Merge rust-osdev#35

35: Add support for 320x200 256 color VGA video mode  r=phil-opp a=phil-opp



Co-authored-by: Philipp Oppermann <[email protected]>

Author: bors[bot]

.travis.yml

@@ -41,3 +41,5 @@ script:
 - cd example-kernel; cargo xbuild --target x86_64-example-kernel.json; cd ..
 - cd builder; cargo run -- --kernel ../example-kernel/target/x86_64-example-kernel/debug/example-kernel; cd ..
 - qemu-system-x86_64 -drive format=raw,file=target/x86_64-bootloader/release/bootimage.bin -device isa-debug-exit,iobase=0xf4,iosize=0x04 -display none; if [ $? -eq 123 ]; then (exit 0); else (exit 1); fi
+- cd builder; cargo run -- --kernel ../example-kernel/target/x86_64-example-kernel/debug/example-kernel --features vga_320x200; cd ..
+- qemu-system-x86_64 -drive format=raw,file=target/x86_64-bootloader/release/bootimage.bin -device isa-debug-exit,iobase=0xf4,iosize=0x04 -display none; if [ $? -eq 123 ]; then (exit 0); else (exit 1); fi

Cargo.lock

@@ -15,6 +15,15 @@ x86_64 = "0.2.7"
 usize_conversions = "0.2.0"
 fixedvec = "0.2.3"
 
+[dependencies.font8x8]
+version = "0.2.4"
+default-features = false
+features = ["unicode"]
+
+[features]
+default = []
+vga_320x200 = []
+
 [profile.dev]
 panic = "abort"
 

Cargo.toml

@@ -35,3 +35,8 @@ dd if=target/x86_64-blog_os/debug/bootimage-blog_os.bin of=/dev/sdX && sync
 ```
 
 Where sdX is the device name of your USB stick. **Be careful** to choose the correct device name, because everything on that device is overwritten.
+
+## Features
+The bootloader crate can be configured through some cargo features:
+
+- `vga_320x200`: This feature switches the VGA hardware to mode 0x13, a graphics mode with resolution 320x200 and 256 colors per pixel. The framebuffer is linear and lives at address `0xa0000`.

README.md

@@ -0,0 +1,3 @@
+status = [
+    "continuous-integration/travis-ci/push"
+]

bors.toml

@@ -14,6 +14,7 @@ extern crate x86_64;
 extern crate xmas_elf;
 #[macro_use]
 extern crate fixedvec;
+extern crate font8x8;
 
 use bootloader::bootinfo::BootInfo;
 use core::panic::PanicInfo;
@@ -32,6 +33,11 @@ global_asm!(include_str!("stage_3.s"));
 global_asm!(include_str!("stage_4.s"));
 global_asm!(include_str!("context_switch.s"));
 
+#[cfg(feature = "vga_320x200")]
+global_asm!(include_str!("video_mode/vga_320x200.s"));
+#[cfg(not(feature = "vga_320x200"))]
+global_asm!(include_str!("video_mode/vga_text_80x25.s"));
+
 extern "C" {
     fn context_switch(boot_info: VirtAddr, entry_point: VirtAddr, stack_pointer: VirtAddr) -> !;
 }

src/main.rs

@@ -0,0 +1,8 @@
+#[cfg(not(feature = "vga_320x200"))]
+pub use self::vga_text_80x25::*;
+
+#[cfg(feature = "vga_320x200")]
+pub use self::vga_320x200::*;
+
+mod vga_text_80x25;
+mod vga_320x200;

src/printer/mod.rs

@@ -0,0 +1,81 @@
+use core::fmt::{Result, Write};
+use core::slice;
+use core::sync::atomic::{AtomicUsize, Ordering};
+
+const VGA_BUFFER: *mut u8 = 0xa0000 as *mut _;
+const SCREEN_WIDTH: usize = 320;
+const SCREEN_HEIGHT: usize = 200;
+
+pub static X_POS: AtomicUsize = AtomicUsize::new(1); // must not be 0 so that we don't have a .bss section
+pub static Y_POS: AtomicUsize = AtomicUsize::new(1); // must not be 0 so that we don't have a .bss section
+
+pub struct Printer;
+
+impl Printer {
+    pub fn clear_screen(&mut self) {
+        let vga_buffer = Self::vga_buffer();
+        for byte in vga_buffer {
+            *byte = 0x00;
+        }
+        X_POS.store(0, Ordering::SeqCst);
+        Y_POS.store(0, Ordering::SeqCst);
+    }
+
+    fn vga_buffer() -> &'static mut [u8] {
+        unsafe { slice::from_raw_parts_mut(VGA_BUFFER, SCREEN_WIDTH * SCREEN_HEIGHT) }
+    }
+
+    fn newline(&mut self) {
+        let y_pos = Y_POS.fetch_add(8, Ordering::SeqCst);
+        X_POS.store(0, Ordering::SeqCst);
+        if y_pos >= SCREEN_HEIGHT {
+            self.clear_screen();
+        }
+    }
+
+    fn write_char(&mut self, c: char) {
+        use font8x8::{self, UnicodeFonts};
+
+        if c == '\n' {
+            self.newline();
+            return;
+        }
+
+        let vga_buffer = Self::vga_buffer();
+
+        let x_pos = X_POS.fetch_add(8, Ordering::SeqCst);
+        let y_pos = Y_POS.load(Ordering::SeqCst);
+
+        match c {
+            ' '..='~' => {
+                let rendered = font8x8::BASIC_FONTS
+                    .get(c)
+                    .expect("character not found in basic font");
+                for (y, byte) in rendered.iter().enumerate() {
+                    for (x, bit) in (0..8).enumerate() {
+                        if *byte & (1 << bit) == 0 {
+                            continue
+                        }
+                        let color = 0xf;
+                        vga_buffer[(y_pos + y) * SCREEN_WIDTH + x_pos + x] = color;
+                    }
+                }
+            }
+            _ => panic!("unprintable character"),
+        }
+
+        if x_pos + 8 >= SCREEN_WIDTH {
+            self.newline();
+        }
+    }
+}
+
+impl Write for Printer {
+    fn write_str(&mut self, s: &str) -> Result {
+        for c in s.chars() {
+            self.write_char(c);
+        }
+
+        Ok(())
+    }
+}

src/printer/vga_320x200.rs

@@ -23,7 +23,7 @@ _start:
     mov sp, 0x7c00
 
     lea si, boot_start_str
-    call println
+    call real_mode_println
 
 enable_a20:
     # enable A20-Line via IO-Port 92, might not work on all motherboards
@@ -107,38 +107,38 @@ spin:
 #   esi: points at zero-terminated String
 # CLOBBER
 #   ax
-println:
-    call print
+real_mode_println:
+    call real_mode_print
     mov al, 13 # \r
-    call print_char
+    call real_mode_print_char
     mov al, 10 # \n
-    jmp print_char
+    jmp real_mode_print_char
 
 # print a string
 # IN
 #   esi: points at zero-terminated String
 # CLOBBER
 #   ax
-print:
+real_mode_print:
     cld
-print_loop:
+real_mode_print_loop:
     # note: if direction flag is set (via std)
     # this will DECREMENT the ptr, effectively
     # reading/printing in reverse.
     lodsb al, BYTE PTR [esi]
     test al, al
-    jz print_done
-    call print_char
-    jmp print_loop
-print_done:
+    jz real_mode_print_done
+    call real_mode_print_char
+    jmp real_mode_print_loop
+real_mode_print_done:
     ret
 
 # print a character
 # IN
 #   al: character to print
 # CLOBBER
 #   ah
-print_char:
+real_mode_print_char:
     mov ah, 0x0e
     int 0x10
     ret
@@ -148,7 +148,7 @@ print_char:
 #   bx: the number
 # CLOBBER
 #   al, cx
-print_hex:
+real_mode_print_hex:
     mov cx, 4
 .lp:
     mov al, bh
@@ -161,28 +161,27 @@ print_hex:
 .below_0xA:
     add al, '0'
 
-    call print_char
+    call real_mode_print_char
 
     shl bx, 4
     loop .lp
 
     ret
 
-error:
-    call println
+real_mode_error:
+    call real_mode_println
     jmp spin
 
 no_int13h_extensions:
     lea si, no_int13h_extensions_str
-    jmp error
+    jmp real_mode_error
 
 rest_of_bootloader_load_failed:
     lea si, rest_of_bootloader_load_failed_str
-    jmp error
+    jmp real_mode_error
 
 boot_start_str: .asciz "Booting (first stage)..."
 error_str: .asciz "Error: "
-no_cpuid_str: .asciz "No CPUID support"
 no_int13h_extensions_str: .asciz "No support for int13h extensions"
 rest_of_bootloader_load_failed_str: .asciz "Failed to load rest of bootloader"