LfnBuffer now borrows its contents.

Removes a bunch of const generics from the API.

Author: thejpster

examples/shell.rs

@@ -231,7 +231,8 @@ impl Context {
     fn dir(&self, path: &Path) -> Result<(), Error> {
         println!("Directory listing of {:?}", path);
         let dir = self.resolve_existing_directory(path)?;
-        let mut lfn_buffer = LfnBuffer::<256>::new();
+        let mut storage = [0u8; 128];
+        let mut lfn_buffer = LfnBuffer::new(&mut storage);
         dir.iterate_dir_lfn(&mut lfn_buffer, |entry, lfn| {
             if !entry.attributes.is_volume() {
                 print!(

src/fat/volume.rs

@@ -540,10 +540,10 @@ impl FatVolume {
     /// including the Long File Name.
     ///
     /// Useful for performing directory listings.
-    pub(crate) fn iterate_dir_lfn<D, F, const N: usize>(
+    pub(crate) fn iterate_dir_lfn<D, F>(
         &self,
         block_cache: &mut BlockCache<D>,
-        lfn_buffer: &mut LfnBuffer<N>,
+        lfn_buffer: &mut LfnBuffer<'_>,
         dir_info: &DirectoryInfo,
         mut func: F,
     ) -> Result<(), Error<D::Error>>
@@ -559,9 +559,9 @@ impl FatVolume {
         }
 
         impl SeqState {
-            fn update<const N: usize>(
+            fn update(
                 self,
-                lfn_buffer: &mut LfnBuffer<N>,
+                lfn_buffer: &mut LfnBuffer<'_>,
                 start: bool,
                 sequence: u8,
                 csum: u8,

src/filesystem/directory.rs

@@ -176,9 +176,9 @@ where
     /// object is already locked in order to do the iteration.
     ///
     /// </div>
-    pub fn iterate_dir_lfn<F, const N: usize>(
+    pub fn iterate_dir_lfn<F>(
         &self,
-        lfn_buffer: &mut LfnBuffer<N>,
+        lfn_buffer: &mut LfnBuffer<'_>,
         func: F,
     ) -> Result<(), Error<D::Error>>
     where

src/filesystem/filename.rs

@@ -221,11 +221,9 @@ impl core::fmt::Debug for ShortFileName {
 }
 
 /// Used to store a Long File Name
-///
-/// The const generic specifies the maximum capacity in bytes.
-pub struct LfnBuffer<const N: usize> {
+pub struct LfnBuffer<'a> {
     /// We fill this buffer in from the back
-    inner: [u8; N],
+    inner: &'a mut [u8],
     /// How many bytes are free.
     ///
     /// This is also the byte index the string starts from.
@@ -234,19 +232,20 @@ pub struct LfnBuffer<const N: usize> {
     overflow: bool,
 }
 
-impl<const N: usize> LfnBuffer<N> {
-    /// Create a new, empty, LFN Buffer
-    pub fn new() -> LfnBuffer<N> {
+impl<'a> LfnBuffer<'a> {
+    /// Create a new, empty, LFN Buffer using the given mutable slice as its storage.
+    pub fn new(storage: &'a mut [u8]) -> LfnBuffer<'a> {
+        let len = storage.len();
         LfnBuffer {
-            inner: [0u8; N],
-            free: N,
+            inner: storage,
+            free: len,
             overflow: false,
         }
     }
 
     /// Empty out this buffer
     pub fn clear(&mut self) {
-        self.free = N;
+        self.free = self.inner.len();
         self.overflow = false;
     }
 
@@ -291,12 +290,6 @@ impl<const N: usize> LfnBuffer<N> {
     }
 }
 
-impl<const N: usize> core::default::Default for LfnBuffer<N> {
-    fn default() -> Self {
-        LfnBuffer::new()
-    }
-}
-
 // ****************************************************************************
 //
 // Unit Tests
@@ -402,7 +395,8 @@ mod test {
 
     #[test]
     fn one_piece() {
-        let mut buf: LfnBuffer<64> = LfnBuffer::new();
+        let mut storage = [0u8; 64];
+        let mut buf: LfnBuffer = LfnBuffer::new(&mut storage);
         buf.push(&[
             0x0030, 0x0031, 0x0032, 0x0033, 0x2202, 0x0000, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
             0xFFFF, 0xFFFF,
@@ -412,7 +406,8 @@ mod test {
 
     #[test]
     fn two_piece() {
-        let mut buf: LfnBuffer<64> = LfnBuffer::new();
+        let mut storage = [0u8; 64];
+        let mut buf: LfnBuffer = LfnBuffer::new(&mut storage);
         buf.push(&[
             0x0030, 0x0031, 0x0032, 0x0033, 0x2202, 0x0000, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
             0xFFFF, 0xFFFF,

src/volume_mgr.rs

@@ -435,10 +435,10 @@ where
     /// object is already locked in order to do the iteration.
     ///
     /// </div>
-    pub fn iterate_dir_lfn<F, const N: usize>(
+    pub fn iterate_dir_lfn<F>(
         &self,
         directory: RawDirectory,
-        lfn_buffer: &mut LfnBuffer<N>,
+        lfn_buffer: &mut LfnBuffer<'_>,
         func: F,
     ) -> Result<(), Error<D::Error>>
     where

tests/directories.rs

@@ -101,7 +101,8 @@ fn fat16_root_directory_listing() {
     ];
 
     let mut listing = Vec::new();
-    let mut lfn_buffer: LfnBuffer<128> = LfnBuffer::new();
+    let mut storage = [0u8; 128];
+    let mut lfn_buffer: LfnBuffer = LfnBuffer::new(&mut storage);
 
     volume_mgr
         .iterate_dir_lfn(root_dir, &mut lfn_buffer, |d, opt_lfn| {
@@ -288,7 +289,8 @@ fn fat32_root_directory_listing() {
     ];
 
     let mut listing = Vec::new();
-    let mut lfn_buffer: LfnBuffer<128> = LfnBuffer::new();
+    let mut storage = [0u8; 128];
+    let mut lfn_buffer: LfnBuffer = LfnBuffer::new(&mut storage);
 
     volume_mgr
         .iterate_dir_lfn(root_dir, &mut lfn_buffer, |d, opt_lfn| {