examples: add initial video buffer no-std demo

Author: Qix-

.cargo/config.toml

@@ -22,4 +22,4 @@ oro-ra-x86_64 = "check --quiet --message-format=json --keep-going --target ./oro
 oro-ra-aarch64 = "check --quiet --message-format=json --keep-going --target ./oro-arch-aarch64/aarch64-unknown-oro.json --bin oro-kernel-aarch64 --bin oro-limine-aarch64 -Zunstable-options -Zbuild-std=core,compiler_builtins,alloc -Zbuild-std-features=compiler-builtins-mem"
 
 # NOTE: Does not need the unstable flags / building std / etc.
-oro-examples = "build --target=x86_64-unknown-none --target=aarch64-unknown-none -p example-noop -p example-spin -p example-std-noop -p example-std-noop-nightly -p example-std-spin -p example-hello-world"
+oro-examples = "build --target=x86_64-unknown-none --target=aarch64-unknown-none -p example-noop -p example-spin -p example-std-noop -p example-std-noop-nightly -p example-std-spin -p example-hello-world -p example-root-vbuf-demo"

Cargo.lock

@@ -36,6 +36,7 @@ members = [
 	"examples/no-std/noop",
 	"examples/no-std/spin",
 	"examples/no-std/hello-world",
+	"examples/no-std/root-vbuf-demo",
 	"examples/std/noop",
 	"examples/std/noop-nightly",
 	"examples/std/spin",

Cargo.toml

@@ -0,0 +1,17 @@
+[package]
+name = "example-root-vbuf-demo"
+description = "Example module that shows how to work with the ROOT_BOOT_VBUF_V0 interface."
+version = "0.0.0"
+publish = false
+edition = "2021"
+
+build = "build.rs"
+
+[dependencies.oro]
+path = "../../../oro"
+features = ["runtime"]
+
+[build-dependencies.oro]
+path = "../../../oro"
+features = ["build"]
+default-features = false

examples/no-std/root-vbuf-demo/Cargo.toml

@@ -0,0 +1,3 @@
+fn main() {
+	::oro::build();
+}

examples/no-std/root-vbuf-demo/build.rs

@@ -0,0 +1,100 @@
+#![no_std]
+#![no_main]
+
+use oro::{
+	id::kernel::iface::{ROOT_BOOT_VBUF_V0, ROOT_DEBUG_OUT_V0},
+	syscall,
+};
+
+fn write_bytes(bytes: &[u8]) {
+	if bytes.len() == 0 {
+		return;
+	}
+
+	for chunk in bytes.chunks(8) {
+		let mut word = 0u64;
+		for b in chunk {
+			word = (word << 8) | *b as u64;
+		}
+
+		// XXX(qix-): Hard coding the ID for a moment, bear with.
+		syscall::set!(
+			ROOT_DEBUG_OUT_V0,
+			4294967296,
+			0,
+			syscall::key!("write"),
+			word
+		)
+		.unwrap();
+	}
+}
+
+fn write_str(s: &str) {
+	write_bytes(s.as_bytes());
+}
+
+struct Vbuf {
+	width:          u64,
+	height:         u64,
+	stride:         u64,
+	bits_per_pixel: u64,
+	data:           *mut u8,
+}
+
+fn find_video_buffer(idx: u64) -> Result<Vbuf, (oro::sysabi::syscall::Error, u64)> {
+	macro_rules! get_vbuf_field {
+		($field:literal) => {{
+			syscall::get!(
+				ROOT_BOOT_VBUF_V0,
+				// XXX(qix-): Hardcoding the ID for now, bear with.
+				4294967297,
+				idx,
+				syscall::key!($field),
+			)?
+		}};
+	}
+
+	let vbuf_addr: u64 = 0x60000000000 + (idx as u64) * 0x100000000;
+
+	Ok(Vbuf {
+		width:          get_vbuf_field!("width"),
+		height:         get_vbuf_field!("height"),
+		stride:         get_vbuf_field!("pitch"),
+		bits_per_pixel: get_vbuf_field!("bit_pp"),
+		data:           {
+			syscall::set!(
+				ROOT_BOOT_VBUF_V0,
+				// XXX(qix-): Hardcoding the ID for now, bear with.
+				4294967297,
+				idx,
+				syscall::key!("!vmbase!"),
+				vbuf_addr
+			)?;
+
+			vbuf_addr as *mut u8
+		},
+	})
+}
+
+#[no_mangle]
+fn main() {
+	write_str("looking for vbuf 0...\n");
+	if let Ok(vbuf) = find_video_buffer(0) {
+		write_str("found vbuf 0\n");
+		let bytes_per_pixel = vbuf.bits_per_pixel / 8;
+		for y in 0..vbuf.height {
+			for x in 0..(vbuf.width * bytes_per_pixel) {
+				unsafe {
+					*vbuf.data.offset(((y * vbuf.stride) + x) as isize) =
+						if (((x + y) % 5) as u8) == 0 {
+							0xFF
+						} else {
+							0x00
+						};
+				}
+			}
+		}
+	} else {
+		write_str("failed to find vbuf 0\n");
+	}
+}