A blob to reproduce phil-opp/blog_os#403 (comment)

dummy.sh

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+#!/usr/bin/env bash
+# this file exists just because the only known way to create a custom "Run" command is run a bash script
+# Intellij - shame on you!
+
+$@

src/vga_buffer.rs

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+use core::fmt;
+use volatile::Volatile;
+
+const BUFFER_HEIGHT: usize = 25;
+const BUFFER_WIDTH: usize = 80;
+
+
+#[allow(dead_code)]
+#[derive(Debug, Clone, Copy)]
+#[repr(u8)]
+pub enum Color {
+    Black = 0,
+    Blue = 1,
+    Green = 2,
+    Cyan = 3,
+    Red = 4,
+    Magenta = 5,
+    Brown = 6,
+    LightGray = 7,
+    DarkGray = 8,
+    LightBlue = 9,
+    LightGreen = 10,
+    LightCyan = 11,
+    LightRed = 12,
+    Pink = 13,
+    Yellow = 14,
+    White = 15,
+}
+
+
+#[derive(Debug, Clone, Copy)]
+struct ColorCode(u8);
+
+impl ColorCode {
+    const fn new(foreground: Color, background: Color) -> ColorCode {
+        ColorCode((background as u8) << 4 | (foreground as u8))
+    }
+}
+
+
+#[derive(Debug, Clone, Copy)]
+#[repr(C)]
+struct ScreenChar {
+    ascii_character: u8,
+    color_code: ColorCode,
+}
+
+
+
+struct Buffer {
+    chars: [[Volatile<ScreenChar>; BUFFER_WIDTH]; BUFFER_HEIGHT],
+}
+
+
+pub struct Writer {
+    col_pos: usize,
+    row_pos: usize,
+    color_code: ColorCode,
+    buffer: &'static mut Buffer,
+}
+
+impl Writer {
+    pub fn write_byte(&mut self, byte: u8) {
+        match byte {
+            b'\n' => self.newline(),
+            byte => {
+                if self.col_pos >= BUFFER_WIDTH {
+                    self.newline();
+                }
+
+                let row = self.row_pos;
+                let col = self.col_pos;
+
+                self.buffer.chars[row][col].write(ScreenChar {
+                    ascii_character: byte,
+                    color_code: self.color_code,
+                });
+
+                self.col_pos += 1;
+            }
+        }
+    }
+
+    pub fn write_string(&mut self, s: &str) {
+        s.bytes().map(|byte| self.write_byte(byte));
+    }
+
+    pub fn newline(&mut self) {
+        self.col_pos = 0;
+
+        if self.row_pos == BUFFER_HEIGHT - 1 {
+            // move all the rows to one line up
+            // the first row (upper) is going to be overwritten
+            for row in 1..BUFFER_HEIGHT {
+                for col in 0..BUFFER_WIDTH {
+                    let ch = self.buffer.chars[row][col].read();
+                    self.buffer.chars[row - 1][col].write(ch);
+                }
+            }
+
+            // blank the last (bottom) row
+            for col in 0..BUFFER_HEIGHT {
+                let row = BUFFER_HEIGHT - 1;
+                let ch = ScreenChar { ascii_character: b' ', color_code: self.color_code };
+
+                self.buffer.chars[row][col].write(ch);
+            }
+        }
+        else {
+            self.row_pos += 1;
+        }
+    }
+}
+
+
+impl fmt::Write for Writer {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        self.write_string(s);
+        Ok(())
+    }
+}

x86_64-blog_os.json

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+{
+  "llvm-target": "x86_64-unknown-none",
+  "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
+  "arch": "x86_64",
+  "target-endian": "little",
+  "target-pointer-width": "64",
+  "target-c-int-width": "32",
+  "os": "none",
+  "executables": true,
+  "linker-flavor": "ld.lld",
+  "panic-strategy": "abort",
+  "disable-redzone": true,
+  "features": "-mmx,-sse,+soft-float"
+}