codec/h264/h264dec: added binToInt function and test

This function will convert binary provided as a string and return as int.

codec/h264/h264dec/helpers.go

@@ -9,6 +9,7 @@ package h264dec
 
 import (
 	"errors"
+	"math"
 )
 
 // binToSlice is a helper function to convert a string of binary into a
@@ -42,6 +43,21 @@ func binToSlice(s string) ([]byte, error) {
 	return bytes, nil
 }
 
+// binToInt converts a binary string provided as a string and returns as an int.
+// White spaces are ignored.
+func binToInt(s string) (int, error) {
+	var sum int
+	var nSpace int
+	for i := len(s) - 1; i >= 0; i-- {
+		if s[i] == ' ' {
+			nSpace++
+			continue
+		}
+		sum += int(math.Pow(2, float64(len(s)-1-i-nSpace))) * int(s[i]-'0')
+	}
+	return sum, nil
+}
+
 func maxi(a, b int) int {
 	if a > b {
 		return a

codec/h264/h264dec/helpers_test.go

@@ -0,0 +1,28 @@
+package h264dec
+
+import "testing"
+
+func TestBinToInt(t *testing.T) {
+	tests := []struct {
+		in   string
+		want int
+	}{
+		{in: "101", want: 5},
+		{in: "1", want: 1},
+		{in: "00000", want: 0},
+		{in: "", want: 0},
+		{in: "1111", want: 15},
+		{in: "1 111", want: 15},
+	}
+
+	for i, test := range tests {
+		n, err := binToInt(test.in)
+		if err != nil {
+			t.Errorf("did not expect error: %v from binToInt", err)
+		}
+
+		if n != test.want {
+			t.Errorf("did not get expected result for test %d\nGot: %v\nWant: %v\n", i, n, test.want)
+		}
+	}
+}