Add ascii-art spectrum analyzer for SDR support

1 files changed, 247 insertions, 0 deletions

diff --git a/src/common/display_spectrum.c b/src/common/display_spectrum.c
new file mode 100644
index 0000000..fcdd706
--- /dev/null
+++ b/src/common/display_spectrum.c
@@ -0,0 +1,247 @@
+/* display spectrum of IQ data
+ *
+ * (C) 2016 by Andreas Eversberg <jolly@eversberg.eu>
+ * All Rights Reserved
+ *
+ * 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 3 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include "sample.h"
+#include "sender.h"
+#include "fft.h"
+
+#define HEIGHT	20
+
+static double buffer_max[MAX_DISPLAY_SPECTRUM];
+static char screen[HEIGHT][MAX_DISPLAY_WIDTH];
+static uint8_t screen_color[HEIGHT][MAX_DISPLAY_WIDTH];
+static int spectrum_on = 0;
+static double db = 100;
+
+static dispspectrum_t disp;
+
+void display_spectrum_init(int samplerate)
+{
+	memset(&disp, 0, sizeof(disp));
+	disp.interval_max = (double)samplerate * DISPLAY_INTERVAL + 0.5;
+	/* should not happen due to low interval */
+	if (disp.interval_max < MAX_DISPLAY_SPECTRUM - 1)
+		disp.interval_max = MAX_DISPLAY_SPECTRUM - 1;
+	memset(buffer_max, 0, sizeof(buffer_max));
+}
+
+void display_spectrum_on(int on)
+{
+	int j;
+	int w, h;
+
+	get_win_size(&w, &h);
+
+	if (spectrum_on) {
+		memset(&screen, ' ', sizeof(screen));
+		printf("\0337\033[H");
+		for (j = 0; j < HEIGHT; j++) {
+			screen[j][w] = '\0';
+			puts(screen[j]);
+		}
+		printf("\0338"); fflush(stdout);
+	}
+
+	if (on < 0) {
+		if (++spectrum_on == 2)
+			spectrum_on = 0;
+	} else
+		spectrum_on = on;
+}
+
+void display_spectrum_limit_scroll(int on)
+{
+	int w, h;
+
+	if (!spectrum_on)
+		return;
+
+	get_win_size(&w, &h);
+
+	printf("\0337");
+	printf("\033[%d;%dr", (on) ? HEIGHT + 1 : 1, h);
+	printf("\0338");
+}
+
+/*
+ * plot spectrum data:
+ *
+ */
+void display_spectrum(float *samples, int length)
+{
+	int width, h;
+	int pos, max;
+	double *buffer_I, *buffer_Q;
+	int color = 9; /* default color */
+	int i, j, k, count;
+	int m;
+	double I, Q, v, c;
+	int s, e;
+
+	if (!spectrum_on)
+		return;
+
+	get_win_size(&width, &h);
+	if (width > MAX_DISPLAY_SPECTRUM)
+		width = MAX_DISPLAY_SPECTRUM;
+
+	int heigh[width], low[width];
+
+	pos = disp.interval_pos;
+	max = disp.interval_max;
+	buffer_I = disp.buffer_I;
+	buffer_Q = disp.buffer_Q;
+
+	for (i = 0; i < length; i++) {
+		if (pos >= MAX_DISPLAY_SPECTRUM) {
+			if (++pos == max)
+				pos = 0;
+			continue;
+		}
+		buffer_I[pos] = samples[i * 2];
+		buffer_Q[pos] = samples[i * 2 + 1];
+		pos++;
+		if (pos == MAX_DISPLAY_SPECTRUM) {
+			/* calculate number of taps */
+			for (m = 0; m < 16; m++) {
+				if ((1 << m) == MAX_DISPLAY_SPECTRUM)
+					break;
+			}
+			if (m == 16) {
+				fprintf(stderr, "Size of spectrum is not a power of 2, please fix!\n");
+				abort();
+			}
+			fft_process(1, m, buffer_I, buffer_Q);
+			count = 0;
+			c = 0.0;
+			k = 0;
+			for (j = 0; j < MAX_DISPLAY_SPECTRUM; j++) {
+				/* scale result vertically */
+				I = buffer_I[(j + MAX_DISPLAY_SPECTRUM / 2) % MAX_DISPLAY_SPECTRUM];
+				Q = buffer_Q[(j + MAX_DISPLAY_SPECTRUM / 2) % MAX_DISPLAY_SPECTRUM];
+				v = sqrt(I*I + Q*Q);
+				v = log10(v) * 20 + db;
+				if (v < 0)
+					v = 0;
+				v /= db;
+				/* scale down result horizontally by combining values */
+				if (v > c)
+					c = v;
+				buffer_max[j] -= DISPLAY_INTERVAL / 10.0;
+				if (c > buffer_max[j])
+					buffer_max[j] = c;
+				count += width;
+				while (count >= MAX_DISPLAY_SPECTRUM) {
+					if (k >= width) {
+						fprintf(stderr, "Too many output values, please fix!\n");
+						abort();
+					}
+					/* heigh is the maximum value */
+					heigh[k] = (double)(HEIGHT * 2 - 1) * (1.0 - buffer_max[j]);
+					if (heigh[k] < 0)
+						heigh[k] = 0;
+					if (heigh[k] >= (HEIGHT * 2))
+						heigh[k] = (HEIGHT * 2) - 1;
+					/* low is the current value */
+					low[k] = (double)(HEIGHT * 2 - 1) * (1.0 - c);
+					if (low[k] < 0)
+						low[k] = 0;
+					if (low[k] >= (HEIGHT * 2))
+						low[k] = (HEIGHT * 2) - 1;
+					k++;
+					c = 0.0;
+					count -= MAX_DISPLAY_SPECTRUM;
+				}
+			}
+			if (k != width) {
+				fprintf(stderr, "k must be %d but is %d, please fix!\n", width, k);
+				abort();
+			}
+			/* plot scaled buffer */
+			memset(&screen, ' ', sizeof(screen));
+			memset(&screen_color, 7, sizeof(screen_color)); /* all white */
+			sprintf(screen[0], "(spectrum log %.0f dB", db);
+			*strchr(screen[0], '\0') = ')';
+			for (j = 0; j < width; j++) {
+				s = e = low[j];
+				if (j > 0 && low[j - 1] > e)
+					e = low[j - 1] - 1;
+				if (j < width - 1 && low[j + 1] > e)
+					e = low[j + 1] - 1;
+				if (s == e) {
+					if ((s & 1) == 0)
+						screen[s >> 1][j] = '\'';
+					else
+						screen[s >> 1][j] = '.';
+					screen_color[s >> 1][j] = 3;
+				} else {
+					if ((s & 1) == 0)
+						screen[s >> 1][j] = ':';
+					else
+						screen[s >> 1][j] = '.';
+					screen_color[s >> 1][j] = 3;
+					if ((e & 1) == 0)
+						screen[e >> 1][j] = '\'';
+					else
+						screen[e >> 1][j] = ':';
+					screen_color[e >> 1][j] = 3;
+					for (k = (s >> 1) + 1; k < (e >> 1); k++) {
+						screen[k][j] = ':';
+						screen_color[k][j] = 3;
+					}
+				}
+				s = heigh[j];
+				e = low[j];
+				if ((s >> 1) < (e >> 1)) {
+					if ((s & 1) == 0)
+						screen[s >> 1][j] = ':';
+					else
+						screen[s >> 1][j] = '.';
+					screen_color[s >> 1][j] = 4;
+					for (k = (s >> 1) + 1; k < (e >> 1); k++) {
+						screen[k][j] = ':';
+						screen_color[k][j] = 4;
+					}
+				}
+			}
+			printf("\0337\033[H");
+			for (j = 0; j < HEIGHT; j++) {
+				for (k = 0; k < width; k++) {
+					if (screen_color[j][k] != color) {
+						color = screen_color[j][k];
+						printf("\033[1;3%dm", color);
+					}
+					putchar(screen[j][k]);
+				}
+				printf("\n");
+			}
+			/* reset color and position */
+			printf("\033[0;39m\0338"); fflush(stdout);
+		}
+	}
+
+	disp.interval_pos = pos;
+}
+
+