From 1645da679ce50b13b6f19a062eabd2d869762a07 Mon Sep 17 00:00:00 2001
From: Nathan Reiner <nathan@nathanreiner.xyz>
Date: Wed, 15 Feb 2023 15:07:56 +0100
Subject: add framebuffer image support

---
 lib/fb/fb.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/fb/fb.h |  26 ++++++++++++
 2 files changed, 154 insertions(+)
 create mode 100644 lib/fb/fb.c
 create mode 100644 lib/fb/fb.h

(limited to 'lib/fb')

diff --git a/lib/fb/fb.c b/lib/fb/fb.c
new file mode 100644
index 0000000..aabe86e
--- /dev/null
+++ b/lib/fb/fb.c
@@ -0,0 +1,128 @@
+#include "fb.h"
+
+#include "../sys/mmap.h"
+#include "../sys/munmap.h"
+#include "../io/io.h"
+#include "../sys/ioctl.h"
+#include "../sys/errno.h"
+
+#define FBIOGET_VSCREENINFO 0x4600
+#define FBIOGET_FSCREENINFO 0x4602
+
+typedef struct {
+	char id[16];
+	unsigned long smem_start;
+	u32 smem_len;
+	u32 type;
+	u32 type_aux;
+	u32 visual;
+	u16 xpanstep;
+	u16 ypanstep;
+	u16 ywrapstep;
+	u32 line_length;
+	unsigned long mmio_start;
+	u32 mmio_len;
+	u32 accel;
+	u16 capabilities;
+	u16 reserved[2];
+} fb_fscreeninfo_t;
+
+typedef struct {
+	u32 offset;
+	u32 length;
+	u32 msb_right;
+} fb_bitfield_t;
+
+typedef struct {
+	u32 xres;
+	u32 yres;
+	u32 xres_virtual;
+	u32 yres_virtual;
+	u32 xoffset;
+	u32 yoffset;
+
+	u32 bits_per_pixel;
+	u32 grayscale;
+
+	fb_bitfield_t red;
+	fb_bitfield_t green;
+	fb_bitfield_t blue;
+	fb_bitfield_t transp;
+
+	u32 nonstd;
+
+	u32 activate;
+
+	u32 height;
+	u32 width;
+
+	u32 accel_flags;
+
+	u32 pixclock;
+	u32 left_margin;
+	u32 right_margin;
+	u32 upper_margin;
+	u32 lower_margin;
+	u32 hsync_len;
+	u32 vsync_len;
+	u32 sync;
+	u32 vmode;
+	u32 rotate;
+	u32 colorspace;
+	u32 reserved[4];
+} fb_vscreeninfo_t;
+
+int fbfd = 0;
+
+
+canvas_t open_framebuffer()
+{
+	fb_vscreeninfo_t vinfo;
+	fb_fscreeninfo_t finfo;
+	canvas_t canvas = { 0, 0, 0 };
+
+	fbfd = open("/system/devices/fb0", OPEN_READ_WRITE, 0);
+
+	if (fbfd < 0)
+		return canvas;
+
+	
+	if (ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo) != 0)
+		return canvas;
+
+	if (ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo) != 0)
+		return canvas;
+	
+	canvas.width = vinfo.xres;
+	canvas.height = vinfo.yres;
+	canvas.bits_per_pixel = vinfo.bits_per_pixel;
+	canvas.line_length = finfo.line_length;
+
+	canvas.data = (canvas_pixel_t*)mmap(0, sizeof(u32) * canvas.width * canvas.height,
+	                                    PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
+
+	if ((i64)canvas.data < 0) {
+		wff(STDERR_FD, "error: %s\n", errstr[-(i64)canvas.data]);
+		canvas.data = 0;
+		canvas.width = 0;
+		canvas.height = 0;
+		return canvas;
+	}
+
+	return canvas;
+}
+
+
+void close_framebuffer(canvas_t canvas)
+{
+	munmap(canvas.data, sizeof(u32) * canvas.width * canvas.height);
+	close(fbfd);
+}
+
+
+void put_pixel(canvas_t canvas, u64 x, u64 y, canvas_pixel_t p)
+{
+	char *pos = (char*)canvas.data;
+	pos += (x * canvas.bits_per_pixel / 8) + (y * canvas.line_length);
+	*((canvas_pixel_t*) pos) = p;
+}
diff --git a/lib/fb/fb.h b/lib/fb/fb.h
new file mode 100644
index 0000000..a11f29f
--- /dev/null
+++ b/lib/fb/fb.h
@@ -0,0 +1,26 @@
+#ifndef FB_H
+#define FB_H
+
+#include "../sys/types.h"
+
+typedef struct {
+	u8 b;
+	u8 g;
+	u8 r;
+	u8 a;
+} canvas_pixel_t;
+
+typedef struct {
+	u32 width;
+	u32 height;
+	canvas_pixel_t *data;
+	u32 line_length;
+	u32 bits_per_pixel;
+} canvas_t;
+
+canvas_t open_framebuffer();
+void close_framebuffer(canvas_t);
+
+void put_pixel(canvas_t canvas, u64 x, u64 y, canvas_pixel_t p);
+
+#endif
-- 
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