Bug

[andreis]

	in := "1111111111"
	fmt.Println("in: ", in)
	v, err := base58.Decode(in)
	fmt.Println("decode:", v, err)

	fmt.Println("encode again:", base58.Encode(v))

Try this with your function names instead (by the way, I suggest you get rid of Trivial* and rename the fast versions to Encode and Decode). Output should look like this:

in:  1111111111
decode: [0 0 0] <nil>
encode again: 111

[mr-tron]

Thanks for bug report.
This is problem in FastDecoding implementation, which was written by @njones. Excuse me that I merged without good testing.
I made functions Encode and Decode which call fast version for encoding and trivilal for decoding (as fast workaround).
I will fix fast decoding implementation tomorrow.

[andreis]

No worries Denis, I switched to btcutil until you sort this one out, I would love to use your much faster code. (after all we use base58 for tokens so it's definitely a hot path for us)

I think you can adapt these simple tests very easily https://github.com/btcsuite/btcutil/blob/master/base58/base58_test.go

[mr-tron]

fixed 44792f7