--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/oscilloscope.c	Wed Nov 23 09:36:42 2022 -0800
@@ -0,0 +1,130 @@
+#include "oscilloscope.h"
+#include "render.h"
+#include "blastem.h"
+
+#define INVALID_TRIGGER 0xFFFFFFFF
+#define WIDTH 1280
+#define HEIGHT 720
+
+static void scope_window_close(uint8_t which)
+{
+	if (current_system && current_system->toggle_debug_view) {
+		current_system->toggle_debug_view(current_system, DEBUG_OSCILLOSCOPE);
+	}
+}
+
+oscilloscope *create_oscilloscope()
+{
+	oscilloscope *scope = calloc(1, sizeof(oscilloscope));
+	scope->channel_storage = 4;
+	scope->channels = calloc(scope->channel_storage, sizeof(scope_channel));
+	scope->window = render_create_window("Oscilloscope", WIDTH, HEIGHT, scope_window_close);
+	return scope;
+}
+uint8_t scope_add_channel(oscilloscope *scope, const char *name, uint32_t sample_rate)
+{
+	if (scope->num_channels == scope->channel_storage) {
+		scope->channel_storage *= 2;
+		scope->channels = realloc(scope->channels, scope->channel_storage * sizeof(scope_channel));
+	}
+	uint8_t channel = scope->num_channels++;
+	scope_channel *chan = scope->channels + channel;
+	chan->name = name;
+	chan->period = sample_rate / 30;
+	chan->next_sample = 0;
+	chan->samples = calloc(chan->period, sizeof(int16_t));
+	chan->last_trigger = INVALID_TRIGGER;
+	chan->cur_trigger = INVALID_TRIGGER;
+	return channel;
+}
+void scope_add_sample(oscilloscope *scope, uint8_t channel, int16_t value, uint8_t trigger)
+{
+	if (channel >= scope->num_channels) {
+		return;
+	}
+	scope_channel *chan = scope->channels + channel;
+	if (trigger) {
+		chan->cur_trigger = chan->next_sample;
+	}
+	chan->samples[chan->next_sample++] = value;
+	if (chan->next_sample == chan->period) {
+		chan->next_sample = 0;
+	}
+}
+void scope_render(oscilloscope *scope)
+{
+	int pitch;
+	uint32_t *fb = render_get_framebuffer(scope->window, &pitch);
+	memset(fb, 0, HEIGHT * pitch);
+	pitch /= sizeof(uint32_t);
+	int offset = 0;
+	int column_width = WIDTH/3;
+	int width = column_width * 3;
+	int row_height = HEIGHT / ((scope->num_channels + 2) / 3);
+	float value_scale = (float)row_height / 20000.0f;
+	uint32_t *cur_line = fb;
+	for (uint8_t i = 0; i < scope->num_channels; i++)
+	{
+		float samples_per_pixel = (float)scope->channels[i].period / (float)(2*column_width);
+		uint32_t start = scope->channels[i].last_trigger;
+		if (start == INVALID_TRIGGER) {
+			if (scope->channels[i].next_sample >= scope->channels[i].period / 2) {
+				start = scope->channels[i].next_sample - scope->channels[i].period / 2;
+			} else {
+				start = scope->channels[i].period - (scope->channels[i].period /2 - scope->channels[i].next_sample);
+			}
+		}
+		scope->channels[i].last_trigger = scope->channels[i].cur_trigger;
+		scope->channels[i].cur_trigger = INVALID_TRIGGER;
+		float cur_sample = start;
+		int last_y = -1;
+		for (int x = offset; x < offset + column_width; x++)
+		{
+			//TODO: bresenham
+			//TODO: at least linear filtering
+			int16_t sample = scope->channels[i].samples[(int)(cur_sample + 0.5f)];
+			int y = (float)sample * value_scale + 0.5f;
+			if (y > row_height / 2) {
+				y = row_height / 2;
+			} else if (y < -(row_height / 2)) {
+				y = -(row_height / 2);
+			}
+			y += row_height / 2;
+			if (last_y >= 0) {
+				int delta = last_y > y ? -1 : 1;
+				while (last_y != y)
+				{
+					cur_line[last_y * pitch + x ] = 0xFFFFFFFF;
+					last_y += delta;
+				}
+			} else {
+				last_y = y;
+			}
+			cur_line[y * pitch + x ] = 0xFFFFFFFF;
+			cur_sample += samples_per_pixel;
+			if (cur_sample + 0.5f >= scope->channels[i].period) {
+				cur_sample -= scope->channels[i].period;
+			}
+		}
+	
+		offset += column_width;
+		if (offset >= width) {
+			offset = 0;
+			cur_line += pitch * row_height;
+		}
+	}
+	
+	
+	render_framebuffer_updated(scope->window, WIDTH);
+}
+
+void scope_close(oscilloscope *scope)
+{
+	render_destroy_window(scope->window);
+	for (uint8_t i = 0; i < scope->num_channels; i++)
+	{
+		free(scope->channels[i].samples);
+	}
+	free(scope->channels);
+	free(scope);
+}

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/oscilloscope.h	Wed Nov 23 09:36:42 2022 -0800
@@ -0,0 +1,27 @@
+#ifndef OSCILLOSCOPE_H_
+#define OSCILLOSCOPE_H_
+#include <stdint.h>
+
+typedef struct {
+	const char *name;
+	int16_t    *samples;
+	uint32_t   next_sample;
+	uint32_t   period;
+	uint32_t   last_trigger;
+	uint32_t   cur_trigger;
+} scope_channel;
+
+typedef struct {
+	scope_channel *channels;
+	uint8_t       num_channels;
+	uint8_t       channel_storage;
+	uint8_t       window;
+} oscilloscope;
+
+oscilloscope *create_oscilloscope();
+uint8_t scope_add_channel(oscilloscope *scope, const char *name, uint32_t sample_rate);
+void scope_add_sample(oscilloscope *scope, uint8_t channel, int16_t value, uint8_t trigger);
+void scope_render(oscilloscope *scope);
+void scope_close(oscilloscope *scope);
+
+#endif //OSCILLOSCOPE_H_
\ No newline at end of file