diff options
Diffstat (limited to 'src/pkg/encoding/ascii85/ascii85.go')
| -rw-r--r-- | src/pkg/encoding/ascii85/ascii85.go | 300 | 
1 files changed, 0 insertions, 300 deletions
| diff --git a/src/pkg/encoding/ascii85/ascii85.go b/src/pkg/encoding/ascii85/ascii85.go deleted file mode 100644 index ead0c2475..000000000 --- a/src/pkg/encoding/ascii85/ascii85.go +++ /dev/null @@ -1,300 +0,0 @@ -// Copyright 2009 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 ascii85 implements the ascii85 data encoding -// as used in the btoa tool and Adobe's PostScript and PDF document formats. -package ascii85 - -import ( -	"io" -	"os" -	"strconv" -) - -/* - * Encoder - */ - -// Encode encodes src into at most MaxEncodedLen(len(src)) -// bytes of dst, returning the actual number of bytes written. -// -// The encoding handles 4-byte chunks, using a special encoding -// for the last fragment, so Encode is not appropriate for use on -// individual blocks of a large data stream.  Use NewEncoder() instead. -// -// Often, ascii85-encoded data is wrapped in <~ and ~> symbols. -// Encode does not add these. -func Encode(dst, src []byte) int { -	if len(src) == 0 { -		return 0 -	} - -	n := 0 -	for len(src) > 0 { -		dst[0] = 0 -		dst[1] = 0 -		dst[2] = 0 -		dst[3] = 0 -		dst[4] = 0 - -		// Unpack 4 bytes into uint32 to repack into base 85 5-byte. -		var v uint32 -		switch len(src) { -		default: -			v |= uint32(src[3]) -			fallthrough -		case 3: -			v |= uint32(src[2]) << 8 -			fallthrough -		case 2: -			v |= uint32(src[1]) << 16 -			fallthrough -		case 1: -			v |= uint32(src[0]) << 24 -		} - -		// Special case: zero (!!!!!) shortens to z. -		if v == 0 && len(src) >= 4 { -			dst[0] = 'z' -			dst = dst[1:] -			n++ -			continue -		} - -		// Otherwise, 5 base 85 digits starting at !. -		for i := 4; i >= 0; i-- { -			dst[i] = '!' + byte(v%85) -			v /= 85 -		} - -		// If src was short, discard the low destination bytes. -		m := 5 -		if len(src) < 4 { -			m -= 4 - len(src) -			src = nil -		} else { -			src = src[4:] -		} -		dst = dst[m:] -		n += m -	} -	return n -} - -// MaxEncodedLen returns the maximum length of an encoding of n source bytes. -func MaxEncodedLen(n int) int { return (n + 3) / 4 * 5 } - -// NewEncoder returns a new ascii85 stream encoder.  Data written to -// the returned writer will be encoded and then written to w. -// Ascii85 encodings operate in 32-bit blocks; when finished -// writing, the caller must Close the returned encoder to flush any -// trailing partial block. -func NewEncoder(w io.Writer) io.WriteCloser { return &encoder{w: w} } - -type encoder struct { -	err  os.Error -	w    io.Writer -	buf  [4]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 os.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 < 4; i++ { -			e.buf[e.nbuf] = p[i] -			e.nbuf++ -		} -		n += i -		p = p[i:] -		if e.nbuf < 4 { -			return -		} -		nout := Encode(e.out[0:], e.buf[0:]) -		if _, e.err = e.w.Write(e.out[0:nout]); e.err != nil { -			return n, e.err -		} -		e.nbuf = 0 -	} - -	// Large interior chunks. -	for len(p) >= 4 { -		nn := len(e.out) / 5 * 4 -		if nn > len(p) { -			nn = len(p) -		} -		nn -= nn % 4 -		if nn > 0 { -			nout := Encode(e.out[0:], p[0:nn]) -			if _, e.err = e.w.Write(e.out[0:nout]); 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() os.Error { -	// If there's anything left in the buffer, flush it out -	if e.err == nil && e.nbuf > 0 { -		nout := Encode(e.out[0:], e.buf[0:e.nbuf]) -		e.nbuf = 0 -		_, e.err = e.w.Write(e.out[0:nout]) -	} -	return e.err -} - -/* - * Decoder - */ - -type CorruptInputError int64 - -func (e CorruptInputError) String() string { -	return "illegal ascii85 data at input byte " + strconv.Itoa64(int64(e)) -} - -// Decode decodes src into dst, returning both the number -// of bytes written to dst and the number consumed from src. -// If src contains invalid ascii85 data, Decode will return the -// number of bytes successfully written and a CorruptInputError. -// Decode ignores space and control characters in src. -// Often, ascii85-encoded data is wrapped in <~ and ~> symbols. -// Decode expects these to have been stripped by the caller. -// -// If flush is true, Decode assumes that src represents the -// end of the input stream and processes it completely rather -// than wait for the completion of another 32-bit block. -// -// NewDecoder wraps an io.Reader interface around Decode. -// -func Decode(dst, src []byte, flush bool) (ndst, nsrc int, err os.Error) { -	var v uint32 -	var nb int -	for i, b := range src { -		if len(dst)-ndst < 4 { -			return -		} -		switch { -		case b <= ' ': -			continue -		case b == 'z' && nb == 0: -			nb = 5 -			v = 0 -		case '!' <= b && b <= 'u': -			v = v*85 + uint32(b-'!') -			nb++ -		default: -			return 0, 0, CorruptInputError(i) -		} -		if nb == 5 { -			nsrc = i + 1 -			dst[ndst] = byte(v >> 24) -			dst[ndst+1] = byte(v >> 16) -			dst[ndst+2] = byte(v >> 8) -			dst[ndst+3] = byte(v) -			ndst += 4 -			nb = 0 -			v = 0 -		} -	} -	if flush { -		nsrc = len(src) -		if nb > 0 { -			// The number of output bytes in the last fragment -			// is the number of leftover input bytes - 1: -			// the extra byte provides enough bits to cover -			// the inefficiency of the encoding for the block. -			if nb == 1 { -				return 0, 0, CorruptInputError(len(src)) -			} -			for i := nb; i < 5; i++ { -				// The short encoding truncated the output value. -				// We have to assume the worst case values (digit 84) -				// in order to ensure that the top bits are correct. -				v = v*85 + 84 -			} -			for i := 0; i < nb-1; i++ { -				dst[ndst] = byte(v >> 24) -				v <<= 8 -				ndst++ -			} -		} -	} -	return -} - -// NewDecoder constructs a new ascii85 stream decoder. -func NewDecoder(r io.Reader) io.Reader { return &decoder{r: r} } - -type decoder struct { -	err     os.Error -	readErr os.Error -	r       io.Reader -	end     bool       // saw end of message -	buf     [1024]byte // leftover input -	nbuf    int -	out     []byte // leftover decoded output -	outbuf  [1024]byte -} - -func (d *decoder) Read(p []byte) (n int, err os.Error) { -	if len(p) == 0 { -		return 0, nil -	} -	if d.err != nil { -		return 0, d.err -	} - -	for { -		// Copy leftover output from last decode. -		if len(d.out) > 0 { -			n = copy(p, d.out) -			d.out = d.out[n:] -			return -		} - -		// Decode leftover input from last read. -		var nn, nsrc, ndst int -		if d.nbuf > 0 { -			ndst, nsrc, d.err = Decode(d.outbuf[0:], d.buf[0:d.nbuf], d.readErr != nil) -			if ndst > 0 { -				d.out = d.outbuf[0:ndst] -				d.nbuf = copy(d.buf[0:], d.buf[nsrc:d.nbuf]) -				continue // copy out and return -			} -		} - -		// Out of input, out of decoded output.  Check errors. -		if d.err != nil { -			return 0, d.err -		} -		if d.readErr != nil { -			d.err = d.readErr -			return 0, d.err -		} - -		// Read more data. -		nn, d.readErr = d.r.Read(d.buf[d.nbuf:]) -		d.nbuf += nn -	} -	panic("unreachable") -} | 
