WIP - Implement abstractions for working with bytes

src/byte_buf.rs

@@ -0,0 +1,257 @@
+use {alloc, Bytes, SeqByteStr, BufResult, BufError, MAX_CAPACITY};
+use traits::{Buf, MutBuf, ByteStr};
+use std::{cmp, ptr};
+use std::num::UnsignedInt;
+
+/*
+ *
+ * ===== ByteBuf =====
+ *
+ */
+
+pub struct ByteBuf {
+    mem: alloc::MemRef,
+    cap: u32,
+    pos: u32,
+    lim: u32
+}
+
+impl ByteBuf {
+    pub fn from_slice(bytes: &[u8]) -> ByteBuf {
+        let mut buf = ByteBuf::mut_with_capacity(bytes.len());
+        buf.write(bytes).ok().expect("unexpected failure");
+        buf.flip()
+    }
+
+    pub fn mut_with_capacity(capacity: usize) -> MutByteBuf {
+        assert!(capacity <= MAX_CAPACITY);
+        MutByteBuf { buf: ByteBuf::new(capacity as u32) }
+    }
+
+    pub fn none() -> ByteBuf {
+        ByteBuf {
+            mem: alloc::MemRef::none(),
+            cap: 0,
+            pos: 0,
+            lim: 0,
+        }
+    }
+
+    pub unsafe fn from_mem_ref(mem: alloc::MemRef, cap: u32, pos: u32, lim: u32) -> ByteBuf {
+        debug_assert!(pos <= lim && lim <= cap, "invalid arguments; cap={}; pos={}; lim={}", cap, pos, lim);
+
+        ByteBuf {
+            mem: mem,
+            cap: cap,
+            pos: pos,
+            lim: lim,
+        }
+    }
+
+    fn new(mut capacity: u32) -> ByteBuf {
+        // Handle 0 capacity case
+        if capacity == 0 {
+            return ByteBuf::none();
+        }
+
+        // Round the capacity to the closest power of 2
+        capacity = UnsignedInt::next_power_of_two(capacity);
+
+        // Allocate the memory
+        let mem = alloc::HEAP.allocate(capacity as usize);
+
+        // If the allocation failed, return a blank buf
+        if mem.is_none() {
+            return ByteBuf::none();
+        }
+
+        ByteBuf {
+            mem: mem,
+            cap: capacity,
+            pos: 0,
+            lim: capacity
+        }
+    }
+
+    pub fn capacity(&self) -> usize {
+        self.cap as usize
+    }
+
+    pub fn flip(self) -> MutByteBuf {
+        let mut buf = MutByteBuf { buf: self };
+        buf.clear();
+        buf
+    }
+
+    pub fn read_slice(&mut self, dst: &mut [u8]) -> usize {
+        let len = cmp::min(dst.len(), self.remaining());
+        let cnt = len as u32;
+
+        unsafe {
+            ptr::copy_nonoverlapping_memory(
+                dst.as_mut_ptr(),
+                self.mem.ptr().offset(self.pos as isize), len);
+        }
+
+        self.pos += cnt;
+        len
+    }
+
+    pub fn to_seq_byte_str(self) -> SeqByteStr {
+        unsafe {
+            let ByteBuf { mem, pos, lim, .. } = self;
+            SeqByteStr::from_mem_ref(
+                mem, pos, lim - pos)
+        }
+    }
+
+    pub fn to_bytes(self) -> Bytes {
+        Bytes::of(self.to_seq_byte_str())
+    }
+
+    fn pos(&self) -> usize {
+        self.pos as usize
+    }
+
+    fn lim(&self) -> usize {
+        self.lim as usize
+    }
+
+    fn remaining_u32(&self) -> u32 {
+        self.lim - self.pos
+    }
+
+    fn ensure_remaining(&self, cnt: usize) -> BufResult<()> {
+        if cnt > self.remaining() {
+            return Err(BufError::Overflow);
+        }
+
+        Ok(())
+    }
+}
+
+impl Buf for ByteBuf {
+    fn remaining(&self) -> usize {
+        self.remaining_u32() as usize
+    }
+
+    fn bytes<'a>(&'a self) -> &'a [u8] {
+        &self.mem.bytes()[self.pos()..self.lim()]
+    }
+
+    fn advance(&mut self, mut cnt: usize) {
+        cnt = cmp::min(cnt, self.remaining());
+        self.pos += cnt as u32;
+    }
+
+    fn read_slice(&mut self, dst: &mut [u8]) -> usize {
+        ByteBuf::read_slice(self, dst)
+    }
+}
+
+unsafe impl Send for ByteBuf { }
+
+/*
+ *
+ * ===== ROByteBuf =====
+ *
+ */
+
+/// Same as `ByteBuf` but cannot be flipped to a `MutByteBuf`.
+pub struct ROByteBuf {
+    buf: ByteBuf,
+}
+
+impl ROByteBuf {
+    pub unsafe fn from_mem_ref(mem: alloc::MemRef, cap: u32, pos: u32, lim: u32) -> ROByteBuf {
+        ROByteBuf {
+            buf: ByteBuf::from_mem_ref(mem, cap, pos, lim)
+        }
+    }
+
+    pub fn to_seq_byte_str(self) -> SeqByteStr {
+        self.buf.to_seq_byte_str()
+    }
+
+    pub fn to_bytes(self) -> Bytes {
+        self.buf.to_bytes()
+    }
+}
+
+impl Buf for ROByteBuf {
+
+    fn remaining(&self) -> usize {
+        self.buf.remaining()
+    }
+
+    fn bytes<'a>(&'a self) -> &'a [u8] {
+        self.buf.bytes()
+    }
+
+    fn advance(&mut self, cnt: usize) {
+        self.buf.advance(cnt)
+    }
+
+    fn read_slice(&mut self, dst: &mut [u8]) -> usize {
+        self.buf.read_slice(dst)
+    }
+}
+
+/*
+ *
+ * ===== MutByteBuf =====
+ *
+ */
+
+pub struct MutByteBuf {
+    buf: ByteBuf,
+}
+
+impl MutByteBuf {
+    pub fn capacity(&self) -> usize {
+        self.buf.capacity() as usize
+    }
+
+    pub fn flip(self) -> ByteBuf {
+        let mut buf = self.buf;
+
+        buf.lim = buf.pos;
+        buf.pos = 0;
+        buf
+    }
+
+    pub fn clear(&mut self) {
+        self.buf.pos = 0;
+        self.buf.lim = self.buf.cap;
+    }
+
+    pub fn write_slice(&mut self, src: &[u8]) -> BufResult<()> {
+        try!(self.buf.ensure_remaining(src.len()));
+        let cnt = src.len() as u32;
+
+        unsafe {
+            ptr::copy_nonoverlapping_memory(
+                self.buf.mem.ptr().offset(self.buf.pos as isize),
+                src.as_ptr(), src.len());
+        }
+
+        self.buf.pos += cnt;
+        return Ok(());
+    }
+}
+
+impl MutBuf for MutByteBuf {
+    fn remaining(&self) -> usize {
+        self.buf.remaining()
+    }
+
+    fn advance(&mut self, cnt: usize) {
+        self.buf.advance(cnt)
+    }
+
+    fn mut_bytes<'a>(&'a mut self) -> &'a mut [u8] {
+        let pos = self.buf.pos();
+        let lim = self.buf.lim();
+        &mut self.buf.mem.bytes_mut()[pos..lim]
+    }
+}