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/// Determines if the cursor should be incremented or decremented on write
#[derive(Debug, PartialEq, Eq)]
pub enum CursorMode {
Increment,
Decrement,
}
impl Default for CursorMode {
fn default() -> CursorMode {
CursorMode::Increment
}
}
/// Determines if the screen should be shifted on write
#[derive(Debug, PartialEq, Eq)]
pub enum ShiftMode {
Enabled,
Disabled,
}
impl From<bool> for ShiftMode {
fn from(b: bool) -> ShiftMode {
if b {
ShiftMode::Enabled
} else {
ShiftMode::Disabled
}
}
}
impl Default for ShiftMode {
fn default() -> ShiftMode {
ShiftMode::Disabled
}
}
#[derive(Default)]
pub struct EntryMode {
pub cursor_mode: CursorMode,
pub shift_mode: ShiftMode,
}
impl EntryMode {
pub fn as_byte(&self) -> u8 {
let cursor_bits = match self.cursor_mode {
CursorMode::Increment => 0b0000_0010,
CursorMode::Decrement => 0,
};
let shift_bits = match self.shift_mode {
ShiftMode::Enabled => 0b0000_0001,
ShiftMode::Disabled => 0,
};
0b0000_0100 | cursor_bits | shift_bits
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn cursor_mode() {
let em = EntryMode {
cursor_mode: CursorMode::Increment,
shift_mode: Default::default(),
};
assert!(em.as_byte() & 0b0000_0010 != 0);
let em = EntryMode {
cursor_mode: CursorMode::Decrement,
shift_mode: Default::default(),
};
assert!(em.as_byte() & 0b0000_0010 == 0);
}
#[test]
fn shift_mode() {
let em = EntryMode {
cursor_mode: Default::default(),
shift_mode: ShiftMode::Enabled,
};
assert!(em.as_byte() & 0b0000_0001 != 0);
let em = EntryMode {
cursor_mode: Default::default(),
shift_mode: ShiftMode::Disabled,
};
assert!(em.as_byte() & 0b0000_0001 == 0);
}
}
|
