Buffer

[sbowman]

I love the library; perfect for helping parse a bit stream. But I'm having a problem with setting up the Reader.

I decode a Base64 string (a SCTE 35 signal) into a byte array and send it into iobit.NewReader(), but the binary that comes out doesn't look right.

If I parse through the byte array from the base64 string directly, bit by bit, I get a string of bits like this:

1111110001010101000000000101110100000001100100111101011101111100111111101111011000011101010110001011001001100000110000101000011100010011111111101111100111101111100011000000100110100110000101001100100000110000111001011100111110101011010100111010101010010101111110100100100010010111100001100011001101101001110001011001010100011010110101010101111010010110101001101110011110010010011001010111100010010000101101000100111011010111101100101001011001001111010110000111001110100001100111101010111010110011000100

But when I create a new reader from the decoded base64 string's byte array and loop through calling iobit.IsBit(), I get a string of bits like this:

11111100000000000101010100000000000000000000000000000000000000000000000000000000000000000000000000000101000001101000000001100100111101011101111100000000000000000011111100000010001111010100001101010101010001010100100101000001010000100100001101000100011111111101111100000000000000001111011100110001010000000000100100101001010000100100110001000001010000110100101101001111010101010101010000111010010101000101011101110100010010000100101100110000001100010100110101010011010001010100101001000110010110100101010101110100010110100100110100110011011001000100110001010111010001000100001001101000010011100110101101101100010100100110010001111010001100000011100100110100000000000000000001100111101010111010110011000100

When I try to parse the binary, I obviously get lots of 0 values that really shouldn't be 0.

Any idea what I'm doing wrong?

[bamiaux]

I wasn't able to reproduce your bug

func TestBug1(t *testing.T) {
    src := []byte{0xFC, 0x55, 0x00, 0x5D, 0x01, 0x93, 0xD7, 0x7C}
    r := NewReader(src[:])
    dst := make([]byte, len(src))
    w := NewWriter(dst[:])
    for i := 0; i < len(src)*8; i++ {
        v := uint32(0)
        if r.IsBit() {
            v = 1
        }
        w.PutUint32(1, v)
    }
    flushCheck(t, w)
    compare(t, src, dst)
}

In this test case, the first 8 bytes seems to be decoded fine, bit by bit, while you're suggesting they're not. Without any code, It'll be hard to say where the bug is.

[sbowman]

Maybe I'm doing something wrong. Something with the bytes produced by encoding/base64? I'll take a closer look at that.

I posted my test code as a Gist:

https://gist.github.com/sbowman/9512354

[bamiaux]

Your showBinary function is broken, you need to pad the printed value. Here's a modified version which give the same result manually and with iobit. I didn't check the whole string, but the first few bytes were correctly decoded

https://gist.github.com/bamiaux/9890754

[sbowman]

Damn. I'm an idiot. Sorry for that, and thanks for catching it. And thanks again for iobit.

On Mar 31, 2014, at 5:59 AM, Benoît Amiaux notifications@github.com wrote:

Your showBinary function is broken, you need to pad the printed value. Here's a modified version which give the same result manually and with iobit. I didn't check the whole string, but the first few bytes were correctly decoded

https://gist.github.com/bamiaux/9890754

— Reply to this email directly or view it on GitHub.

[bamiaux]

No worry, bugs can happen !