return c - 'a' + 10;
+		if ('A' <= c && c <= 'F')
+			return c - 'A' + 10;
+		throw new NonHexcharException();
+	}
+
+	private static final int POLY = 0x8408;
+
+	private int log_crc(int crc, int b) {
+		int	i;
+
+		for (i = 0; i < 8; i++) {
+			if (((crc & 0x0001) ^ (b & 0x0001)) != 0)
+				crc = (crc >> 1) ^ POLY;
+			else
+				crc = crc >> 1;
+			b >>= 1;
+		}
+		return crc & 0xffff;
+	}
+
+	int	file_crc;
+
+	private int get_hex(InputStream f) throws IOException, FileEndedException, NonHexcharException {
+		int	a = get_hexc(f);
+		int	b = get_hexc(f);
+
+		int h = (a << 4) + b;
+
+		file_crc = log_crc(file_crc, h);
+		return h;
+	}
+
+	private boolean find_header(InputStream f) throws IOException {
+		try {
+			for (;;) {
+				if (get_nonwhite(f) == 'M' && get_nonwhite(f) == 'P')
+					return true;
+			}
+		} catch (FileEndedException fe) {
+			return false;
+		}
+	} 
+
+	private int get_32(InputStream f)  throws IOException, FileEndedException, NonHexcharException {
+		int	v = 0;
+		for (int i = 0; i < 4; i++) {
+			v += get_hex(f) << (i * 8);
+		}
+		return v;
+	}
+
+	private int get_16(InputStream f) throws IOException, FileEndedException, NonHexcharException {
+		int	v = 0;
+		for (int i = 0; i < 2; i++) {
+			v += get_hex(f) << (i * 8);
+		}
+		return v;
+	}
+
+	private int swap16(int i) {
+		return ((i << 8) & 0xff00) | ((i >> 8) & 0xff);
+	}
+
+	public boolean	crc_valid;
+
+	int mix_in (int high, int low) {
+		return  high - (high & 0xffff) + low;
+	}
+
+	boolean closer (int target, int a, int b) {
+		return Math.abs (target - a) < Math.abs(target - b);
+	}
+
+	public double altitude(int i) {
+		return AltosConvert.pressure_to_altitude(pressures[i]);
+	}
+
+	int fact(int n) {
+		if (n == 0)
+			return 1;
+		return n * fact(n-1);
+	}
+
+	int choose(int n, int k) {
+		return fact(n) / (fact(k) * fact(n-k));
+	}
+
+
+	public double avg_altitude(int center, int dist) {
+		int	start = center - dist;
+		int	stop = center + dist;
+
+		if (start < 0)
+			start = 0;
+		if (stop >= pressures.length)
+			stop = pressures.length - 1;
+
+		double	sum = 0;
+		double	div = 0;
+
+		int	n = dist * 2;
+
+		for (int i = start; i <= stop; i++) {
+			int	k = i - (center - dist);
+			int	c = choose (n, k);
+
+			sum += c * pressures[i];
+			div += c;
+		}
+
+		double pres = sum / div;
+
+		double alt = AltosConvert.pressure_to_altitude(pres);
+		return alt;
+	}
+
+	public double height(int i) {
+		return altitude(i) - ground_altitude;
+	}
+
+	static final int speed_avg = 3;
+	static final int accel_avg = 5;
+
+	private double avg_speed(int center, int dist) {
+		if (center == 0)
+			return 0;
+
+		double ai = avg_altitude(center, dist);
+		double aj = avg_altitude(center - 1, dist);
+		double s = (ai - aj) / time_step;
+
+		return s;
+	}
+
+	public double speed(int i) {
+		return avg_speed(i, speed_avg);
+	}
+
+	public double acceleration(int i) {
+		if (i == 0)
+			return 0;
+		return (avg_speed(i, accel_avg) - avg_speed(i-1, accel_avg)) / time_step;
+	}
+
+	public double time(int i) {
+		return i * time_step;
+	}
+
+	public void save (OutputStream f) throws IOException {
+		for (int c : bytes)
+			f.write(c);
+	}
+
+	public MicroData (InputStream f) throws IOException {
+		bytes = new ArrayList<Integer>();
+		if (!find_header(f))
+			throw new IOException();
+		try {
+			file_crc = 0xffff;
+			ground_pressure = get_32(f);
+			min_pressure = get_32(f);
+			int nsamples = get_16(f);
+			pressures = new int[nsamples + 1];
+
+			ground_altitude = AltosConvert.pressure_to_altitude(ground_pressure);
+			int cur = ground_pressure;
+			pressures[0] = cur;
+			for (int i = 0; i < nsamples; i++) {
+				int	k = get_16(f);
+				int	same = mix_in(cur, k);
+				int	up = mix_in(cur + 0x10000, k);
+				int	down = mix_in(cur - 0x10000, k);
+
+				if (closer (cur, same, up)) {
+					if (closer (cur, same, down))
+						cur = same;
+					else
+						cur = down;
+				} else {
+					if (closer (cur, up, down))
+						cur = up;
+					else
+						cur = down;
+				}
+				
+				pressures[i+1] = cur;
+			}
+
+			int current_crc = swap16(~file_crc & 0xffff);
+			int crc = get_16(f);
+
+			crc_valid = crc == current_crc;
+
+			time_step = 0.192;
+		} catch (FileEndedException fe) {
+			throw new IOException();
+		} catch (NonHexcharException ne) {
+			throw new IOException();
+		}
+	}
+	
+}