From a08480e8cd5df93a953323b400914520d5963660 Mon Sep 17 00:00:00 2001
From: BiSaXa <1669855+BiSaXa@users.noreply.github.com>
Date: Sun, 4 Sep 2022 14:53:07 +0300
Subject: added skipbytes, 64 bit support for readbits, new readme

---
 README.md         | 37 +++++++++++++++++++++++++++++++++++++
 bitreader.go      | 26 +++++++++++++++++++-------
 bitreader_test.go | 13 ++++++++-----
 3 files changed, 64 insertions(+), 12 deletions(-)

diff --git a/README.md b/README.md
index a493a1f..4f28e7b 100644
--- a/README.md
+++ b/README.md
@@ -1 +1,38 @@
 # BitReader
+A simple bit reader with big/little-endian support for golang.\
+Reads data from an existing byte array.\
+Uses string manipulation (for now).\
+Support reading up to 64 bits at one time.\
+Checking for overflowing the data.
+
+## Installation
+```bash
+$ go get github.com/bisaxa/bitreader
+```
+
+## Usage
+
+```go
+import "github.com/bisaxa/bitreader"
+
+// data: []byte  Data to read from byte array
+// le:     bool  Little-endian(true) or big-endian(false) state
+reader := bitreader.Reader(data, le)
+
+// read first bit
+state, err := reader.ReadBit()
+
+// skip bits/bytes
+err := reader.SkipBits(8)
+err := reader.SkipBytes(4)
+
+// read bits
+value, err := reader.ReadBits(11)
+value, err := reader.ReadBits(64) // up to 64 bits
+```
+
+## Error Handling
+ReadBits(x), ReadBit(), SkipBits(x) and SkipBytes(x) functions returns an error message when they don't work as expected. It is advised to always handle errors.
+
+## License
+This project is licensed under [MIT License](LICENSE).
\ No newline at end of file
diff --git a/bitreader.go b/bitreader.go
index b105df7..635776b 100644
--- a/bitreader.go
+++ b/bitreader.go
@@ -33,6 +33,10 @@ func (reader *ReaderType) SkipBits(bits int) error {
 	if bits <= 0 {
 		return fmt.Errorf("SkipBits Error: Bits value %d lower or equals than 0.", bits)
 	}
+	err := reader.checkAvailableBits(bits)
+	if err != nil {
+		return err
+	}
 	for reader.index+bits > 7 {
 		reader.base++
 		reader.index = 0
@@ -42,12 +46,20 @@ func (reader *ReaderType) SkipBits(bits int) error {
 	return nil
 }
 
-func (reader *ReaderType) ReadBits32(bits int) (int, error) {
+func (reader *ReaderType) SkipBytes(bytes int) error {
+	err := reader.SkipBits(bytes * 8)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (reader *ReaderType) ReadBits(bits int) (int, error) {
 	if bits <= 0 {
 		return -1, fmt.Errorf("ReadBits Error: Bits value %d lower or equals than 0.", bits)
 	}
-	if bits > 32 {
-		return -1, fmt.Errorf("ReadBits Error: Bits value %d higher than 32.", bits)
+	if bits > 64 {
+		return -1, fmt.Errorf("ReadBits Error: Bits value %d higher than 64.", bits)
 	}
 	err := reader.checkAvailableBits(bits)
 	if err != nil {
@@ -79,7 +91,7 @@ func (reader *ReaderType) ReadBits32(bits int) (int, error) {
 			reader.index -= 8
 		}
 		// Conversion of string binary to int
-		value, err := strconv.ParseUint(output, 2, 32)
+		value, err := strconv.ParseUint(output, 2, 64)
 		if err != nil {
 			return -1, fmt.Errorf("%s", err)
 		}
@@ -97,7 +109,7 @@ func (reader *ReaderType) ReadBits32(bits int) (int, error) {
 			}
 		}
 		// Conversion of string binary to int
-		value, err := strconv.ParseUint(output, 2, 32)
+		value, err := strconv.ParseUint(output, 2, 64)
 		if err != nil {
 			return -1, fmt.Errorf("%s", err)
 		}
@@ -106,7 +118,7 @@ func (reader *ReaderType) ReadBits32(bits int) (int, error) {
 }
 
 func (reader *ReaderType) ReadBit() (bool, error) {
-	value, err := reader.ReadBits32(1)
+	value, err := reader.ReadBits(1)
 	if err != nil {
 		return false, fmt.Errorf("ReadBit Error: %s", err)
 	}
@@ -116,7 +128,7 @@ func (reader *ReaderType) ReadBit() (bool, error) {
 func (reader *ReaderType) checkAvailableBits(bits int) error {
 	availableBits := (len(reader.data)-reader.base)*8 - reader.index
 	if availableBits < bits {
-		return fmt.Errorf("BitReaderOutOfBounds: Wanted to read %d bit(s) but only %d bit(s) is/are available.", bits, availableBits)
+		return fmt.Errorf("BitReaderOutOfBounds: Wanted to read/skip %d bit(s) but only %d bit(s) is/are available.", bits, availableBits)
 	}
 	return nil
 }
diff --git a/bitreader_test.go b/bitreader_test.go
index aed0930..ef421a8 100644
--- a/bitreader_test.go
+++ b/bitreader_test.go
@@ -47,7 +47,7 @@ func TestReadBits32(t *testing.T) {
 		if err != nil {
 			t.Fatal(err)
 		}
-		value, err := bitreader.ReadBits32(32)
+		value, err := bitreader.ReadBits(32)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -57,12 +57,12 @@ func TestReadBits32(t *testing.T) {
 	}
 }
 
-func TestReadBits32LSB(t *testing.T) {
+func TestReadBitsLE(t *testing.T) {
 	bitreader := Reader(TestArray[:], true)
 	expected := []int{1720, 1768} // 11010111000, 11011101000
 	for i := range expected {
 		bitreader.ReadBit()
-		value, err := bitreader.ReadBits32(32)
+		value, err := bitreader.ReadBits(32)
 		if err != nil {
 			t.Fatal(err)
 		}
@@ -75,7 +75,10 @@ func TestReadBits32LSB(t *testing.T) {
 func TestSkipBits(t *testing.T) {
 	bitreader := Reader(TestArray[:], false)
 	expected := []bool{true, true, false, true} //00001101
-	bitreader.SkipBits(12)
+	err := bitreader.SkipBits(12)
+	if err != nil {
+		t.Fatal(err)
+	}
 	for i := range expected {
 		value, err := bitreader.ReadBit()
 		if err != nil {
@@ -87,7 +90,7 @@ func TestSkipBits(t *testing.T) {
 	}
 }
 
-func TestSkipBitsLSB(t *testing.T) {
+func TestSkipBitsLE(t *testing.T) {
 	bitreader := Reader(TestArray[:], true)
 	expected := []bool{false, false, false, false} //10110000
 	bitreader.SkipBits(12)
-- 
cgit v1.2.3