inline count check

benches/bench.rs

@@ -2,9 +2,8 @@
 
 extern crate test;
 
-use std::fs;
-use test::Bencher;
 use bitstream_reader::{BitBuffer, LittleEndian};
+use test::Bencher;
 
 fn read_perf(buffer: &BitBuffer<LittleEndian>) -> u16 {
     let size = 5;
@@ -23,11 +22,11 @@ fn read_perf(buffer: &BitBuffer<LittleEndian>) -> u16 {
 
 #[bench]
 fn perf_non_padded(b: &mut Bencher) {
-    let file = fs::read("/bulk/tmp/test.dem").expect("Unable to read file");
-    let buffer = BitBuffer::new(file, LittleEndian);
+    let data = vec![1u8; 1024 * 1024 * 10];
+    let buffer = BitBuffer::new(data, LittleEndian);
     b.iter(|| {
         let data = read_perf(&buffer);
-        assert_eq!(data, 43943);
+        assert_eq!(data, 0);
         test::black_box(data);
     });
 }

src/buffer.rs

@@ -176,20 +176,32 @@ where
     ///
     /// [`ReadError::NotEnoughData`]: enum.ReadError.html#variant.NotEnoughData
     /// [`ReadError::TooManyBits`]: enum.ReadError.html#variant.TooManyBits
+    #[inline]
     pub fn read_int<T>(&self, position: usize, count: usize) -> Result<T>
     where
         T: PrimInt + BitOrAssign + IsSigned + UncheckedPrimitiveInt,
     {
-        let value = {
         let type_bit_size = size_of::<T>() * 8;
-            let usize_bit_size = size_of::<usize>() * 8;
 
+        // by splitting of the count check and the actual reading
+        // we can inline the count check (which get's resolved at compile time if a constant count is used)
+        // without having to pay the potentional cost of inlining a larger function
         if type_bit_size < count {
             return Err(ReadError::TooManyBits {
                 requested: count,
                 max: type_bit_size,
             });
         }
+        self.read_int_no_count_check(position, count)
+    }
+
+    fn read_int_no_count_check<T>(&self, position: usize, count: usize) -> Result<T>
+    where
+        T: PrimInt + BitOrAssign + IsSigned + UncheckedPrimitiveInt,
+    {
+        let value = {
+            let type_bit_size = size_of::<T>() * 8;
+            let usize_bit_size = size_of::<usize>() * 8;
 
             if position + count > self.bit_len {
                 if position > self.bit_len {