From de6bbef97fce344102e713f60b327ab6ad33c172 Mon Sep 17 00:00:00 2001
From: Alex Yatskov <alex@foosoft.net>
Date: Sun, 13 Jan 2019 19:02:49 -0800
Subject: [PATCH] work on bitreader

---
 streaming/bitreader.go      | 47 +++++++++++++++++++++++++++++++++++++
 streaming/streaming_test.go |  7 ++++++
 2 files changed, 54 insertions(+)
 create mode 100644 streaming/bitreader.go
 create mode 100644 streaming/streaming_test.go

diff --git a/streaming/bitreader.go b/streaming/bitreader.go
new file mode 100644
index 0000000..4ea80a2
--- /dev/null
+++ b/streaming/bitreader.go
@@ -0,0 +1,47 @@
+package streaming
+
+import (
+	"errors"
+	"io"
+)
+
+type BitReader struct {
+	reader io.Reader
+	offset int
+	buffer [1]byte
+}
+
+func New(reader io.Reader) *BitReader {
+	return &BitReader{reader: reader}
+}
+
+func (r *BitReader) ReadBits(count int) (uint64, error) {
+	if count > 64 {
+		return 0, errors.New("cannot read more than 64 bits at a time")
+	}
+
+	var value uint64
+	for count > 0 {
+		bitOffset := r.offset % 8
+		bitsLeft := 8 - bitOffset
+		if bitsLeft == 8 {
+			if _, err := r.reader.Read(r.buffer[:]); err != nil {
+				return 0, err
+			}
+		}
+
+		bitsRead := count
+		if bitsRead > bitsLeft {
+			bitsRead = bitsLeft
+		}
+
+		buffer := r.buffer[0]
+		buffer <<= uint(bitOffset)
+		buffer >>= (uint(bitOffset) + uint(bitsLeft-bitsRead))
+
+		value <<= uint(bitsRead)
+		value |= uint64(buffer)
+	}
+
+	return value, nil
+}
diff --git a/streaming/streaming_test.go b/streaming/streaming_test.go
new file mode 100644
index 0000000..9c23bce
--- /dev/null
+++ b/streaming/streaming_test.go
@@ -0,0 +1,7 @@
+package streaming
+
+import "testing"
+
+func TestBitReader(t *testing.T) {
+
+}