add to_owned

src/endianness.rs

@@ -13,6 +13,8 @@ pub trait Endianness: private::Sealed {
     fn is_le() -> bool;
     /// Input is big endian
     fn is_be() -> bool;
+    /// Get an instance of the endianness
+    fn endianness() -> Self;
 }
 
 /// Marks the buffer or stream as big endian
@@ -24,7 +26,7 @@ pub struct BigEndian;
 pub struct LittleEndian;
 
 macro_rules! impl_endianness {
-    ($type:ty, $le:expr) => {
+    ($type:ty, $le:expr, $instance:expr) => {
         impl Endianness for $type {
             #[inline(always)]
             fn is_le() -> bool {
@@ -35,12 +37,16 @@ macro_rules! impl_endianness {
             fn is_be() -> bool {
                 !$le
             }
+
+            fn endianness() -> Self {
+                $instance
+            }
         }
     };
 }
 
-impl_endianness!(BigEndian, false);
-impl_endianness!(LittleEndian, true);
+impl_endianness!(BigEndian, false, BigEndian);
+impl_endianness!(LittleEndian, true, LittleEndian);
 
 mod private {
     pub trait Sealed {}

src/readbuffer.rs

@@ -18,7 +18,7 @@ const USIZE_SIZE: usize = size_of::<usize>();
 const USIZE_BIT_SIZE: usize = USIZE_SIZE * 8;
 
 // Cow<[u8]> but with cheap clones using Rc
-enum Data<'a> {
+pub(crate) enum Data<'a> {
     Borrowed(&'a [u8]),
     Owned(Rc<[u8]>),
 }
@@ -34,6 +34,14 @@ impl<'a> Data<'a> {
     pub fn len(&self) -> usize {
         self.as_slice().len()
     }
+
+    pub fn to_owned(&self) -> Data<'static> {
+        let bytes = match self {
+            Data::Borrowed(bytes) => Rc::from(bytes.to_vec()),
+            Data::Owned(bytes) => Rc::clone(bytes),
+        };
+        Data::Owned(bytes.into())
+    }
 }
 
 impl<'a> Index<Range<usize>> for Data<'a> {
@@ -92,7 +100,7 @@ pub struct BitReadBuffer<'a, E>
 where
     E: Endianness,
 {
-    bytes: Data<'a>,
+    pub(crate) bytes: Data<'a>,
     bit_len: usize,
     endianness: PhantomData<E>,
     slice: &'a [u8],
@@ -125,6 +133,27 @@ where
             slice: bytes,
         }
     }
+
+    /// Create a static version of this buffer
+    ///
+    /// If the current buffer is borrowed, this will copy the data
+    pub fn to_owned(&self) -> BitReadBuffer<'static, E> {
+        let bytes = self.bytes.to_owned();
+        let byte_len = bytes.len();
+
+        // this is safe because
+        //  - the slice can only be access trough this struct
+        //  - this struct keeps the vec the slice comes from alive
+        //  - this struct doesn't allow mutation
+        let slice = unsafe { std::slice::from_raw_parts(bytes.as_slice().as_ptr(), bytes.len()) };
+
+        BitReadBuffer {
+            bytes,
+            bit_len: byte_len * 8,
+            endianness: PhantomData,
+            slice,
+        }
+    }
 }
 
 impl<E> BitReadBuffer<'static, E>
@@ -190,7 +219,7 @@ where
 
     /// The available number of bytes in the buffer
     pub fn byte_len(&self) -> usize {
-        self.bytes.len()
+        self.slice.len()
     }
 
     unsafe fn read_usize_bytes(&self, byte_index: usize, end: bool) -> [u8; USIZE_SIZE] {
@@ -710,28 +739,13 @@ where
 
 impl<'a, E: Endianness> From<&'a [u8]> for BitReadBuffer<'a, E> {
     fn from(bytes: &'a [u8]) -> Self {
-        let byte_len = bytes.len();
-        BitReadBuffer {
-            bytes: Data::Borrowed(bytes),
-            bit_len: byte_len * 8,
-            endianness: PhantomData,
-            slice: bytes,
-        }
+        BitReadBuffer::new(bytes, E::endianness())
     }
 }
 
 impl<'a, E: Endianness> From<Vec<u8>> for BitReadBuffer<'a, E> {
     fn from(bytes: Vec<u8>) -> Self {
-        let byte_len = bytes.len();
-        let bytes = Data::Owned(Rc::from(bytes));
-        let slice = unsafe { std::slice::from_raw_parts(bytes.as_slice().as_ptr(), bytes.len()) };
-
-        BitReadBuffer {
-            bytes,
-            bit_len: byte_len * 8,
-            endianness: PhantomData,
-            slice,
-        }
+        BitReadBuffer::new_owned(bytes, E::endianness())
     }
 }
 

src/readstream.rs

@@ -5,6 +5,7 @@ use num_traits::{Float, PrimInt};
 
 use crate::endianness::Endianness;
 use crate::num_traits::{IsSigned, UncheckedPrimitiveFloat, UncheckedPrimitiveInt};
+use crate::readbuffer::Data;
 use crate::BitReadBuffer;
 use crate::{BitError, BitRead, BitReadSized, Result};
 use std::borrow::Cow;
@@ -660,6 +661,37 @@ where
             Ok(false)
         }
     }
+
+    /// Create an owned copy of this stream
+    pub fn to_owned(&self) -> BitReadStream<'static, E> {
+        match self.buffer.bytes {
+            Data::Owned(_) => BitReadStream {
+                // already owned, so buffer.to_owned is a cheap rc clone
+                buffer: self.buffer.to_owned(),
+                start_pos: self.pos,
+                pos: self.pos,
+            },
+            Data::Borrowed(bytes) => {
+                // instead of calling buffer.to_owned blindly, we only copy the bytes that this stream covers
+                let byte_pos = self.start_pos / 8;
+                let bit_offset = self.start_pos & 7;
+
+                let end = self.buffer.bit_len() / 8 + 1;
+                let end = min(end, self.buffer.byte_len());
+
+                let sub_bytes = bytes[byte_pos..end].to_vec();
+                let buffer = BitReadBuffer::from(sub_bytes)
+                    .get_sub_buffer(self.buffer.bit_len() - self.start_pos + bit_offset)
+                    .unwrap();
+
+                BitReadStream {
+                    buffer,
+                    start_pos: bit_offset,
+                    pos: bit_offset + (self.pos - self.start_pos),
+                }
+            }
+        }
+    }
 }
 
 impl<'a, E: Endianness> Clone for BitReadStream<'a, E> {