Add a global interface

Cargo.lock

@@ -13,6 +13,8 @@ name = "blog_os"
 version = "0.1.0"
 dependencies = [
  "bootloader 0.3.12 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "spin 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "volatile 0.2.6 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -63,6 +65,14 @@ dependencies = [
  "unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "lazy_static"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "spin 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "libc"
 version = "0.2.48"
@@ -131,6 +141,11 @@ dependencies = [
  "tempdir 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "spin"
+version = "0.4.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "tempdir"
 version = "0.3.7"
@@ -213,6 +228,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum fuchsia-zircon 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "2e9763c69ebaae630ba35f74888db465e49e259ba1bc0eda7d06f4a067615d82"
 "checksum fuchsia-zircon-sys 0.3.3 (registry+https://github.com/rust-lang/crates.io-index)" = "3dcaa9ae7725d12cdb85b3ad99a434db70b468c09ded17e012d86b5c1010f7a7"
 "checksum getopts 0.2.18 (registry+https://github.com/rust-lang/crates.io-index)" = "0a7292d30132fb5424b354f5dc02512a86e4c516fe544bb7a25e7f266951b797"
+"checksum lazy_static 1.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a374c89b9db55895453a74c1e38861d9deec0b01b405a82516e9d5de4820dea1"
 "checksum libc 0.2.48 (registry+https://github.com/rust-lang/crates.io-index)" = "e962c7641008ac010fa60a7dfdc1712449f29c44ef2d4702394aea943ee75047"
 "checksum os_bootinfo 0.2.1 (registry+https://github.com/rust-lang/crates.io-index)" = "66481dbeb5e773e7bd85b63cd6042c30786f834338288c5ec4f3742673db360a"
 "checksum pulldown-cmark 0.0.3 (registry+https://github.com/rust-lang/crates.io-index)" = "8361e81576d2e02643b04950e487ec172b687180da65c731c03cf336784e6c07"
@@ -222,6 +238,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 "checksum rdrand 0.4.0 (registry+https://github.com/rust-lang/crates.io-index)" = "678054eb77286b51581ba43620cc911abf02758c91f93f479767aed0f90458b2"
 "checksum remove_dir_all 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)" = "3488ba1b9a2084d38645c4c08276a1752dcbf2c7130d74f1569681ad5d2799c5"
 "checksum skeptic 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "061203a849117b0f7090baf8157aa91dac30545208fbb85166ac58b4ca33d89c"
+"checksum spin 0.4.10 (registry+https://github.com/rust-lang/crates.io-index)" = "ceac490aa12c567115b40b7b7fceca03a6c9d53d5defea066123debc83c5dc1f"
 "checksum tempdir 0.3.7 (registry+https://github.com/rust-lang/crates.io-index)" = "15f2b5fb00ccdf689e0149d1b1b3c03fead81c2b37735d812fa8bddbbf41b6d8"
 "checksum unicode-width 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)" = "882386231c45df4700b275c7ff55b6f3698780a650026380e72dabe76fa46526"
 "checksum usize_conversions 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "f70329e2cbe45d6c97a5112daad40c34cd9a4e18edb5a2a18fefeb584d8d25e5"

Cargo.toml

@@ -7,6 +7,11 @@ edition = "2018"
 [dependencies]
 bootloader = "0.3.12"
 volatile = "0.2.3"
+spin = "0.4.9"
+
+[dependencies.lazy_static]
+version = "1.0"
+features = ["spin_no_std"]
 
 [profile.dev]
 panic = "abort"

src/main.rs

@@ -7,7 +7,15 @@ mod vga_buffer;
 
 #[no_mangle]
 pub extern "C" fn _start() -> ! {
-    vga_buffer::print_something();
+    use core::fmt::Write;
+    vga_buffer::WRITER.lock().write_str("Hello again").unwrap();
+    write!(
+        vga_buffer::WRITER.lock(),
+        ", some numbers: {} {}",
+        42,
+        1.337
+    )
+    .unwrap();
 
     loop {}
 }

src/vga_buffer.rs

@@ -1,6 +1,16 @@
 use core::fmt;
+use lazy_static::lazy_static;
+use spin::Mutex;
 use volatile::Volatile;
 
+lazy_static! {
+    pub static ref WRITER: Mutex<Writer> = Mutex::new(Writer {
+        column_position: 0,
+        color_code: ColorCode::new(Color::Yellow, Color::Black),
+        buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
+    });
+}
+
 #[allow(dead_code)]
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 #[repr(u8)]
@@ -113,16 +123,3 @@ impl fmt::Write for Writer {
         Ok(())
     }
 }
-
-pub fn print_something() {
-    use core::fmt::Write;
-    let mut writer = Writer {
-        column_position: 0,
-        color_code: ColorCode::new(Color::Yellow, Color::Black),
-        buffer: unsafe { &mut *(0xb8000 as *mut Buffer) },
-    };
-
-    writer.write_byte(b'H');
-    writer.write_string("ello! ");
-    write!(writer, "The numbers are {} and {}", 42, 1.0 / 3.0).unwrap();
-}