Get rid of generic-array (#158)

* Get rid of generic-array

* State MSRV bump and adjust Buffer types

CHANGELOG.md

@@ -6,6 +6,10 @@
 
 ## [Unreleased] - ReleaseDate
 
+### Changed
+
+- **(breaking)** [#158](https://github.com/jamwaffles/ssd1306/pull/158) Migrate away from `generic-array` to a solution using const generics. This raises the crate MSRV to 1.51.
+
 ## [0.6.0] - 2021-06-22
 
 ### Changed

Cargo.toml

@@ -23,7 +23,6 @@ embedded-hal = "0.2.5"
 display-interface = "0.4.1"
 display-interface-i2c = "0.4.0"
 display-interface-spi = "0.4.1"
-generic-array = "0.14.4"
 embedded-graphics-core = { version = "0.3.2", optional = true }
 
 [dev-dependencies]

src/mode/buffered_graphics.rs

@@ -1,8 +1,12 @@
 //! Buffered graphics mode.
 
-use crate::{command::AddrMode, rotation::DisplayRotation, size::DisplaySize, Ssd1306};
+use crate::{
+    command::AddrMode,
+    rotation::DisplayRotation,
+    size::{DisplaySize, NewZeroed},
+    Ssd1306,
+};
 use display_interface::{DisplayError, WriteOnlyDataCommand};
-use generic_array::GenericArray;
 
 /// Buffered graphics mode.
 ///
@@ -15,7 +19,7 @@ pub struct BufferedGraphicsMode<SIZE>
 where
     SIZE: DisplaySize,
 {
-    buffer: GenericArray<u8, SIZE::BufferSize>,
+    buffer: SIZE::Buffer,
     min_x: u8,
     max_x: u8,
     min_y: u8,
@@ -29,7 +33,7 @@ where
     /// Create a new buffered graphics mode instance.
     pub(crate) fn new() -> Self {
         Self {
-            buffer: GenericArray::default(),
+            buffer: NewZeroed::new_zeroed(),
             min_x: 255,
             max_x: 0,
             min_y: 255,
@@ -66,7 +70,9 @@ where
 {
     /// Clear the display buffer. You need to call `disp.flush()` for any effect on the screen
     pub fn clear(&mut self) {
-        self.mode.buffer = GenericArray::default();
+        for b in self.mode.buffer.as_mut() {
+            *b = 0;
+        }
 
         let (width, height) = self.dimensions();
         self.mode.min_x = 0;
@@ -125,7 +131,7 @@ where
 
                 Self::flush_buffer_chunks(
                     &mut self.interface,
-                    &self.mode.buffer,
+                    self.mode.buffer.as_mut(),
                     width as usize,
                     (disp_min_x, disp_min_y),
                     (disp_max_x, disp_max_y),
@@ -139,7 +145,7 @@ where
 
                 Self::flush_buffer_chunks(
                     &mut self.interface,
-                    &self.mode.buffer,
+                    self.mode.buffer.as_mut(),
                     height as usize,
                     (disp_min_y, disp_min_x),
                     (disp_max_y, disp_max_x),
@@ -169,7 +175,7 @@ where
             }
         };
 
-        if let Some(byte) = self.mode.buffer.get_mut(idx) {
+        if let Some(byte) = self.mode.buffer.as_mut().get_mut(idx) {
             // Keep track of max and min values
             self.mode.min_x = self.mode.min_x.min(x as u8);
             self.mode.max_x = self.mode.max_x.max(x as u8);

src/size.rs

@@ -2,10 +2,18 @@
 
 use super::command::Command;
 use display_interface::{DisplayError, WriteOnlyDataCommand};
-use generic_array::{
-    typenum::{U1024, U192, U360, U384, U512},
-    ArrayLength,
-};
+
+/// Workaround trait, since `Default` is only implemented to arrays up to 32 of size
+pub trait NewZeroed {
+    /// Creates a new value with its memory set to zero
+    fn new_zeroed() -> Self;
+}
+
+impl<const N: usize> NewZeroed for [u8; N] {
+    fn new_zeroed() -> Self {
+        [0u8; N]
+    }
+}
 
 /// Display information.
 ///
@@ -32,7 +40,7 @@ pub trait DisplaySize {
 
     /// Size of framebuffer. Because the display is monocrome, this is
     /// width * height / 8
-    type BufferSize: ArrayLength<u8>;
+    type Buffer: AsMut<[u8]> + NewZeroed;
 
     /// Send resolution and model-dependent configuration to the display
     ///
@@ -48,7 +56,7 @@ pub struct DisplaySize128x64;
 impl DisplaySize for DisplaySize128x64 {
     const WIDTH: u8 = 128;
     const HEIGHT: u8 = 64;
-    type BufferSize = U1024;
+    type Buffer = [u8; Self::WIDTH as usize * Self::HEIGHT as usize / 8];
 
     fn configure(&self, iface: &mut impl WriteOnlyDataCommand) -> Result<(), DisplayError> {
         Command::ComPinConfig(true, false).send(iface)
@@ -61,7 +69,7 @@ pub struct DisplaySize128x32;
 impl DisplaySize for DisplaySize128x32 {
     const WIDTH: u8 = 128;
     const HEIGHT: u8 = 32;
-    type BufferSize = U512;
+    type Buffer = [u8; Self::WIDTH as usize * Self::HEIGHT as usize / 8];
 
     fn configure(&self, iface: &mut impl WriteOnlyDataCommand) -> Result<(), DisplayError> {
         Command::ComPinConfig(false, false).send(iface)
@@ -74,7 +82,7 @@ pub struct DisplaySize96x16;
 impl DisplaySize for DisplaySize96x16 {
     const WIDTH: u8 = 96;
     const HEIGHT: u8 = 16;
-    type BufferSize = U192;
+    type Buffer = [u8; Self::WIDTH as usize * Self::HEIGHT as usize / 8];
 
     fn configure(&self, iface: &mut impl WriteOnlyDataCommand) -> Result<(), DisplayError> {
         Command::ComPinConfig(false, false).send(iface)
@@ -89,7 +97,7 @@ impl DisplaySize for DisplaySize72x40 {
     const HEIGHT: u8 = 40;
     const OFFSETX: u8 = 28;
     const OFFSETY: u8 = 0;
-    type BufferSize = U360;
+    type Buffer = [u8; Self::WIDTH as usize * Self::HEIGHT as usize / 8];
 
     fn configure(&self, iface: &mut impl WriteOnlyDataCommand) -> Result<(), DisplayError> {
         Command::ComPinConfig(true, false).send(iface)?;
@@ -105,7 +113,7 @@ impl DisplaySize for DisplaySize64x48 {
     const HEIGHT: u8 = 48;
     const OFFSETX: u8 = 32;
     const OFFSETY: u8 = 0;
-    type BufferSize = U384;
+    type Buffer = [u8; Self::WIDTH as usize * Self::HEIGHT as usize / 8];
 
     fn configure(&self, iface: &mut impl WriteOnlyDataCommand) -> Result<(), DisplayError> {
         Command::ComPinConfig(true, false).send(iface)