os-workshop

commit 03be9654a197738bdd3d390235d4f75f44a1a41a
parent 5114163ca82270239d131ba66f6d3cd07f6ba356
Author: Brian Swetland <swetland@frotz.net>
Date:   Sat,  7 May 2022 10:22:06 -0700

mandelbrot-fb: graphical mandelbrot program

Diffstat:
A
misc/mandelbrot-fb.c
 | 
49
+++++++++++++++++++++++++++++++++++++++++++++++++
A
project/mandelbrot-fb.app.mk
 | 
7
+++++++

2 files changed, 56 insertions(+), 0 deletions(-)
diff --git a/misc/mandelbrot-fb.c b/misc/mandelbrot-fb.c
@@ -0,0 +1,49 @@
+// Copyright 2022, Brian Swetland <swetland@frotz.net>
+// Licensed under the Apache License, Version 2.0
+
+#include <string.h>
+#include <stdint.h>
+
+#include <hw/debug.h>
+#include <hw/platform.h>
+
+#define FB_WIDTH 640
+#define FB_HEIGHT 480
+
+unsigned colors[12] = {
+	0x00FF0000, 0x0000FF00, 0x000000FF,
+	0x00FFFF00, 0x0000FFFF, 0x00FF00FF,
+	0x00800000, 0x00008000, 0x00000080,
+	0x00808000, 0x00008080, 0x00800080,
+};
+
+static inline void plot(unsigned px, unsigned py, unsigned c) {
+	((unsigned volatile*) FRAMEBUFFER_BASE)[px + py * FB_WIDTH] = c;
+}
+
+void start(void) {
+	xputs("Hello, Mandelbrot!\n");
+
+	memset((void*) FRAMEBUFFER_BASE, 0, 640 * 480 * 4);
+
+	for (int py = 0; py < FB_HEIGHT; py++) {
+		int y0 = 1300 - (2600 * py) / FB_HEIGHT;
+		for (int px = 0; px < FB_WIDTH; px++) {
+			int x0 = -2500 + (3500 * px) / FB_WIDTH;
+			int x = 0, y = 0;
+			for (int i = 0; i < 1000; i++) {
+				int x2 = x * x / 1000;
+				int y2 = y * y / 1000;
+				if ((x2 + y2) > 4000) {
+					plot(px, py, colors[(i > 11) ? 11 : i]);
+					goto done;
+				}
+				y = 2 * x * y / 1000 + y0;
+				x = x2 - y2 + x0;
+			}
+			plot(px, py, 0);
+		done:
+			;
+		}
+	}
+}
diff --git a/project/mandelbrot-fb.app.mk b/project/mandelbrot-fb.app.mk
@@ -0,0 +1,7 @@
+
+MOD_NAME := mandelbrot-fb
+MOD_SRC := hw/src/start.S misc/mandelbrot-fb.c
+MOD_SRC += hw/src/debug.c
+MOD_QEMU_FB := 1
+MOD_LIB := c
+include make/app.mk