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// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
 
// Package base32 implements base32 encoding as specified by RFC 4648.
package base32
 
import (
        "io"
        "strconv"
)
 
/*
 * Encodings
 */
 
// An Encoding is a radix 32 encoding/decoding scheme, defined by a
// 32-character alphabet.  The most common is the "base32" encoding
// introduced for SASL GSSAPI and standardized in RFC 4648.
// The alternate "base32hex" encoding is used in DNSSEC.
type Encoding struct {
        encode    string
        decodeMap [256]byte
}
 
const encodeStd = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"
const encodeHex = "0123456789ABCDEFGHIJKLMNOPQRSTUV"
 
// NewEncoding returns a new Encoding defined by the given alphabet,
// which must be a 32-byte string.
func NewEncoding(encoder string) *Encoding {
        e := new(Encoding)
        e.encode = encoder
        for i := 0; i < len(e.decodeMap); i++ {
                e.decodeMap[i] = 0xFF
        }
        for i := 0; i < len(encoder); i++ {
                e.decodeMap[encoder[i]] = byte(i)
        }
        return e
}
 
// StdEncoding is the standard base32 encoding, as defined in
// RFC 4648.
var StdEncoding = NewEncoding(encodeStd)
 
// HexEncoding is the ``Extended Hex Alphabet'' defined in RFC 4648.
// It is typically used in DNS.
var HexEncoding = NewEncoding(encodeHex)
 
/*
 * Encoder
 */
 
// Encode encodes src using the encoding enc, writing
// EncodedLen(len(src)) bytes to dst.
//
// The encoding pads the output to a multiple of 8 bytes,
// so Encode is not appropriate for use on individual blocks
// of a large data stream.  Use NewEncoder() instead.
func (enc *Encoding) Encode(dst, src []byte) {
        if len(src) == 0 {
                return
        }
 
        for len(src) > 0 {
                dst[0] = 0
                dst[1] = 0
                dst[2] = 0
                dst[3] = 0
                dst[4] = 0
                dst[5] = 0
                dst[6] = 0
                dst[7] = 0
 
                // Unpack 8x 5-bit source blocks into a 5 byte
                // destination quantum
                switch len(src) {
                default:
                        dst[7] |= src[4] & 0x1F
                        dst[6] |= src[4] >> 5
                        fallthrough
                case 4:
                        dst[6] |= (src[3] << 3) & 0x1F
                        dst[5] |= (src[3] >> 2) & 0x1F
                        dst[4] |= src[3] >> 7
                        fallthrough
                case 3:
                        dst[4] |= (src[2] << 1) & 0x1F
                        dst[3] |= (src[2] >> 4) & 0x1F
                        fallthrough
                case 2:
                        dst[3] |= (src[1] << 4) & 0x1F
                        dst[2] |= (src[1] >> 1) & 0x1F
                        dst[1] |= (src[1] >> 6) & 0x1F
                        fallthrough
                case 1:
                        dst[1] |= (src[0] << 2) & 0x1F
                        dst[0] |= src[0] >> 3
                }
 
                // Encode 5-bit blocks using the base32 alphabet
                for j := 0; j < 8; j++ {
                        dst[j] = enc.encode[dst[j]]
                }
 
                // Pad the final quantum
                if len(src) < 5 {
                        dst[7] = '='
                        if len(src) < 4 {
                                dst[6] = '='
                                dst[5] = '='
                                if len(src) < 3 {
                                        dst[4] = '='
                                        if len(src) < 2 {
                                                dst[3] = '='
                                                dst[2] = '='
                                        }
                                }
                        }
                        break
                }
                src = src[5:]
                dst = dst[8:]
        }
}
 
// EncodeToString returns the base32 encoding of src.
func (enc *Encoding) EncodeToString(src []byte) string {
        buf := make([]byte, enc.EncodedLen(len(src)))
        enc.Encode(buf, src)
        return string(buf)
}
 
type encoder struct {
        err  error
        enc  *Encoding
        w    io.Writer
        buf  [5]byte    // buffered data waiting to be encoded
        nbuf int        // number of bytes in buf
        out  [1024]byte // output buffer
}
 
func (e *encoder) Write(p []byte) (n int, err error) {
        if e.err != nil {
                return 0, e.err
        }
 
        // Leading fringe.
        if e.nbuf > 0 {
                var i int
                for i = 0; i < len(p) && e.nbuf < 5; i++ {
                        e.buf[e.nbuf] = p[i]
                        e.nbuf++
                }
                n += i
                p = p[i:]
                if e.nbuf < 5 {
                        return
                }
                e.enc.Encode(e.out[0:], e.buf[0:])
                if _, e.err = e.w.Write(e.out[0:8]); e.err != nil {
                        return n, e.err
                }
                e.nbuf = 0
        }
 
        // Large interior chunks.
        for len(p) >= 5 {
                nn := len(e.out) / 8 * 5
                if nn > len(p) {
                        nn = len(p)
                }
                nn -= nn % 5
                if nn > 0 {
                        e.enc.Encode(e.out[0:], p[0:nn])
                        if _, e.err = e.w.Write(e.out[0 : nn/5*8]); e.err != nil {
                                return n, e.err
                        }
                }
                n += nn
                p = p[nn:]
        }
 
        // Trailing fringe.
        for i := 0; i < len(p); i++ {
                e.buf[i] = p[i]
        }
        e.nbuf = len(p)
        n += len(p)
        return
}
 
// Close flushes any pending output from the encoder.
// It is an error to call Write after calling Close.
func (e *encoder) Close() error {
        // If there's anything left in the buffer, flush it out
        if e.err == nil && e.nbuf > 0 {
                e.enc.Encode(e.out[0:], e.buf[0:e.nbuf])
                e.nbuf = 0
                _, e.err = e.w.Write(e.out[0:8])
        }
        return e.err
}
 
// NewEncoder returns a new base32 stream encoder.  Data written to
// the returned writer will be encoded using enc and then written to w.
// Base32 encodings operate in 5-byte blocks; when finished
// writing, the caller must Close the returned encoder to flush any
// partially written blocks.
func NewEncoder(enc *Encoding, w io.Writer) io.WriteCloser {
        return &encoder{enc: enc, w: w}
}
 
// EncodedLen returns the length in bytes of the base32 encoding
// of an input buffer of length n.
func (enc *Encoding) EncodedLen(n int) int { return (n + 4) / 5 * 8 }
 
/*
 * Decoder
 */
 
type CorruptInputError int64
 
func (e CorruptInputError) Error() string {
        return "illegal base32 data at input byte " + strconv.FormatInt(int64(e), 10)
}
 
// decode is like Decode but returns an additional 'end' value, which
// indicates if end-of-message padding was encountered and thus any
// additional data is an error.
func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err error) {
        osrc := src
        for len(src) > 0 && !end {
                // Decode quantum using the base32 alphabet
                var dbuf [8]byte
                dlen := 8
 
                // do the top bytes contain any data?
        dbufloop:
                for j := 0; j < 8; {
                        if len(src) == 0 {
                                return n, false, CorruptInputError(len(osrc) - len(src) - j)
                        }
                        in := src[0]
                        src = src[1:]
                        if in == '\r' || in == '\n' {
                                // Ignore this character.
                                continue
                        }
                        if in == '=' && j >= 2 && len(src) < 8 {
                                // We've reached the end and there's
                                // padding, the rest should be padded
                                for k := 0; k < 8-j-1; k++ {
                                        if len(src) > k && src[k] != '=' {
                                                return n, false, CorruptInputError(len(osrc) - len(src) + k - 1)
                                        }
                                }
                                dlen = j
                                end = true
                                break dbufloop
                        }
                        dbuf[j] = enc.decodeMap[in]
                        if dbuf[j] == 0xFF {
                                return n, false, CorruptInputError(len(osrc) - len(src) - 1)
                        }
                        j++
                }
 
                // Pack 8x 5-bit source blocks into 5 byte destination
                // quantum
                switch dlen {
                case 7, 8:
                        dst[4] = dbuf[6]<<5 | dbuf[7]
                        fallthrough
                case 6, 5:
                        dst[3] = dbuf[4]<<7 | dbuf[5]<<2 | dbuf[6]>>3
                        fallthrough
                case 4:
                        dst[2] = dbuf[3]<<4 | dbuf[4]>>1
                        fallthrough
                case 3:
                        dst[1] = dbuf[1]<<6 | dbuf[2]<<1 | dbuf[3]>>4
                        fallthrough
                case 2:
                        dst[0] = dbuf[0]<<3 | dbuf[1]>>2
                }
                dst = dst[5:]
                switch dlen {
                case 2:
                        n += 1
                case 3, 4:
                        n += 2
                case 5:
                        n += 3
                case 6, 7:
                        n += 4
                case 8:
                        n += 5
                }
        }
        return n, end, nil
}
 
// Decode decodes src using the encoding enc.  It writes at most
// DecodedLen(len(src)) bytes to dst and returns the number of bytes
// written.  If src contains invalid base32 data, it will return the
// number of bytes successfully written and CorruptInputError.
// New line characters (\r and \n) are ignored.
func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
        n, _, err = enc.decode(dst, src)
        return
}
 
// DecodeString returns the bytes represented by the base32 string s.
func (enc *Encoding) DecodeString(s string) ([]byte, error) {
        dbuf := make([]byte, enc.DecodedLen(len(s)))
        n, err := enc.Decode(dbuf, []byte(s))
        return dbuf[:n], err
}
 
type decoder struct {
        err    error
        enc    *Encoding
        r      io.Reader
        end    bool       // saw end of message
        buf    [1024]byte // leftover input
        nbuf   int
        out    []byte // leftover decoded output
        outbuf [1024 / 8 * 5]byte
}
 
func (d *decoder) Read(p []byte) (n int, err error) {
        if d.err != nil {
                return 0, d.err
        }
 
        // Use leftover decoded output from last read.
        if len(d.out) > 0 {
                n = copy(p, d.out)
                d.out = d.out[n:]
                return n, nil
        }
 
        // Read a chunk.
        nn := len(p) / 5 * 8
        if nn < 8 {
                nn = 8
        }
        if nn > len(d.buf) {
                nn = len(d.buf)
        }
        nn, d.err = io.ReadAtLeast(d.r, d.buf[d.nbuf:nn], 8-d.nbuf)
        d.nbuf += nn
        if d.nbuf < 8 {
                return 0, d.err
        }
 
        // Decode chunk into p, or d.out and then p if p is too small.
        nr := d.nbuf / 8 * 8
        nw := d.nbuf / 8 * 5
        if nw > len(p) {
                nw, d.end, d.err = d.enc.decode(d.outbuf[0:], d.buf[0:nr])
                d.out = d.outbuf[0:nw]
                n = copy(p, d.out)
                d.out = d.out[n:]
        } else {
                n, d.end, d.err = d.enc.decode(p, d.buf[0:nr])
        }
        d.nbuf -= nr
        for i := 0; i < d.nbuf; i++ {
                d.buf[i] = d.buf[i+nr]
        }
 
        if d.err == nil {
                d.err = err
        }
        return n, d.err
}
 
// NewDecoder constructs a new base32 stream decoder.
func NewDecoder(enc *Encoding, r io.Reader) io.Reader {
        return &decoder{enc: enc, r: r}
}
 
// DecodedLen returns the maximum length in bytes of the decoded data
// corresponding to n bytes of base32-encoded data.
func (enc *Encoding) DecodedLen(n int) int { return n / 8 * 5 }

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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [encoding/] [base32/] [base32.go] - Blame information for rev 774

Line No.	Rev	Author	Line
1	747	jeremybenn	`// Copyright 2011 The Go Authors. All rights reserved.`
2			`// Use of this source code is governed by a BSD-style`
3			`// license that can be found in the LICENSE file.`
4
5			`// Package base32 implements base32 encoding as specified by RFC 4648.`
6			`package base32`
7
8			`import (`
9			`"io"`
10			`"strconv"`
11			`)`
12
13			`/*`
14			`* Encodings`
15			`*/`
16
17			`// An Encoding is a radix 32 encoding/decoding scheme, defined by a`
18			`// 32-character alphabet. The most common is the "base32" encoding`
19			`// introduced for SASL GSSAPI and standardized in RFC 4648.`
20			`// The alternate "base32hex" encoding is used in DNSSEC.`
21			`type Encoding struct {`
22			`encode string`
23			`decodeMap [256]byte`
24			`}`
25
26			`const encodeStd = "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567"`
27			`const encodeHex = "0123456789ABCDEFGHIJKLMNOPQRSTUV"`
28
29			`// NewEncoding returns a new Encoding defined by the given alphabet,`
30			`// which must be a 32-byte string.`
31			`func NewEncoding(encoder string) *Encoding {`
32			`e := new(Encoding)`
33			`e.encode = encoder`
34			`for i := 0; i < len(e.decodeMap); i++ {`
35			`e.decodeMap[i] = 0xFF`
36			`}`
37			`for i := 0; i < len(encoder); i++ {`
38			`e.decodeMap[encoder[i]] = byte(i)`
39			`}`
40			`return e`
41			`}`
42
43			`// StdEncoding is the standard base32 encoding, as defined in`
44			`// RFC 4648.`
45			`var StdEncoding = NewEncoding(encodeStd)`
46
47			// HexEncoding is the ``Extended Hex Alphabet'' defined in RFC 4648.
48			`// It is typically used in DNS.`
49			`var HexEncoding = NewEncoding(encodeHex)`
50
51			`/*`
52			`* Encoder`
53			`*/`
54
55			`// Encode encodes src using the encoding enc, writing`
56			`// EncodedLen(len(src)) bytes to dst.`
57			`//`
58			`// The encoding pads the output to a multiple of 8 bytes,`
59			`// so Encode is not appropriate for use on individual blocks`
60			`// of a large data stream. Use NewEncoder() instead.`
61			`func (enc *Encoding) Encode(dst, src []byte) {`
62			`if len(src) == 0 {`
63			`return`
64			`}`
65
66			`for len(src) > 0 {`
67			`dst[0] = 0`
68			`dst[1] = 0`
69			`dst[2] = 0`
70			`dst[3] = 0`
71			`dst[4] = 0`
72			`dst[5] = 0`
73			`dst[6] = 0`
74			`dst[7] = 0`
75
76			`// Unpack 8x 5-bit source blocks into a 5 byte`
77			`// destination quantum`
78			`switch len(src) {`
79			`default:`
80			`dst[7] \|= src[4] & 0x1F`
81			`dst[6] \|= src[4] >> 5`
82			`fallthrough`
83			`case 4:`
84			`dst[6] \|= (src[3] << 3) & 0x1F`
85			`dst[5] \|= (src[3] >> 2) & 0x1F`
86			`dst[4] \|= src[3] >> 7`
87			`fallthrough`
88			`case 3:`
89			`dst[4] \|= (src[2] << 1) & 0x1F`
90			`dst[3] \|= (src[2] >> 4) & 0x1F`
91			`fallthrough`
92			`case 2:`
93			`dst[3] \|= (src[1] << 4) & 0x1F`
94			`dst[2] \|= (src[1] >> 1) & 0x1F`
95			`dst[1] \|= (src[1] >> 6) & 0x1F`
96			`fallthrough`
97			`case 1:`
98			`dst[1] \|= (src[0] << 2) & 0x1F`
99			`dst[0] \|= src[0] >> 3`
100			`}`
101
102			`// Encode 5-bit blocks using the base32 alphabet`
103			`for j := 0; j < 8; j++ {`
104			`dst[j] = enc.encode[dst[j]]`
105			`}`
106
107			`// Pad the final quantum`
108			`if len(src) < 5 {`
109			`dst[7] = '='`
110			`if len(src) < 4 {`
111			`dst[6] = '='`
112			`dst[5] = '='`
113			`if len(src) < 3 {`
114			`dst[4] = '='`
115			`if len(src) < 2 {`
116			`dst[3] = '='`
117			`dst[2] = '='`
118			`}`
119			`}`
120			`}`
121			`break`
122			`}`
123			`src = src[5:]`
124			`dst = dst[8:]`
125			`}`
126			`}`
127
128			`// EncodeToString returns the base32 encoding of src.`
129			`func (enc *Encoding) EncodeToString(src []byte) string {`
130			`buf := make([]byte, enc.EncodedLen(len(src)))`
131			`enc.Encode(buf, src)`
132			`return string(buf)`
133			`}`
134
135			`type encoder struct {`
136			`err error`
137			`enc *Encoding`
138			`w io.Writer`
139			`buf [5]byte // buffered data waiting to be encoded`
140			`nbuf int // number of bytes in buf`
141			`out [1024]byte // output buffer`
142			`}`
143
144			`func (e *encoder) Write(p []byte) (n int, err error) {`
145			`if e.err != nil {`
146			`return 0, e.err`
147			`}`
148
149			`// Leading fringe.`
150			`if e.nbuf > 0 {`
151			`var i int`
152			`for i = 0; i < len(p) && e.nbuf < 5; i++ {`
153			`e.buf[e.nbuf] = p[i]`
154			`e.nbuf++`
155			`}`
156			`n += i`
157			`p = p[i:]`
158			`if e.nbuf < 5 {`
159			`return`
160			`}`
161			`e.enc.Encode(e.out[0:], e.buf[0:])`
162			`if _, e.err = e.w.Write(e.out[0:8]); e.err != nil {`
163			`return n, e.err`
164			`}`
165			`e.nbuf = 0`
166			`}`
167
168			`// Large interior chunks.`
169			`for len(p) >= 5 {`
170			`nn := len(e.out) / 8 * 5`
171			`if nn > len(p) {`
172			`nn = len(p)`
173			`}`
174			`nn -= nn % 5`
175			`if nn > 0 {`
176			`e.enc.Encode(e.out[0:], p[0:nn])`
177			`if _, e.err = e.w.Write(e.out[0 : nn/5*8]); e.err != nil {`
178			`return n, e.err`
179			`}`
180			`}`
181			`n += nn`
182			`p = p[nn:]`
183			`}`
184
185			`// Trailing fringe.`
186			`for i := 0; i < len(p); i++ {`
187			`e.buf[i] = p[i]`
188			`}`
189			`e.nbuf = len(p)`
190			`n += len(p)`
191			`return`
192			`}`
193
194			`// Close flushes any pending output from the encoder.`
195			`// It is an error to call Write after calling Close.`
196			`func (e *encoder) Close() error {`
197			`// If there's anything left in the buffer, flush it out`
198			`if e.err == nil && e.nbuf > 0 {`
199			`e.enc.Encode(e.out[0:], e.buf[0:e.nbuf])`
200			`e.nbuf = 0`
201			`_, e.err = e.w.Write(e.out[0:8])`
202			`}`
203			`return e.err`
204			`}`
205
206			`// NewEncoder returns a new base32 stream encoder. Data written to`
207			`// the returned writer will be encoded using enc and then written to w.`
208			`// Base32 encodings operate in 5-byte blocks; when finished`
209			`// writing, the caller must Close the returned encoder to flush any`
210			`// partially written blocks.`
211			`func NewEncoder(enc *Encoding, w io.Writer) io.WriteCloser {`
212			`return &encoder{enc: enc, w: w}`
213			`}`
214
215			`// EncodedLen returns the length in bytes of the base32 encoding`
216			`// of an input buffer of length n.`
217			`func (enc Encoding) EncodedLen(n int) int { return (n + 4) / 5 8 }`
218
219			`/*`
220			`* Decoder`
221			`*/`
222
223			`type CorruptInputError int64`
224
225			`func (e CorruptInputError) Error() string {`
226			`return "illegal base32 data at input byte " + strconv.FormatInt(int64(e), 10)`
227			`}`
228
229			`// decode is like Decode but returns an additional 'end' value, which`
230			`// indicates if end-of-message padding was encountered and thus any`
231			`// additional data is an error.`
232			`func (enc *Encoding) decode(dst, src []byte) (n int, end bool, err error) {`
233			`osrc := src`
234			`for len(src) > 0 && !end {`
235			`// Decode quantum using the base32 alphabet`
236			`var dbuf [8]byte`
237			`dlen := 8`
238
239			`// do the top bytes contain any data?`
240			`dbufloop:`
241			`for j := 0; j < 8; {`
242			`if len(src) == 0 {`
243			`return n, false, CorruptInputError(len(osrc) - len(src) - j)`
244			`}`
245			`in := src[0]`
246			`src = src[1:]`
247			`if in == '\r' \|\| in == '\n' {`
248			`// Ignore this character.`
249			`continue`
250			`}`
251			`if in == '=' && j >= 2 && len(src) < 8 {`
252			`// We've reached the end and there's`
253			`// padding, the rest should be padded`
254			`for k := 0; k < 8-j-1; k++ {`
255			`if len(src) > k && src[k] != '=' {`
256			`return n, false, CorruptInputError(len(osrc) - len(src) + k - 1)`
257			`}`
258			`}`
259			`dlen = j`
260			`end = true`
261			`break dbufloop`
262			`}`
263			`dbuf[j] = enc.decodeMap[in]`
264			`if dbuf[j] == 0xFF {`
265			`return n, false, CorruptInputError(len(osrc) - len(src) - 1)`
266			`}`
267			`j++`
268			`}`
269
270			`// Pack 8x 5-bit source blocks into 5 byte destination`
271			`// quantum`
272			`switch dlen {`
273			`case 7, 8:`
274			`dst[4] = dbuf[6]<<5 \| dbuf[7]`
275			`fallthrough`
276			`case 6, 5:`
277			`dst[3] = dbuf[4]<<7 \| dbuf[5]<<2 \| dbuf[6]>>3`
278			`fallthrough`
279			`case 4:`
280			`dst[2] = dbuf[3]<<4 \| dbuf[4]>>1`
281			`fallthrough`
282			`case 3:`
283			`dst[1] = dbuf[1]<<6 \| dbuf[2]<<1 \| dbuf[3]>>4`
284			`fallthrough`
285			`case 2:`
286			`dst[0] = dbuf[0]<<3 \| dbuf[1]>>2`
287			`}`
288			`dst = dst[5:]`
289			`switch dlen {`
290			`case 2:`
291			`n += 1`
292			`case 3, 4:`
293			`n += 2`
294			`case 5:`
295			`n += 3`
296			`case 6, 7:`
297			`n += 4`
298			`case 8:`
299			`n += 5`
300			`}`
301			`}`
302			`return n, end, nil`
303			`}`
304
305			`// Decode decodes src using the encoding enc. It writes at most`
306			`// DecodedLen(len(src)) bytes to dst and returns the number of bytes`
307			`// written. If src contains invalid base32 data, it will return the`
308			`// number of bytes successfully written and CorruptInputError.`
309			`// New line characters (\r and \n) are ignored.`
310			`func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {`
311			`n, _, err = enc.decode(dst, src)`
312			`return`
313			`}`
314
315			`// DecodeString returns the bytes represented by the base32 string s.`
316			`func (enc *Encoding) DecodeString(s string) ([]byte, error) {`
317			`dbuf := make([]byte, enc.DecodedLen(len(s)))`
318			`n, err := enc.Decode(dbuf, []byte(s))`
319			`return dbuf[:n], err`
320			`}`
321
322			`type decoder struct {`
323			`err error`
324			`enc *Encoding`
325			`r io.Reader`
326			`end bool // saw end of message`
327			`buf [1024]byte // leftover input`
328			`nbuf int`
329			`out []byte // leftover decoded output`
330			`outbuf [1024 / 8 * 5]byte`
331			`}`
332
333			`func (d *decoder) Read(p []byte) (n int, err error) {`
334			`if d.err != nil {`
335			`return 0, d.err`
336			`}`
337
338			`// Use leftover decoded output from last read.`
339			`if len(d.out) > 0 {`
340			`n = copy(p, d.out)`
341			`d.out = d.out[n:]`
342			`return n, nil`
343			`}`
344
345			`// Read a chunk.`
346			`nn := len(p) / 5 * 8`
347			`if nn < 8 {`
348			`nn = 8`
349			`}`
350			`if nn > len(d.buf) {`
351			`nn = len(d.buf)`
352			`}`
353			`nn, d.err = io.ReadAtLeast(d.r, d.buf[d.nbuf:nn], 8-d.nbuf)`
354			`d.nbuf += nn`
355			`if d.nbuf < 8 {`
356			`return 0, d.err`
357			`}`
358
359			`// Decode chunk into p, or d.out and then p if p is too small.`
360			`nr := d.nbuf / 8 * 8`
361			`nw := d.nbuf / 8 * 5`
362			`if nw > len(p) {`
363			`nw, d.end, d.err = d.enc.decode(d.outbuf[0:], d.buf[0:nr])`
364			`d.out = d.outbuf[0:nw]`
365			`n = copy(p, d.out)`
366			`d.out = d.out[n:]`
367			`} else {`
368			`n, d.end, d.err = d.enc.decode(p, d.buf[0:nr])`
369			`}`
370			`d.nbuf -= nr`
371			`for i := 0; i < d.nbuf; i++ {`
372			`d.buf[i] = d.buf[i+nr]`
373			`}`
374
375			`if d.err == nil {`
376			`d.err = err`
377			`}`
378			`return n, d.err`
379			`}`
380
381			`// NewDecoder constructs a new base32 stream decoder.`
382			`func NewDecoder(enc *Encoding, r io.Reader) io.Reader {`
383			`return &decoder{enc: enc, r: r}`
384			`}`
385
386			`// DecodedLen returns the maximum length in bytes of the decoded data`
387			`// corresponding to n bytes of base32-encoded data.`
388			`func (enc Encoding) DecodedLen(n int) int { return n / 8 5 }`