Release v0.1.0

vendor/github.com/btcsuite/btcutil/base58/base58.go

@@ -0,0 +1,75 @@
+// Copyright (c) 2013-2015 The btcsuite developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package base58
+
+import (
+	"math/big"
+)
+
+//go:generate go run genalphabet.go
+
+var bigRadix = big.NewInt(58)
+var bigZero = big.NewInt(0)
+
+// Decode decodes a modified base58 string to a byte slice.
+func Decode(b string) []byte {
+	answer := big.NewInt(0)
+	j := big.NewInt(1)
+
+	scratch := new(big.Int)
+	for i := len(b) - 1; i >= 0; i-- {
+		tmp := b58[b[i]]
+		if tmp == 255 {
+			return []byte("")
+		}
+		scratch.SetInt64(int64(tmp))
+		scratch.Mul(j, scratch)
+		answer.Add(answer, scratch)
+		j.Mul(j, bigRadix)
+	}
+
+	tmpval := answer.Bytes()
+
+	var numZeros int
+	for numZeros = 0; numZeros < len(b); numZeros++ {
+		if b[numZeros] != alphabetIdx0 {
+			break
+		}
+	}
+	flen := numZeros + len(tmpval)
+	val := make([]byte, flen)
+	copy(val[numZeros:], tmpval)
+
+	return val
+}
+
+// Encode encodes a byte slice to a modified base58 string.
+func Encode(b []byte) string {
+	x := new(big.Int)
+	x.SetBytes(b)
+
+	answer := make([]byte, 0, len(b)*136/100)
+	for x.Cmp(bigZero) > 0 {
+		mod := new(big.Int)
+		x.DivMod(x, bigRadix, mod)
+		answer = append(answer, alphabet[mod.Int64()])
+	}
+
+	// leading zero bytes
+	for _, i := range b {
+		if i != 0 {
+			break
+		}
+		answer = append(answer, alphabetIdx0)
+	}
+
+	// reverse
+	alen := len(answer)
+	for i := 0; i < alen/2; i++ {
+		answer[i], answer[alen-1-i] = answer[alen-1-i], answer[i]
+	}
+
+	return string(answer)
+}