1 files changed, 157 insertions, 0 deletions
diff --git a/src/codes.rs b/src/codes.rs
new file mode 100644
index 0000000..2111df7
--- /dev/null
+++ b/src/codes.rs
@@ -0,0 +1,157 @@
+use std::io::{Error, ErrorKind, Result, Write};
+
+const ESCAPE_CODE: &[u8] = "\x1b[L".as_bytes();
+const GENERATOR_MAX_CHAR_INDEX: u8 = 7;
+
+macro_rules! write_char {
+    ($writer:ident, $char:expr) => {
+        $writer.write(&[$char as u8])
+    };
+}
+
+macro_rules! write_digit {
+    ($writer:ident, $num:expr) => {
+        $writer.write(&[$num + '0' as u8])
+    };
+}
+
+pub trait WriteInto<W>
+where
+    W: Write,
+{
+    fn write_into(self, writer: &mut W) -> Result<usize>;
+}
+
+pub enum SpecialCode {
+    DisplayOn,
+    DisplayOff,
+    CursorOn,
+    CursorOff,
+    BlinkOn,
+    BlinkOff,
+    BacklightOn,
+    BacklightOff,
+    FlashBacklight,
+    SmallFont,
+    LargeFont,
+    OneLine,
+    TwoLines,
+    ShiftCursorLeft,
+    ShiftCursorRight,
+    ShiftDisplayLeft,
+    ShiftDisplayRight,
+    KillEndOfLine,
+    ReinitializeDisplay,
+    Generator(u8, u64),
+    GotoXY(Option<u32>, Option<u32>),
+}
+
+fn write_goto_xy_sym<T: Write>(writer: &mut T, sym: char, value: Option<u32>) -> Result<usize> {
+    let mut total = 0;
+    if let Some(value) = value {
+        total += write_char!(writer, sym)?;
+        total += writer.write(value.to_string().as_bytes())?;
+    }
+    Ok(total)
+}
+
+fn write_goto_xy<T: Write>(writer: &mut T, x: Option<u32>, y: Option<u32>) -> Result<usize> {
+    let mut total = 0;
+    total += write_goto_xy_sym(writer, 'x', x)?;
+    total += write_goto_xy_sym(writer, 'y', y)?;
+    total += write_char!(writer, ';')?;
+    Ok(total)
+}
+
+fn write_generator<T: Write>(writer: &mut T, char_index: u8, value: u64) -> Result<usize> {
+    if char_index > GENERATOR_MAX_CHAR_INDEX {
+        return Err(Error::new(
+            ErrorKind::Other,
+            format!(
+                "char index cannot be greater than {}",
+                GENERATOR_MAX_CHAR_INDEX
+            ),
+        ));
+    }
+
+    let mut total = 0;
+    total += write_char!(writer, 'G')?;
+    total += write_digit!(writer, char_index)?;
+    total += writer.write(format!("{:>016x}", value).as_bytes())?;
+    total += write_char!(writer, ';')?;
+    Ok(total)
+}
+
+impl<W> WriteInto<W> for SpecialCode
+where
+    W: Write,
+{
+    fn write_into(self, writer: &mut W) -> Result<usize> {
+        let mut total = 0;
+
+        total += writer.write(ESCAPE_CODE)?;
+        total += match self {
+            SpecialCode::DisplayOn => write_char!(writer, 'D')?,
+            SpecialCode::DisplayOff => write_char!(writer, 'd')?,
+            SpecialCode::CursorOn => write_char!(writer, 'C')?,
+            SpecialCode::CursorOff => write_char!(writer, 'c')?,
+            SpecialCode::BlinkOn => write_char!(writer, 'B')?,
+            SpecialCode::BlinkOff => write_char!(writer, 'b')?,
+            SpecialCode::BacklightOn => write_char!(writer, '+')?,
+            SpecialCode::BacklightOff => write_char!(writer, '-')?,
+            SpecialCode::FlashBacklight => write_char!(writer, '*')?,
+            SpecialCode::SmallFont => write_char!(writer, 'f')?,
+            SpecialCode::LargeFont => write_char!(writer, 'F')?,
+            SpecialCode::OneLine => write_char!(writer, 'n')?,
+            SpecialCode::TwoLines => write_char!(writer, 'N')?,
+            SpecialCode::ShiftCursorLeft => write_char!(writer, 'l')?,
+            SpecialCode::ShiftCursorRight => write_char!(writer, 'r')?,
+            SpecialCode::ShiftDisplayLeft => write_char!(writer, 'L')?,
+            SpecialCode::ShiftDisplayRight => write_char!(writer, 'R')?,
+            SpecialCode::KillEndOfLine => write_char!(writer, 'k')?,
+            SpecialCode::ReinitializeDisplay => write_char!(writer, 'I')?,
+            SpecialCode::GotoXY(x, y) => write_goto_xy(writer, x, y)?,
+            SpecialCode::Generator(c, x) => write_generator(writer, c, x)?,
+        };
+
+        Ok(total)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn assert_code_eq(code: SpecialCode, expected: &str) {
+        use std::io::Cursor;
+        let mut buf = Cursor::new(Vec::new());
+        let count = code.write_into(&mut buf).unwrap();
+        let expected = expected.as_bytes();
+
+        assert_eq!(count, expected.len());
+        assert_eq!(&buf.get_ref()[0..count], expected);
+    }
+
+    #[test]
+    fn simple_codes() {
+        assert_code_eq(SpecialCode::DisplayOff.into(), "\x1b[Ld");
+        assert_code_eq(SpecialCode::DisplayOn.into(), "\x1b[LD");
+    }
+
+    #[test]
+    fn special_code_goto_xy() {
+        assert_code_eq(SpecialCode::GotoXY(None, None), "\x1b[L;");
+        assert_code_eq(SpecialCode::GotoXY(Some(42), None), "\x1b[Lx42;");
+        assert_code_eq(SpecialCode::GotoXY(None, Some(42)), "\x1b[Ly42;");
+        assert_code_eq(SpecialCode::GotoXY(Some(42), Some(32)), "\x1b[Lx42y32;");
+    }
+
+    #[test]
+    fn special_code_gen() {
+        assert_code_eq(
+            SpecialCode::Generator(7, 0xdeadbeefdecacafe),
+            "\x1b[LG7deadbeefdecacafe;",
+        );
+        assert_code_eq(SpecialCode::Generator(7, 0xff), "\x1b[LG700000000000000ff;");
+    }
+}