simple gui app can run now!

user/src/bin/gui_simple.rs

@@ -0,0 +1,35 @@
+#![no_std]
+#![no_main]
+
+use user_lib::{framebuffer, framebuffer_flush};
+
+#[macro_use]
+extern crate user_lib;
+
+// use embedded_graphics::pixelcolor::Rgb888;
+// use embedded_graphics::prelude::{Drawable, Point, RgbColor, Size};
+// use embedded_graphics::primitives::Primitive;
+// use embedded_graphics::primitives::{PrimitiveStyle, Rectangle};
+// use embedded_graphics::{
+//     draw_target::DrawTarget,
+//     prelude::{OriginDimensions},
+// };
+pub const VIRTGPU_XRES: usize = 1280;
+pub const VIRTGPU_YRES: usize = 800;
+
+#[no_mangle]
+pub fn main() -> i32 {
+    let fb_ptr =framebuffer() as *mut u8;
+    println!("Hello world from user mode program! 0x{:X} , len {}", fb_ptr as usize, VIRTGPU_XRES*VIRTGPU_YRES*4);
+    let fb= unsafe {core::slice::from_raw_parts_mut(fb_ptr as *mut u8, VIRTGPU_XRES*VIRTGPU_YRES*4 as usize)};
+    for y in 0..800 {
+        for x in 0..1280 {
+            let idx = (y * 1280 + x) * 4;
+            fb[idx] = x as u8;
+            fb[idx + 1] = y as u8;
+            fb[idx + 2] = (x + y) as u8;
+        }
+    }
+    framebuffer_flush();
+    0
+}