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-rw-r--r--vendor/github.com/golang/snappy/AUTHORS15
-rw-r--r--vendor/github.com/golang/snappy/CONTRIBUTORS37
-rw-r--r--vendor/github.com/golang/snappy/LICENSE27
-rw-r--r--vendor/github.com/golang/snappy/README107
-rw-r--r--vendor/github.com/golang/snappy/decode.go237
-rw-r--r--vendor/github.com/golang/snappy/decode_amd64.go14
-rw-r--r--vendor/github.com/golang/snappy/decode_amd64.s490
-rw-r--r--vendor/github.com/golang/snappy/encode.go285
-rw-r--r--vendor/github.com/golang/snappy/encode_amd64.go29
-rw-r--r--vendor/github.com/golang/snappy/encode_amd64.s730
-rw-r--r--vendor/github.com/golang/snappy/snappy.go87
11 files changed, 2058 insertions, 0 deletions
diff --git a/vendor/github.com/golang/snappy/AUTHORS b/vendor/github.com/golang/snappy/AUTHORS
new file mode 100644
index 0000000..bcfa195
--- /dev/null
+++ b/vendor/github.com/golang/snappy/AUTHORS
@@ -0,0 +1,15 @@
+# This is the official list of Snappy-Go authors for copyright purposes.
+# This file is distinct from the CONTRIBUTORS files.
+# See the latter for an explanation.
+
+# Names should be added to this file as
+# Name or Organization <email address>
+# The email address is not required for organizations.
+
+# Please keep the list sorted.
+
+Damian Gryski <dgryski@gmail.com>
+Google Inc.
+Jan Mercl <0xjnml@gmail.com>
+Rodolfo Carvalho <rhcarvalho@gmail.com>
+Sebastien Binet <seb.binet@gmail.com>
diff --git a/vendor/github.com/golang/snappy/CONTRIBUTORS b/vendor/github.com/golang/snappy/CONTRIBUTORS
new file mode 100644
index 0000000..931ae31
--- /dev/null
+++ b/vendor/github.com/golang/snappy/CONTRIBUTORS
@@ -0,0 +1,37 @@
+# This is the official list of people who can contribute
+# (and typically have contributed) code to the Snappy-Go repository.
+# The AUTHORS file lists the copyright holders; this file
+# lists people. For example, Google employees are listed here
+# but not in AUTHORS, because Google holds the copyright.
+#
+# The submission process automatically checks to make sure
+# that people submitting code are listed in this file (by email address).
+#
+# Names should be added to this file only after verifying that
+# the individual or the individual's organization has agreed to
+# the appropriate Contributor License Agreement, found here:
+#
+# http://code.google.com/legal/individual-cla-v1.0.html
+# http://code.google.com/legal/corporate-cla-v1.0.html
+#
+# The agreement for individuals can be filled out on the web.
+#
+# When adding J Random Contributor's name to this file,
+# either J's name or J's organization's name should be
+# added to the AUTHORS file, depending on whether the
+# individual or corporate CLA was used.
+
+# Names should be added to this file like so:
+# Name <email address>
+
+# Please keep the list sorted.
+
+Damian Gryski <dgryski@gmail.com>
+Jan Mercl <0xjnml@gmail.com>
+Kai Backman <kaib@golang.org>
+Marc-Antoine Ruel <maruel@chromium.org>
+Nigel Tao <nigeltao@golang.org>
+Rob Pike <r@golang.org>
+Rodolfo Carvalho <rhcarvalho@gmail.com>
+Russ Cox <rsc@golang.org>
+Sebastien Binet <seb.binet@gmail.com>
diff --git a/vendor/github.com/golang/snappy/LICENSE b/vendor/github.com/golang/snappy/LICENSE
new file mode 100644
index 0000000..6050c10
--- /dev/null
+++ b/vendor/github.com/golang/snappy/LICENSE
@@ -0,0 +1,27 @@
+Copyright (c) 2011 The Snappy-Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+ * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+ * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+ * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/github.com/golang/snappy/README b/vendor/github.com/golang/snappy/README
new file mode 100644
index 0000000..cea1287
--- /dev/null
+++ b/vendor/github.com/golang/snappy/README
@@ -0,0 +1,107 @@
+The Snappy compression format in the Go programming language.
+
+To download and install from source:
+$ go get github.com/golang/snappy
+
+Unless otherwise noted, the Snappy-Go source files are distributed
+under the BSD-style license found in the LICENSE file.
+
+
+
+Benchmarks.
+
+The golang/snappy benchmarks include compressing (Z) and decompressing (U) ten
+or so files, the same set used by the C++ Snappy code (github.com/google/snappy
+and note the "google", not "golang"). On an "Intel(R) Core(TM) i7-3770 CPU @
+3.40GHz", Go's GOARCH=amd64 numbers as of 2016-05-29:
+
+"go test -test.bench=."
+
+_UFlat0-8 2.19GB/s ± 0% html
+_UFlat1-8 1.41GB/s ± 0% urls
+_UFlat2-8 23.5GB/s ± 2% jpg
+_UFlat3-8 1.91GB/s ± 0% jpg_200
+_UFlat4-8 14.0GB/s ± 1% pdf
+_UFlat5-8 1.97GB/s ± 0% html4
+_UFlat6-8 814MB/s ± 0% txt1
+_UFlat7-8 785MB/s ± 0% txt2
+_UFlat8-8 857MB/s ± 0% txt3
+_UFlat9-8 719MB/s ± 1% txt4
+_UFlat10-8 2.84GB/s ± 0% pb
+_UFlat11-8 1.05GB/s ± 0% gaviota
+
+_ZFlat0-8 1.04GB/s ± 0% html
+_ZFlat1-8 534MB/s ± 0% urls
+_ZFlat2-8 15.7GB/s ± 1% jpg
+_ZFlat3-8 740MB/s ± 3% jpg_200
+_ZFlat4-8 9.20GB/s ± 1% pdf
+_ZFlat5-8 991MB/s ± 0% html4
+_ZFlat6-8 379MB/s ± 0% txt1
+_ZFlat7-8 352MB/s ± 0% txt2
+_ZFlat8-8 396MB/s ± 1% txt3
+_ZFlat9-8 327MB/s ± 1% txt4
+_ZFlat10-8 1.33GB/s ± 1% pb
+_ZFlat11-8 605MB/s ± 1% gaviota
+
+
+
+"go test -test.bench=. -tags=noasm"
+
+_UFlat0-8 621MB/s ± 2% html
+_UFlat1-8 494MB/s ± 1% urls
+_UFlat2-8 23.2GB/s ± 1% jpg
+_UFlat3-8 1.12GB/s ± 1% jpg_200
+_UFlat4-8 4.35GB/s ± 1% pdf
+_UFlat5-8 609MB/s ± 0% html4
+_UFlat6-8 296MB/s ± 0% txt1
+_UFlat7-8 288MB/s ± 0% txt2
+_UFlat8-8 309MB/s ± 1% txt3
+_UFlat9-8 280MB/s ± 1% txt4
+_UFlat10-8 753MB/s ± 0% pb
+_UFlat11-8 400MB/s ± 0% gaviota
+
+_ZFlat0-8 409MB/s ± 1% html
+_ZFlat1-8 250MB/s ± 1% urls
+_ZFlat2-8 12.3GB/s ± 1% jpg
+_ZFlat3-8 132MB/s ± 0% jpg_200
+_ZFlat4-8 2.92GB/s ± 0% pdf
+_ZFlat5-8 405MB/s ± 1% html4
+_ZFlat6-8 179MB/s ± 1% txt1
+_ZFlat7-8 170MB/s ± 1% txt2
+_ZFlat8-8 189MB/s ± 1% txt3
+_ZFlat9-8 164MB/s ± 1% txt4
+_ZFlat10-8 479MB/s ± 1% pb
+_ZFlat11-8 270MB/s ± 1% gaviota
+
+
+
+For comparison (Go's encoded output is byte-for-byte identical to C++'s), here
+are the numbers from C++ Snappy's
+
+make CXXFLAGS="-O2 -DNDEBUG -g" clean snappy_unittest.log && cat snappy_unittest.log
+
+BM_UFlat/0 2.4GB/s html
+BM_UFlat/1 1.4GB/s urls
+BM_UFlat/2 21.8GB/s jpg
+BM_UFlat/3 1.5GB/s jpg_200
+BM_UFlat/4 13.3GB/s pdf
+BM_UFlat/5 2.1GB/s html4
+BM_UFlat/6 1.0GB/s txt1
+BM_UFlat/7 959.4MB/s txt2
+BM_UFlat/8 1.0GB/s txt3
+BM_UFlat/9 864.5MB/s txt4
+BM_UFlat/10 2.9GB/s pb
+BM_UFlat/11 1.2GB/s gaviota
+
+BM_ZFlat/0 944.3MB/s html (22.31 %)
+BM_ZFlat/1 501.6MB/s urls (47.78 %)
+BM_ZFlat/2 14.3GB/s jpg (99.95 %)
+BM_ZFlat/3 538.3MB/s jpg_200 (73.00 %)
+BM_ZFlat/4 8.3GB/s pdf (83.30 %)
+BM_ZFlat/5 903.5MB/s html4 (22.52 %)
+BM_ZFlat/6 336.0MB/s txt1 (57.88 %)
+BM_ZFlat/7 312.3MB/s txt2 (61.91 %)
+BM_ZFlat/8 353.1MB/s txt3 (54.99 %)
+BM_ZFlat/9 289.9MB/s txt4 (66.26 %)
+BM_ZFlat/10 1.2GB/s pb (19.68 %)
+BM_ZFlat/11 527.4MB/s gaviota (37.72 %)
diff --git a/vendor/github.com/golang/snappy/decode.go b/vendor/github.com/golang/snappy/decode.go
new file mode 100644
index 0000000..72efb03
--- /dev/null
+++ b/vendor/github.com/golang/snappy/decode.go
@@ -0,0 +1,237 @@
+// Copyright 2011 The Snappy-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 snappy
+
+import (
+ "encoding/binary"
+ "errors"
+ "io"
+)
+
+var (
+ // ErrCorrupt reports that the input is invalid.
+ ErrCorrupt = errors.New("snappy: corrupt input")
+ // ErrTooLarge reports that the uncompressed length is too large.
+ ErrTooLarge = errors.New("snappy: decoded block is too large")
+ // ErrUnsupported reports that the input isn't supported.
+ ErrUnsupported = errors.New("snappy: unsupported input")
+
+ errUnsupportedLiteralLength = errors.New("snappy: unsupported literal length")
+)
+
+// DecodedLen returns the length of the decoded block.
+func DecodedLen(src []byte) (int, error) {
+ v, _, err := decodedLen(src)
+ return v, err
+}
+
+// decodedLen returns the length of the decoded block and the number of bytes
+// that the length header occupied.
+func decodedLen(src []byte) (blockLen, headerLen int, err error) {
+ v, n := binary.Uvarint(src)
+ if n <= 0 || v > 0xffffffff {
+ return 0, 0, ErrCorrupt
+ }
+
+ const wordSize = 32 << (^uint(0) >> 32 & 1)
+ if wordSize == 32 && v > 0x7fffffff {
+ return 0, 0, ErrTooLarge
+ }
+ return int(v), n, nil
+}
+
+const (
+ decodeErrCodeCorrupt = 1
+ decodeErrCodeUnsupportedLiteralLength = 2
+)
+
+// Decode returns the decoded form of src. The returned slice may be a sub-
+// slice of dst if dst was large enough to hold the entire decoded block.
+// Otherwise, a newly allocated slice will be returned.
+//
+// The dst and src must not overlap. It is valid to pass a nil dst.
+func Decode(dst, src []byte) ([]byte, error) {
+ dLen, s, err := decodedLen(src)
+ if err != nil {
+ return nil, err
+ }
+ if dLen <= len(dst) {
+ dst = dst[:dLen]
+ } else {
+ dst = make([]byte, dLen)
+ }
+ switch decode(dst, src[s:]) {
+ case 0:
+ return dst, nil
+ case decodeErrCodeUnsupportedLiteralLength:
+ return nil, errUnsupportedLiteralLength
+ }
+ return nil, ErrCorrupt
+}
+
+// NewReader returns a new Reader that decompresses from r, using the framing
+// format described at
+// https://github.com/google/snappy/blob/master/framing_format.txt
+func NewReader(r io.Reader) *Reader {
+ return &Reader{
+ r: r,
+ decoded: make([]byte, maxBlockSize),
+ buf: make([]byte, maxEncodedLenOfMaxBlockSize+checksumSize),
+ }
+}
+
+// Reader is an io.Reader that can read Snappy-compressed bytes.
+type Reader struct {
+ r io.Reader
+ err error
+ decoded []byte
+ buf []byte
+ // decoded[i:j] contains decoded bytes that have not yet been passed on.
+ i, j int
+ readHeader bool
+}
+
+// Reset discards any buffered data, resets all state, and switches the Snappy
+// reader to read from r. This permits reusing a Reader rather than allocating
+// a new one.
+func (r *Reader) Reset(reader io.Reader) {
+ r.r = reader
+ r.err = nil
+ r.i = 0
+ r.j = 0
+ r.readHeader = false
+}
+
+func (r *Reader) readFull(p []byte, allowEOF bool) (ok bool) {
+ if _, r.err = io.ReadFull(r.r, p); r.err != nil {
+ if r.err == io.ErrUnexpectedEOF || (r.err == io.EOF && !allowEOF) {
+ r.err = ErrCorrupt
+ }
+ return false
+ }
+ return true
+}
+
+// Read satisfies the io.Reader interface.
+func (r *Reader) Read(p []byte) (int, error) {
+ if r.err != nil {
+ return 0, r.err
+ }
+ for {
+ if r.i < r.j {
+ n := copy(p, r.decoded[r.i:r.j])
+ r.i += n
+ return n, nil
+ }
+ if !r.readFull(r.buf[:4], true) {
+ return 0, r.err
+ }
+ chunkType := r.buf[0]
+ if !r.readHeader {
+ if chunkType != chunkTypeStreamIdentifier {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ r.readHeader = true
+ }
+ chunkLen := int(r.buf[1]) | int(r.buf[2])<<8 | int(r.buf[3])<<16
+ if chunkLen > len(r.buf) {
+ r.err = ErrUnsupported
+ return 0, r.err
+ }
+
+ // The chunk types are specified at
+ // https://github.com/google/snappy/blob/master/framing_format.txt
+ switch chunkType {
+ case chunkTypeCompressedData:
+ // Section 4.2. Compressed data (chunk type 0x00).
+ if chunkLen < checksumSize {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ buf := r.buf[:chunkLen]
+ if !r.readFull(buf, false) {
+ return 0, r.err
+ }
+ checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
+ buf = buf[checksumSize:]
+
+ n, err := DecodedLen(buf)
+ if err != nil {
+ r.err = err
+ return 0, r.err
+ }
+ if n > len(r.decoded) {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ if _, err := Decode(r.decoded, buf); err != nil {
+ r.err = err
+ return 0, r.err
+ }
+ if crc(r.decoded[:n]) != checksum {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ r.i, r.j = 0, n
+ continue
+
+ case chunkTypeUncompressedData:
+ // Section 4.3. Uncompressed data (chunk type 0x01).
+ if chunkLen < checksumSize {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ buf := r.buf[:checksumSize]
+ if !r.readFull(buf, false) {
+ return 0, r.err
+ }
+ checksum := uint32(buf[0]) | uint32(buf[1])<<8 | uint32(buf[2])<<16 | uint32(buf[3])<<24
+ // Read directly into r.decoded instead of via r.buf.
+ n := chunkLen - checksumSize
+ if n > len(r.decoded) {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ if !r.readFull(r.decoded[:n], false) {
+ return 0, r.err
+ }
+ if crc(r.decoded[:n]) != checksum {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ r.i, r.j = 0, n
+ continue
+
+ case chunkTypeStreamIdentifier:
+ // Section 4.1. Stream identifier (chunk type 0xff).
+ if chunkLen != len(magicBody) {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ if !r.readFull(r.buf[:len(magicBody)], false) {
+ return 0, r.err
+ }
+ for i := 0; i < len(magicBody); i++ {
+ if r.buf[i] != magicBody[i] {
+ r.err = ErrCorrupt
+ return 0, r.err
+ }
+ }
+ continue
+ }
+
+ if chunkType <= 0x7f {
+ // Section 4.5. Reserved unskippable chunks (chunk types 0x02-0x7f).
+ r.err = ErrUnsupported
+ return 0, r.err
+ }
+ // Section 4.4 Padding (chunk type 0xfe).
+ // Section 4.6. Reserved skippable chunks (chunk types 0x80-0xfd).
+ if !r.readFull(r.buf[:chunkLen], false) {
+ return 0, r.err
+ }
+ }
+}
diff --git a/vendor/github.com/golang/snappy/decode_amd64.go b/vendor/github.com/golang/snappy/decode_amd64.go
new file mode 100644
index 0000000..fcd192b
--- /dev/null
+++ b/vendor/github.com/golang/snappy/decode_amd64.go
@@ -0,0 +1,14 @@
+// Copyright 2016 The Snappy-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.
+
+// +build !appengine
+// +build gc
+// +build !noasm
+
+package snappy
+
+// decode has the same semantics as in decode_other.go.
+//
+//go:noescape
+func decode(dst, src []byte) int
diff --git a/vendor/github.com/golang/snappy/decode_amd64.s b/vendor/github.com/golang/snappy/decode_amd64.s
new file mode 100644
index 0000000..e6179f6
--- /dev/null
+++ b/vendor/github.com/golang/snappy/decode_amd64.s
@@ -0,0 +1,490 @@
+// Copyright 2016 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.
+
+// +build !appengine
+// +build gc
+// +build !noasm
+
+#include "textflag.h"
+
+// The asm code generally follows the pure Go code in decode_other.go, except
+// where marked with a "!!!".
+
+// func decode(dst, src []byte) int
+//
+// All local variables fit into registers. The non-zero stack size is only to
+// spill registers and push args when issuing a CALL. The register allocation:
+// - AX scratch
+// - BX scratch
+// - CX length or x
+// - DX offset
+// - SI &src[s]
+// - DI &dst[d]
+// + R8 dst_base
+// + R9 dst_len
+// + R10 dst_base + dst_len
+// + R11 src_base
+// + R12 src_len
+// + R13 src_base + src_len
+// - R14 used by doCopy
+// - R15 used by doCopy
+//
+// The registers R8-R13 (marked with a "+") are set at the start of the
+// function, and after a CALL returns, and are not otherwise modified.
+//
+// The d variable is implicitly DI - R8, and len(dst)-d is R10 - DI.
+// The s variable is implicitly SI - R11, and len(src)-s is R13 - SI.
+TEXT ·decode(SB), NOSPLIT, $48-56
+ // Initialize SI, DI and R8-R13.
+ MOVQ dst_base+0(FP), R8
+ MOVQ dst_len+8(FP), R9
+ MOVQ R8, DI
+ MOVQ R8, R10
+ ADDQ R9, R10
+ MOVQ src_base+24(FP), R11
+ MOVQ src_len+32(FP), R12
+ MOVQ R11, SI
+ MOVQ R11, R13
+ ADDQ R12, R13
+
+loop:
+ // for s < len(src)
+ CMPQ SI, R13
+ JEQ end
+
+ // CX = uint32(src[s])
+ //
+ // switch src[s] & 0x03
+ MOVBLZX (SI), CX
+ MOVL CX, BX
+ ANDL $3, BX
+ CMPL BX, $1
+ JAE tagCopy
+
+ // ----------------------------------------
+ // The code below handles literal tags.
+
+ // case tagLiteral:
+ // x := uint32(src[s] >> 2)
+ // switch
+ SHRL $2, CX
+ CMPL CX, $60
+ JAE tagLit60Plus
+
+ // case x < 60:
+ // s++
+ INCQ SI
+
+doLit:
+ // This is the end of the inner "switch", when we have a literal tag.
+ //
+ // We assume that CX == x and x fits in a uint32, where x is the variable
+ // used in the pure Go decode_other.go code.
+
+ // length = int(x) + 1
+ //
+ // Unlike the pure Go code, we don't need to check if length <= 0 because
+ // CX can hold 64 bits, so the increment cannot overflow.
+ INCQ CX
+
+ // Prepare to check if copying length bytes will run past the end of dst or
+ // src.
+ //
+ // AX = len(dst) - d
+ // BX = len(src) - s
+ MOVQ R10, AX
+ SUBQ DI, AX
+ MOVQ R13, BX
+ SUBQ SI, BX
+
+ // !!! Try a faster technique for short (16 or fewer bytes) copies.
+ //
+ // if length > 16 || len(dst)-d < 16 || len(src)-s < 16 {
+ // goto callMemmove // Fall back on calling runtime·memmove.
+ // }
+ //
+ // The C++ snappy code calls this TryFastAppend. It also checks len(src)-s
+ // against 21 instead of 16, because it cannot assume that all of its input
+ // is contiguous in memory and so it needs to leave enough source bytes to
+ // read the next tag without refilling buffers, but Go's Decode assumes
+ // contiguousness (the src argument is a []byte).
+ CMPQ CX, $16
+ JGT callMemmove
+ CMPQ AX, $16
+ JLT callMemmove
+ CMPQ BX, $16
+ JLT callMemmove
+
+ // !!! Implement the copy from src to dst as a 16-byte load and store.
+ // (Decode's documentation says that dst and src must not overlap.)
+ //
+ // This always copies 16 bytes, instead of only length bytes, but that's
+ // OK. If the input is a valid Snappy encoding then subsequent iterations
+ // will fix up the overrun. Otherwise, Decode returns a nil []byte (and a
+ // non-nil error), so the overrun will be ignored.
+ //
+ // Note that on amd64, it is legal and cheap to issue unaligned 8-byte or
+ // 16-byte loads and stores. This technique probably wouldn't be as
+ // effective on architectures that are fussier about alignment.
+ MOVOU 0(SI), X0
+ MOVOU X0, 0(DI)
+
+ // d += length
+ // s += length
+ ADDQ CX, DI
+ ADDQ CX, SI
+ JMP loop
+
+callMemmove:
+ // if length > len(dst)-d || length > len(src)-s { etc }
+ CMPQ CX, AX
+ JGT errCorrupt
+ CMPQ CX, BX
+ JGT errCorrupt
+
+ // copy(dst[d:], src[s:s+length])
+ //
+ // This means calling runtime·memmove(&dst[d], &src[s], length), so we push
+ // DI, SI and CX as arguments. Coincidentally, we also need to spill those
+ // three registers to the stack, to save local variables across the CALL.
+ MOVQ DI, 0(SP)
+ MOVQ SI, 8(SP)
+ MOVQ CX, 16(SP)
+ MOVQ DI, 24(SP)
+ MOVQ SI, 32(SP)
+ MOVQ CX, 40(SP)
+ CALL runtime·memmove(SB)
+
+ // Restore local variables: unspill registers from the stack and
+ // re-calculate R8-R13.
+ MOVQ 24(SP), DI
+ MOVQ 32(SP), SI
+ MOVQ 40(SP), CX
+ MOVQ dst_base+0(FP), R8
+ MOVQ dst_len+8(FP), R9
+ MOVQ R8, R10
+ ADDQ R9, R10
+ MOVQ src_base+24(FP), R11
+ MOVQ src_len+32(FP), R12
+ MOVQ R11, R13
+ ADDQ R12, R13
+
+ // d += length
+ // s += length
+ ADDQ CX, DI
+ ADDQ CX, SI
+ JMP loop
+
+tagLit60Plus:
+ // !!! This fragment does the
+ //
+ // s += x - 58; if uint(s) > uint(len(src)) { etc }
+ //
+ // checks. In the asm version, we code it once instead of once per switch case.
+ ADDQ CX, SI
+ SUBQ $58, SI
+ MOVQ SI, BX
+ SUBQ R11, BX
+ CMPQ BX, R12
+ JA errCorrupt
+
+ // case x == 60:
+ CMPL CX, $61
+ JEQ tagLit61
+ JA tagLit62Plus
+
+ // x = uint32(src[s-1])
+ MOVBLZX -1(SI), CX
+ JMP doLit
+
+tagLit61:
+ // case x == 61:
+ // x = uint32(src[s-2]) | uint32(src[s-1])<<8
+ MOVWLZX -2(SI), CX
+ JMP doLit
+
+tagLit62Plus:
+ CMPL CX, $62
+ JA tagLit63
+
+ // case x == 62:
+ // x = uint32(src[s-3]) | uint32(src[s-2])<<8 | uint32(src[s-1])<<16
+ MOVWLZX -3(SI), CX
+ MOVBLZX -1(SI), BX
+ SHLL $16, BX
+ ORL BX, CX
+ JMP doLit
+
+tagLit63:
+ // case x == 63:
+ // x = uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24
+ MOVL -4(SI), CX
+ JMP doLit
+
+// The code above handles literal tags.
+// ----------------------------------------
+// The code below handles copy tags.
+
+tagCopy4:
+ // case tagCopy4:
+ // s += 5
+ ADDQ $5, SI
+
+ // if uint(s) > uint(len(src)) { etc }
+ MOVQ SI, BX
+ SUBQ R11, BX
+ CMPQ BX, R12
+ JA errCorrupt
+
+ // length = 1 + int(src[s-5])>>2
+ SHRQ $2, CX
+ INCQ CX
+
+ // offset = int(uint32(src[s-4]) | uint32(src[s-3])<<8 | uint32(src[s-2])<<16 | uint32(src[s-1])<<24)
+ MOVLQZX -4(SI), DX
+ JMP doCopy
+
+tagCopy2:
+ // case tagCopy2:
+ // s += 3
+ ADDQ $3, SI
+
+ // if uint(s) > uint(len(src)) { etc }
+ MOVQ SI, BX
+ SUBQ R11, BX
+ CMPQ BX, R12
+ JA errCorrupt
+
+ // length = 1 + int(src[s-3])>>2
+ SHRQ $2, CX
+ INCQ CX
+
+ // offset = int(uint32(src[s-2]) | uint32(src[s-1])<<8)
+ MOVWQZX -2(SI), DX
+ JMP doCopy
+
+tagCopy:
+ // We have a copy tag. We assume that:
+ // - BX == src[s] & 0x03
+ // - CX == src[s]
+ CMPQ BX, $2
+ JEQ tagCopy2
+ JA tagCopy4
+
+ // case tagCopy1:
+ // s += 2
+ ADDQ $2, SI
+
+ // if uint(s) > uint(len(src)) { etc }
+ MOVQ SI, BX
+ SUBQ R11, BX
+ CMPQ BX, R12
+ JA errCorrupt
+
+ // offset = int(uint32(src[s-2])&0xe0<<3 | uint32(src[s-1]))
+ MOVQ CX, DX
+ ANDQ $0xe0, DX
+ SHLQ $3, DX
+ MOVBQZX -1(SI), BX
+ ORQ BX, DX
+
+ // length = 4 + int(src[s-2])>>2&0x7
+ SHRQ $2, CX
+ ANDQ $7, CX
+ ADDQ $4, CX
+
+doCopy:
+ // This is the end of the outer "switch", when we have a copy tag.
+ //
+ // We assume that:
+ // - CX == length && CX > 0
+ // - DX == offset
+
+ // if offset <= 0 { etc }
+ CMPQ DX, $0
+ JLE errCorrupt
+
+ // if d < offset { etc }
+ MOVQ DI, BX
+ SUBQ R8, BX
+ CMPQ BX, DX
+ JLT errCorrupt
+
+ // if length > len(dst)-d { etc }
+ MOVQ R10, BX
+ SUBQ DI, BX
+ CMPQ CX, BX
+ JGT errCorrupt
+
+ // forwardCopy(dst[d:d+length], dst[d-offset:]); d += length
+ //
+ // Set:
+ // - R14 = len(dst)-d
+ // - R15 = &dst[d-offset]
+ MOVQ R10, R14
+ SUBQ DI, R14
+ MOVQ DI, R15
+ SUBQ DX, R15
+
+ // !!! Try a faster technique for short (16 or fewer bytes) forward copies.
+ //
+ // First, try using two 8-byte load/stores, similar to the doLit technique
+ // above. Even if dst[d:d+length] and dst[d-offset:] can overlap, this is
+ // still OK if offset >= 8. Note that this has to be two 8-byte load/stores
+ // and not one 16-byte load/store, and the first store has to be before the
+ // second load, due to the overlap if offset is in the range [8, 16).
+ //
+ // if length > 16 || offset < 8 || len(dst)-d < 16 {
+ // goto slowForwardCopy
+ // }
+ // copy 16 bytes
+ // d += length
+ CMPQ CX, $16
+ JGT slowForwardCopy
+ CMPQ DX, $8
+ JLT slowForwardCopy
+ CMPQ R14, $16
+ JLT slowForwardCopy
+ MOVQ 0(R15), AX
+ MOVQ AX, 0(DI)
+ MOVQ 8(R15), BX
+ MOVQ BX, 8(DI)
+ ADDQ CX, DI
+ JMP loop
+
+slowForwardCopy:
+ // !!! If the forward copy is longer than 16 bytes, or if offset < 8, we
+ // can still try 8-byte load stores, provided we can overrun up to 10 extra
+ // bytes. As above, the overrun will be fixed up by subsequent iterations
+ // of the outermost loop.
+ //
+ // The C++ snappy code calls this technique IncrementalCopyFastPath. Its
+ // commentary says:
+ //
+ // ----
+ //
+ // The main part of this loop is a simple copy of eight bytes at a time
+ // until we've copied (at least) the requested amount of bytes. However,
+ // if d and d-offset are less than eight bytes apart (indicating a
+ // repeating pattern of length < 8), we first need to expand the pattern in
+ // order to get the correct results. For instance, if the buffer looks like
+ // this, with the eight-byte <d-offset> and <d> patterns marked as
+ // intervals:
+ //
+ // abxxxxxxxxxxxx
+ // [------] d-offset
+ // [------] d
+ //
+ // a single eight-byte copy from <d-offset> to <d> will repeat the pattern
+ // once, after which we can move <d> two bytes without moving <d-offset>:
+ //
+ // ababxxxxxxxxxx
+ // [------] d-offset
+ // [------] d
+ //
+ // and repeat the exercise until the two no longer overlap.
+ //
+ // This allows us to do very well in the special case of one single byte
+ // repeated many times, without taking a big hit for more general cases.
+ //
+ // The worst case of extra writing past the end of the match occurs when
+ // offset == 1 and length == 1; the last copy will read from byte positions
+ // [0..7] and write to [4..11], whereas it was only supposed to write to
+ // position 1. Thus, ten excess bytes.
+ //
+ // ----
+ //
+ // That "10 byte overrun" worst case is confirmed by Go's
+ // TestSlowForwardCopyOverrun, which also tests the fixUpSlowForwardCopy
+ // and finishSlowForwardCopy algorithm.
+ //
+ // if length > len(dst)-d-10 {
+ // goto verySlowForwardCopy
+ // }
+ SUBQ $10, R14
+ CMPQ CX, R14
+ JGT verySlowForwardCopy
+
+makeOffsetAtLeast8:
+ // !!! As above, expand the pattern so that offset >= 8 and we can use
+ // 8-byte load/stores.
+ //
+ // for offset < 8 {
+ // copy 8 bytes from dst[d-offset:] to dst[d:]
+ // length -= offset
+ // d += offset
+ // offset += offset
+ // // The two previous lines together means that d-offset, and therefore
+ // // R15, is unchanged.
+ // }
+ CMPQ DX, $8
+ JGE fixUpSlowForwardCopy
+ MOVQ (R15), BX
+ MOVQ BX, (DI)
+ SUBQ DX, CX
+ ADDQ DX, DI
+ ADDQ DX, DX
+ JMP makeOffsetAtLeast8
+
+fixUpSlowForwardCopy:
+ // !!! Add length (which might be negative now) to d (implied by DI being
+ // &dst[d]) so that d ends up at the right place when we jump back to the
+ // top of the loop. Before we do that, though, we save DI to AX so that, if
+ // length is positive, copying the remaining length bytes will write to the
+ // right place.
+ MOVQ DI, AX
+ ADDQ CX, DI
+
+finishSlowForwardCopy:
+ // !!! Repeat 8-byte load/stores until length <= 0. Ending with a negative
+ // length means that we overrun, but as above, that will be fixed up by
+ // subsequent iterations of the outermost loop.
+ CMPQ CX, $0
+ JLE loop
+ MOVQ (R15), BX
+ MOVQ BX, (AX)
+ ADDQ $8, R15
+ ADDQ $8, AX
+ SUBQ $8, CX
+ JMP finishSlowForwardCopy
+
+verySlowForwardCopy:
+ // verySlowForwardCopy is a simple implementation of forward copy. In C
+ // parlance, this is a do/while loop instead of a while loop, since we know
+ // that length > 0. In Go syntax:
+ //
+ // for {
+ // dst[d] = dst[d - offset]
+ // d++
+ // length--
+ // if length == 0 {
+ // break
+ // }
+ // }
+ MOVB (R15), BX
+ MOVB BX, (DI)
+ INCQ R15
+ INCQ DI
+ DECQ CX
+ JNZ verySlowForwardCopy
+ JMP loop
+
+// The code above handles copy tags.
+// ----------------------------------------
+
+end:
+ // This is the end of the "for s < len(src)".
+ //
+ // if d != len(dst) { etc }
+ CMPQ DI, R10
+ JNE errCorrupt
+
+ // return 0
+ MOVQ $0, ret+48(FP)
+ RET
+
+errCorrupt:
+ // return decodeErrCodeCorrupt
+ MOVQ $1, ret+48(FP)
+ RET
diff --git a/vendor/github.com/golang/snappy/encode.go b/vendor/github.com/golang/snappy/encode.go
new file mode 100644
index 0000000..8d393e9
--- /dev/null
+++ b/vendor/github.com/golang/snappy/encode.go
@@ -0,0 +1,285 @@
+// Copyright 2011 The Snappy-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 snappy
+
+import (
+ "encoding/binary"
+ "errors"
+ "io"
+)
+
+// Encode returns the encoded form of src. The returned slice may be a sub-
+// slice of dst if dst was large enough to hold the entire encoded block.
+// Otherwise, a newly allocated slice will be returned.
+//
+// The dst and src must not overlap. It is valid to pass a nil dst.
+func Encode(dst, src []byte) []byte {
+ if n := MaxEncodedLen(len(src)); n < 0 {
+ panic(ErrTooLarge)
+ } else if len(dst) < n {
+ dst = make([]byte, n)
+ }
+
+ // The block starts with the varint-encoded length of the decompressed bytes.
+ d := binary.PutUvarint(dst, uint64(len(src)))
+
+ for len(src) > 0 {
+ p := src
+ src = nil
+ if len(p) > maxBlockSize {
+ p, src = p[:maxBlockSize], p[maxBlockSize:]
+ }
+ if len(p) < minNonLiteralBlockSize {
+ d += emitLiteral(dst[d:], p)
+ } else {
+ d += encodeBlock(dst[d:], p)
+ }
+ }
+ return dst[:d]
+}
+
+// inputMargin is the minimum number of extra input bytes to keep, inside
+// encodeBlock's inner loop. On some architectures, this margin lets us
+// implement a fast path for emitLiteral, where the copy of short (<= 16 byte)
+// literals can be implemented as a single load to and store from a 16-byte
+// register. That literal's actual length can be as short as 1 byte, so this
+// can copy up to 15 bytes too much, but that's OK as subsequent iterations of
+// the encoding loop will fix up the copy overrun, and this inputMargin ensures
+// that we don't overrun the dst and src buffers.
+const inputMargin = 16 - 1
+
+// minNonLiteralBlockSize is the minimum size of the input to encodeBlock that
+// could be encoded with a copy tag. This is the minimum with respect to the
+// algorithm used by encodeBlock, not a minimum enforced by the file format.
+//
+// The encoded output must start with at least a 1 byte literal, as there are
+// no previous bytes to copy. A minimal (1 byte) copy after that, generated
+// from an emitCopy call in encodeBlock's main loop, would require at least
+// another inputMargin bytes, for the reason above: we want any emitLiteral
+// calls inside encodeBlock's main loop to use the fast path if possible, which
+// requires being able to overrun by inputMargin bytes. Thus,
+// minNonLiteralBlockSize equals 1 + 1 + inputMargin.
+//
+// The C++ code doesn't use this exact threshold, but it could, as discussed at
+// https://groups.google.com/d/topic/snappy-compression/oGbhsdIJSJ8/discussion
+// The difference between Go (2+inputMargin) and C++ (inputMargin) is purely an
+// optimization. It should not affect the encoded form. This is tested by
+// TestSameEncodingAsCppShortCopies.
+const minNonLiteralBlockSize = 1 + 1 + inputMargin
+
+// MaxEncodedLen returns the maximum length of a snappy block, given its
+// uncompressed length.
+//
+// It will return a negative value if srcLen is too large to encode.
+func MaxEncodedLen(srcLen int) int {
+ n := uint64(srcLen)
+ if n > 0xffffffff {
+ return -1
+ }
+ // Compressed data can be defined as:
+ // compressed := item* literal*
+ // item := literal* copy
+ //
+ // The trailing literal sequence has a space blowup of at most 62/60
+ // since a literal of length 60 needs one tag byte + one extra byte
+ // for length information.
+ //
+ // Item blowup is trickier to measure. Suppose the "copy" op copies
+ // 4 bytes of data. Because of a special check in the encoding code,
+ // we produce a 4-byte copy only if the offset is < 65536. Therefore
+ // the copy op takes 3 bytes to encode, and this type of item leads
+ // to at most the 62/60 blowup for representing literals.
+ //
+ // Suppose the "copy" op copies 5 bytes of data. If the offset is big
+ // enough, it will take 5 bytes to encode the copy op. Therefore the
+ // worst case here is a one-byte literal followed by a five-byte copy.
+ // That is, 6 bytes of input turn into 7 bytes of "compressed" data.
+ //
+ // This last factor dominates the blowup, so the final estimate is:
+ n = 32 + n + n/6
+ if n > 0xffffffff {
+ return -1
+ }
+ return int(n)
+}
+
+var errClosed = errors.New("snappy: Writer is closed")
+
+// NewWriter returns a new Writer that compresses to w.
+//
+// The Writer returned does not buffer writes. There is no need to Flush or
+// Close such a Writer.
+//
+// Deprecated: the Writer returned is not suitable for many small writes, only
+// for few large writes. Use NewBufferedWriter instead, which is efficient
+// regardless of the frequency and shape of the writes, and remember to Close
+// that Writer when done.
+func NewWriter(w io.Writer) *Writer {
+ return &Writer{
+ w: w,
+ obuf: make([]byte, obufLen),
+ }
+}
+
+// NewBufferedWriter returns a new Writer that compresses to w, using the
+// framing format described at
+// https://github.com/google/snappy/blob/master/framing_format.txt
+//
+// The Writer returned buffers writes. Users must call Close to guarantee all
+// data has been forwarded to the underlying io.Writer. They may also call
+// Flush zero or more times before calling Close.
+func NewBufferedWriter(w io.Writer) *Writer {
+ return &Writer{
+ w: w,
+ ibuf: make([]byte, 0, maxBlockSize),
+ obuf: make([]byte, obufLen),
+ }
+}
+
+// Writer is an io.Writer that can write Snappy-compressed bytes.
+type Writer struct {
+ w io.Writer
+ err error
+
+ // ibuf is a buffer for the incoming (uncompressed) bytes.
+ //
+ // Its use is optional. For backwards compatibility, Writers created by the
+ // NewWriter function have ibuf == nil, do not buffer incoming bytes, and
+ // therefore do not need to be Flush'ed or Close'd.
+ ibuf []byte
+
+ // obuf is a buffer for the outgoing (compressed) bytes.
+ obuf []byte
+
+ // wroteStreamHeader is whether we have written the stream header.
+ wroteStreamHeader bool
+}
+
+// Reset discards the writer's state and switches the Snappy writer to write to
+// w. This permits reusing a Writer rather than allocating a new one.
+func (w *Writer) Reset(writer io.Writer) {
+ w.w = writer
+ w.err = nil
+ if w.ibuf != nil {
+ w.ibuf = w.ibuf[:0]
+ }
+ w.wroteStreamHeader = false
+}
+
+// Write satisfies the io.Writer interface.
+func (w *Writer) Write(p []byte) (nRet int, errRet error) {
+ if w.ibuf == nil {
+ // Do not buffer incoming bytes. This does not perform or compress well
+ // if the caller of Writer.Write writes many small slices. This
+ // behavior is therefore deprecated, but still supported for backwards
+ // compatibility with code that doesn't explicitly Flush or Close.
+ return w.write(p)
+ }
+
+ // The remainder of this method is based on bufio.Writer.Write from the
+ // standard library.
+
+ for len(p) > (cap(w.ibuf)-len(w.ibuf)) && w.err == nil {
+ var n int
+ if len(w.ibuf) == 0 {
+ // Large write, empty buffer.
+ // Write directly from p to avoid copy.
+ n, _ = w.write(p)
+ } else {
+ n = copy(w.ibuf[len(w.ibuf):cap(w.ibuf)], p)
+ w.ibuf = w.ibuf[:len(w.ibuf)+n]
+ w.Flush()
+ }
+ nRet += n
+ p = p[n:]
+ }
+ if w.err != nil {
+ return nRet, w.err
+ }
+ n := copy(w.ibuf[len(w.ibuf):cap(w.ibuf)], p)
+ w.ibuf = w.ibuf[:len(w.ibuf)+n]
+ nRet += n
+ return nRet, nil
+}
+
+func (w *Writer) write(p []byte) (nRet int, errRet error) {
+ if w.err != nil {
+ return 0, w.err
+ }
+ for len(p) > 0 {
+ obufStart := len(magicChunk)
+ if !w.wroteStreamHeader {
+ w.wroteStreamHeader = true
+ copy(w.obuf, magicChunk)
+ obufStart = 0
+ }
+
+ var uncompressed []byte
+ if len(p) > maxBlockSize {
+ uncompressed, p = p[:maxBlockSize], p[maxBlockSize:]
+ } else {
+ uncompressed, p = p, nil
+ }
+ checksum := crc(uncompressed)
+
+ // Compress the buffer, discarding the result if the improvement
+ // isn't at least 12.5%.
+ compressed := Encode(w.obuf[obufHeaderLen:], uncompressed)
+ chunkType := uint8(chunkTypeCompressedData)
+ chunkLen := 4 + len(compressed)
+ obufEnd := obufHeaderLen + len(compressed)
+ if len(compressed) >= len(uncompressed)-len(uncompressed)/8 {
+ chunkType = chunkTypeUncompressedData
+ chunkLen = 4 + len(uncompressed)
+ obufEnd = obufHeaderLen
+ }
+
+ // Fill in the per-chunk header that comes before the body.
+ w.obuf[len(magicChunk)+0] = chunkType
+ w.obuf[len(magicChunk)+1] = uint8(chunkLen >> 0)
+ w.obuf[len(magicChunk)+2] = uint8(chunkLen >> 8)
+ w.obuf[len(magicChunk)+3] = uint8(chunkLen >> 16)
+ w.obuf[len(magicChunk)+4] = uint8(checksum >> 0)
+ w.obuf[len(magicChunk)+5] = uint8(checksum >> 8)
+ w.obuf[len(magicChunk)+6] = uint8(checksum >> 16)
+ w.obuf[len(magicChunk)+7] = uint8(checksum >> 24)
+
+ if _, err := w.w.Write(w.obuf[obufStart:obufEnd]); err != nil {
+ w.err = err
+ return nRet, err
+ }
+ if chunkType == chunkTypeUncompressedData {
+ if _, err := w.w.Write(uncompressed); err != nil {
+ w.err = err
+ return nRet, err
+ }
+ }
+ nRet += len(uncompressed)
+ }
+ return nRet, nil
+}
+
+// Flush flushes the Writer to its underlying io.Writer.
+func (w *Writer) Flush() error {
+ if w.err != nil {
+ return w.err
+ }
+ if len(w.ibuf) == 0 {
+ return nil
+ }
+ w.write(w.ibuf)
+ w.ibuf = w.ibuf[:0]
+ return w.err
+}
+
+// Close calls Flush and then closes the Writer.
+func (w *Writer) Close() error {
+ w.Flush()
+ ret := w.err
+ if w.err == nil {
+ w.err = errClosed
+ }
+ return ret
+}
diff --git a/vendor/github.com/golang/snappy/encode_amd64.go b/vendor/github.com/golang/snappy/encode_amd64.go
new file mode 100644
index 0000000..150d91b
--- /dev/null
+++ b/vendor/github.com/golang/snappy/encode_amd64.go
@@ -0,0 +1,29 @@
+// Copyright 2016 The Snappy-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.
+
+// +build !appengine
+// +build gc
+// +build !noasm
+
+package snappy
+
+// emitLiteral has the same semantics as in encode_other.go.
+//
+//go:noescape
+func emitLiteral(dst, lit []byte) int
+
+// emitCopy has the same semantics as in encode_other.go.
+//
+//go:noescape
+func emitCopy(dst []byte, offset, length int) int
+
+// extendMatch has the same semantics as in encode_other.go.
+//
+//go:noescape
+func extendMatch(src []byte, i, j int) int
+
+// encodeBlock has the same semantics as in encode_other.go.
+//
+//go:noescape
+func encodeBlock(dst, src []byte) (d int)
diff --git a/vendor/github.com/golang/snappy/encode_amd64.s b/vendor/github.com/golang/snappy/encode_amd64.s
new file mode 100644
index 0000000..adfd979
--- /dev/null
+++ b/vendor/github.com/golang/snappy/encode_amd64.s
@@ -0,0 +1,730 @@
+// Copyright 2016 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.
+
+// +build !appengine
+// +build gc
+// +build !noasm
+
+#include "textflag.h"
+
+// The XXX lines assemble on Go 1.4, 1.5 and 1.7, but not 1.6, due to a
+// Go toolchain regression. See https://github.com/golang/go/issues/15426 and
+// https://github.com/golang/snappy/issues/29
+//
+// As a workaround, the package was built with a known good assembler, and
+// those instructions were disassembled by "objdump -d" to yield the
+// 4e 0f b7 7c 5c 78 movzwq 0x78(%rsp,%r11,2),%r15
+// style comments, in AT&T asm syntax. Note that rsp here is a physical
+// register, not Go/asm's SP pseudo-register (see https://golang.org/doc/asm).
+// The instructions were then encoded as "BYTE $0x.." sequences, which assemble
+// fine on Go 1.6.
+
+// The asm code generally follows the pure Go code in encode_other.go, except
+// where marked with a "!!!".
+
+// ----------------------------------------------------------------------------
+
+// func emitLiteral(dst, lit []byte) int
+//
+// All local variables fit into registers. The register allocation:
+// - AX len(lit)
+// - BX n
+// - DX return value
+// - DI &dst[i]
+// - R10 &lit[0]
+//
+// The 24 bytes of stack space is to call runtime·memmove.
+//
+// The unusual register allocation of local variables, such as R10 for the
+// source pointer, matches the allocation used at the call site in encodeBlock,
+// which makes it easier to manually inline this function.
+TEXT ·emitLiteral(SB), NOSPLIT, $24-56
+ MOVQ dst_base+0(FP), DI
+ MOVQ lit_base+24(FP), R10
+ MOVQ lit_len+32(FP), AX
+ MOVQ AX, DX
+ MOVL AX, BX
+ SUBL $1, BX
+
+ CMPL BX, $60
+ JLT oneByte
+ CMPL BX, $256
+ JLT twoBytes
+
+threeBytes:
+ MOVB $0xf4, 0(DI)
+ MOVW BX, 1(DI)
+ ADDQ $3, DI
+ ADDQ $3, DX
+ JMP memmove
+
+twoBytes:
+ MOVB $0xf0, 0(DI)
+ MOVB BX, 1(DI)
+ ADDQ $2, DI
+ ADDQ $2, DX
+ JMP memmove
+
+oneByte:
+ SHLB $2, BX
+ MOVB BX, 0(DI)
+ ADDQ $1, DI
+ ADDQ $1, DX
+
+memmove:
+ MOVQ DX, ret+48(FP)
+
+ // copy(dst[i:], lit)
+ //
+ // This means calling runtime·memmove(&dst[i], &lit[0], len(lit)), so we push
+ // DI, R10 and AX as arguments.
+ MOVQ DI, 0(SP)
+ MOVQ R10, 8(SP)
+ MOVQ AX, 16(SP)
+ CALL runtime·memmove(SB)
+ RET
+
+// ----------------------------------------------------------------------------
+
+// func emitCopy(dst []byte, offset, length int) int
+//
+// All local variables fit into registers. The register allocation:
+// - AX length
+// - SI &dst[0]
+// - DI &dst[i]
+// - R11 offset
+//
+// The unusual register allocation of local variables, such as R11 for the
+// offset, matches the allocation used at the call site in encodeBlock, which
+// makes it easier to manually inline this function.
+TEXT ·emitCopy(SB), NOSPLIT, $0-48
+ MOVQ dst_base+0(FP), DI
+ MOVQ DI, SI
+ MOVQ offset+24(FP), R11
+ MOVQ length+32(FP), AX
+
+loop0:
+ // for length >= 68 { etc }
+ CMPL AX, $68
+ JLT step1
+
+ // Emit a length 64 copy, encoded as 3 bytes.
+ MOVB $0xfe, 0(DI)
+ MOVW R11, 1(DI)
+ ADDQ $3, DI
+ SUBL $64, AX
+ JMP loop0
+
+step1:
+ // if length > 64 { etc }
+ CMPL AX, $64
+ JLE step2
+
+ // Emit a length 60 copy, encoded as 3 bytes.
+ MOVB $0xee, 0(DI)
+ MOVW R11, 1(DI)
+ ADDQ $3, DI
+ SUBL $60, AX
+
+step2:
+ // if length >= 12 || offset >= 2048 { goto step3 }
+ CMPL AX, $12
+ JGE step3
+ CMPL R11, $2048
+ JGE step3
+
+ // Emit the remaining copy, encoded as 2 bytes.
+ MOVB R11, 1(DI)
+ SHRL $8, R11
+ SHLB $5, R11
+ SUBB $4, AX
+ SHLB $2, AX
+ ORB AX, R11
+ ORB $1, R11
+ MOVB R11, 0(DI)
+ ADDQ $2, DI
+
+ // Return the number of bytes written.
+ SUBQ SI, DI
+ MOVQ DI, ret+40(FP)
+ RET
+
+step3:
+ // Emit the remaining copy, encoded as 3 bytes.
+ SUBL $1, AX
+ SHLB $2, AX
+ ORB $2, AX
+ MOVB AX, 0(DI)
+ MOVW R11, 1(DI)
+ ADDQ $3, DI
+
+ // Return the number of bytes written.
+ SUBQ SI, DI
+ MOVQ DI, ret+40(FP)
+ RET
+
+// ----------------------------------------------------------------------------
+
+// func extendMatch(src []byte, i, j int) int
+//
+// All local variables fit into registers. The register allocation:
+// - DX &src[0]
+// - SI &src[j]
+// - R13 &src[len(src) - 8]
+// - R14 &src[len(src)]
+// - R15 &src[i]
+//
+// The unusual register allocation of local variables, such as R15 for a source
+// pointer, matches the allocation used at the call site in encodeBlock, which
+// makes it easier to manually inline this function.
+TEXT ·extendMatch(SB), NOSPLIT, $0-48
+ MOVQ src_base+0(FP), DX
+ MOVQ src_len+8(FP), R14
+ MOVQ i+24(FP), R15
+ MOVQ j+32(FP), SI
+ ADDQ DX, R14
+ ADDQ DX, R15
+ ADDQ DX, SI
+ MOVQ R14, R13
+ SUBQ $8, R13
+
+cmp8:
+ // As long as we are 8 or more bytes before the end of src, we can load and
+ // compare 8 bytes at a time. If those 8 bytes are equal, repeat.
+ CMPQ SI, R13
+ JA cmp1
+ MOVQ (R15), AX
+ MOVQ (SI), BX
+ CMPQ AX, BX
+ JNE bsf
+ ADDQ $8, R15
+ ADDQ $8, SI
+ JMP cmp8
+
+bsf:
+ // If those 8 bytes were not equal, XOR the two 8 byte values, and return
+ // the index of the first byte that differs. The BSF instruction finds the
+ // least significant 1 bit, the amd64 architecture is little-endian, and
+ // the shift by 3 converts a bit index to a byte index.
+ XORQ AX, BX
+ BSFQ BX, BX
+ SHRQ $3, BX
+ ADDQ BX, SI
+
+ // Convert from &src[ret] to ret.
+ SUBQ DX, SI
+ MOVQ SI, ret+40(FP)
+ RET
+
+cmp1:
+ // In src's tail, compare 1 byte at a time.
+ CMPQ SI, R14
+ JAE extendMatchEnd
+ MOVB (R15), AX
+ MOVB (SI), BX
+ CMPB AX, BX
+ JNE extendMatchEnd
+ ADDQ $1, R15
+ ADDQ $1, SI
+ JMP cmp1
+
+extendMatchEnd:
+ // Convert from &src[ret] to ret.
+ SUBQ DX, SI
+ MOVQ SI, ret+40(FP)
+ RET
+
+// ----------------------------------------------------------------------------
+
+// func encodeBlock(dst, src []byte) (d int)
+//
+// All local variables fit into registers, other than "var table". The register
+// allocation:
+// - AX . .
+// - BX . .
+// - CX 56 shift (note that amd64 shifts by non-immediates must use CX).
+// - DX 64 &src[0], tableSize
+// - SI 72 &src[s]
+// - DI 80 &dst[d]
+// - R9 88 sLimit
+// - R10 . &src[nextEmit]
+// - R11 96 prevHash, currHash, nextHash, offset
+// - R12 104 &src[base], skip
+// - R13 . &src[nextS], &src[len(src) - 8]
+// - R14 . len(src), bytesBetweenHashLookups, &src[len(src)], x
+// - R15 112 candidate
+//
+// The second column (56, 64, etc) is the stack offset to spill the registers
+// when calling other functions. We could pack this slightly tighter, but it's
+// simpler to have a dedicated spill map independent of the function called.
+//
+// "var table [maxTableSize]uint16" takes up 32768 bytes of stack space. An
+// extra 56 bytes, to call other functions, and an extra 64 bytes, to spill
+// local variables (registers) during calls gives 32768 + 56 + 64 = 32888.
+TEXT ·encodeBlock(SB), 0, $32888-56
+ MOVQ dst_base+0(FP), DI
+ MOVQ src_base+24(FP), SI
+ MOVQ src_len+32(FP), R14
+
+ // shift, tableSize := uint32(32-8), 1<<8
+ MOVQ $24, CX
+ MOVQ $256, DX
+
+calcShift:
+ // for ; tableSize < maxTableSize && tableSize < len(src); tableSize *= 2 {
+ // shift--
+ // }
+ CMPQ DX, $16384
+ JGE varTable
+ CMPQ DX, R14
+ JGE varTable
+ SUBQ $1, CX
+ SHLQ $1, DX
+ JMP calcShift
+
+varTable:
+ // var table [maxTableSize]uint16
+ //
+ // In the asm code, unlike the Go code, we can zero-initialize only the
+ // first tableSize elements. Each uint16 element is 2 bytes and each MOVOU
+ // writes 16 bytes, so we can do only tableSize/8 writes instead of the
+ // 2048 writes that would zero-initialize all of table's 32768 bytes.
+ SHRQ $3, DX
+ LEAQ table-32768(SP), BX
+ PXOR X0, X0
+
+memclr:
+ MOVOU X0, 0(BX)
+ ADDQ $16, BX
+ SUBQ $1, DX
+ JNZ memclr
+
+ // !!! DX = &src[0]
+ MOVQ SI, DX
+
+ // sLimit := len(src) - inputMargin
+ MOVQ R14, R9
+ SUBQ $15, R9
+
+ // !!! Pre-emptively spill CX, DX and R9 to the stack. Their values don't
+ // change for the rest of the function.
+ MOVQ CX, 56(SP)
+ MOVQ DX, 64(SP)
+ MOVQ R9, 88(SP)
+
+ // nextEmit := 0
+ MOVQ DX, R10
+
+ // s := 1
+ ADDQ $1, SI
+
+ // nextHash := hash(load32(src, s), shift)
+ MOVL 0(SI), R11
+ IMULL $0x1e35a7bd, R11
+ SHRL CX, R11
+
+outer:
+ // for { etc }
+
+ // skip := 32
+ MOVQ $32, R12
+
+ // nextS := s
+ MOVQ SI, R13
+
+ // candidate := 0
+ MOVQ $0, R15
+
+inner0:
+ // for { etc }
+
+ // s := nextS
+ MOVQ R13, SI
+
+ // bytesBetweenHashLookups := skip >> 5
+ MOVQ R12, R14
+ SHRQ $5, R14
+
+ // nextS = s + bytesBetweenHashLookups
+ ADDQ R14, R13
+
+ // skip += bytesBetweenHashLookups
+ ADDQ R14, R12
+
+ // if nextS > sLimit { goto emitRemainder }
+ MOVQ R13, AX
+ SUBQ DX, AX
+ CMPQ AX, R9
+ JA emitRemainder
+
+ // candidate = int(table[nextHash])
+ // XXX: MOVWQZX table-32768(SP)(R11*2), R15
+ // XXX: 4e 0f b7 7c 5c 78 movzwq 0x78(%rsp,%r11,2),%r15
+ BYTE $0x4e
+ BYTE $0x0f
+ BYTE $0xb7
+ BYTE $0x7c
+ BYTE $0x5c
+ BYTE $0x78
+
+ // table[nextHash] = uint16(s)
+ MOVQ SI, AX
+ SUBQ DX, AX
+
+ // XXX: MOVW AX, table-32768(SP)(R11*2)
+ // XXX: 66 42 89 44 5c 78 mov %ax,0x78(%rsp,%r11,2)
+ BYTE $0x66
+ BYTE $0x42
+ BYTE $0x89
+ BYTE $0x44
+ BYTE $0x5c
+ BYTE $0x78
+
+ // nextHash = hash(load32(src, nextS), shift)
+ MOVL 0(R13), R11
+ IMULL $0x1e35a7bd, R11
+ SHRL CX, R11
+
+ // if load32(src, s) != load32(src, candidate) { continue } break
+ MOVL 0(SI), AX
+ MOVL (DX)(R15*1), BX
+ CMPL AX, BX
+ JNE inner0
+
+fourByteMatch:
+ // As per the encode_other.go code:
+ //
+ // A 4-byte match has been found. We'll later see etc.
+
+ // !!! Jump to a fast path for short (<= 16 byte) literals. See the comment
+ // on inputMargin in encode.go.
+ MOVQ SI, AX
+ SUBQ R10, AX
+ CMPQ AX, $16
+ JLE emitLiteralFastPath
+
+ // ----------------------------------------
+ // Begin inline of the emitLiteral call.
+ //
+ // d += emitLiteral(dst[d:], src[nextEmit:s])
+
+ MOVL AX, BX
+ SUBL $1, BX
+
+ CMPL BX, $60
+ JLT inlineEmitLiteralOneByte
+ CMPL BX, $256
+ JLT inlineEmitLiteralTwoBytes
+
+inlineEmitLiteralThreeBytes:
+ MOVB $0xf4, 0(DI)
+ MOVW BX, 1(DI)
+ ADDQ $3, DI
+ JMP inlineEmitLiteralMemmove
+
+inlineEmitLiteralTwoBytes:
+ MOVB $0xf0, 0(DI)
+ MOVB BX, 1(DI)
+ ADDQ $2, DI
+ JMP inlineEmitLiteralMemmove
+
+inlineEmitLiteralOneByte:
+ SHLB $2, BX
+ MOVB BX, 0(DI)
+ ADDQ $1, DI
+
+inlineEmitLiteralMemmove:
+ // Spill local variables (registers) onto the stack; call; unspill.
+ //
+ // copy(dst[i:], lit)
+ //
+ // This means calling runtime·memmove(&dst[i], &lit[0], len(lit)), so we push
+ // DI, R10 and AX as arguments.
+ MOVQ DI, 0(SP)
+ MOVQ R10, 8(SP)
+ MOVQ AX, 16(SP)
+ ADDQ AX, DI // Finish the "d +=" part of "d += emitLiteral(etc)".
+ MOVQ SI, 72(SP)
+ MOVQ DI, 80(SP)
+ MOVQ R15, 112(SP)
+ CALL runtime·memmove(SB)
+ MOVQ 56(SP), CX
+ MOVQ 64(SP), DX
+ MOVQ 72(SP), SI
+ MOVQ 80(SP), DI
+ MOVQ 88(SP), R9
+ MOVQ 112(SP), R15
+ JMP inner1
+
+inlineEmitLiteralEnd:
+ // End inline of the emitLiteral call.
+ // ----------------------------------------
+
+emitLiteralFastPath:
+ // !!! Emit the 1-byte encoding "uint8(len(lit)-1)<<2".
+ MOVB AX, BX
+ SUBB $1, BX
+ SHLB $2, BX
+ MOVB BX, (DI)
+ ADDQ $1, DI
+
+ // !!! Implement the copy from lit to dst as a 16-byte load and store.
+ // (Encode's documentation says that dst and src must not overlap.)
+ //
+ // This always copies 16 bytes, instead of only len(lit) bytes, but that's
+ // OK. Subsequent iterations will fix up the overrun.
+ //
+ // Note that on amd64, it is legal and cheap to issue unaligned 8-byte or
+ // 16-byte loads and stores. This technique probably wouldn't be as
+ // effective on architectures that are fussier about alignment.
+ MOVOU 0(R10), X0
+ MOVOU X0, 0(DI)
+ ADDQ AX, DI
+
+inner1:
+ // for { etc }
+
+ // base := s
+ MOVQ SI, R12
+
+ // !!! offset := base - candidate
+ MOVQ R12, R11
+ SUBQ R15, R11
+ SUBQ DX, R11
+
+ // ----------------------------------------
+ // Begin inline of the extendMatch call.
+ //
+ // s = extendMatch(src, candidate+4, s+4)
+
+ // !!! R14 = &src[len(src)]
+ MOVQ src_len+32(FP), R14
+ ADDQ DX, R14
+
+ // !!! R13 = &src[len(src) - 8]
+ MOVQ R14, R13
+ SUBQ $8, R13
+
+ // !!! R15 = &src[candidate + 4]
+ ADDQ $4, R15
+ ADDQ DX, R15
+
+ // !!! s += 4
+ ADDQ $4, SI
+
+inlineExtendMatchCmp8:
+ // As long as we are 8 or more bytes before the end of src, we can load and
+ // compare 8 bytes at a time. If those 8 bytes are equal, repeat.
+ CMPQ SI, R13
+ JA inlineExtendMatchCmp1
+ MOVQ (R15), AX
+ MOVQ (SI), BX
+ CMPQ AX, BX
+ JNE inlineExtendMatchBSF
+ ADDQ $8, R15
+ ADDQ $8, SI
+ JMP inlineExtendMatchCmp8
+
+inlineExtendMatchBSF:
+ // If those 8 bytes were not equal, XOR the two 8 byte values, and return
+ // the index of the first byte that differs. The BSF instruction finds the
+ // least significant 1 bit, the amd64 architecture is little-endian, and
+ // the shift by 3 converts a bit index to a byte index.
+ XORQ AX, BX
+ BSFQ BX, BX
+ SHRQ $3, BX
+ ADDQ BX, SI
+ JMP inlineExtendMatchEnd
+
+inlineExtendMatchCmp1:
+ // In src's tail, compare 1 byte at a time.
+ CMPQ SI, R14
+ JAE inlineExtendMatchEnd
+ MOVB (R15), AX
+ MOVB (SI), BX
+ CMPB AX, BX
+ JNE inlineExtendMatchEnd
+ ADDQ $1, R15
+ ADDQ $1, SI
+ JMP inlineExtendMatchCmp1
+
+inlineExtendMatchEnd:
+ // End inline of the extendMatch call.
+ // ----------------------------------------
+
+ // ----------------------------------------
+ // Begin inline of the emitCopy call.
+ //
+ // d += emitCopy(dst[d:], base-candidate, s-base)
+
+ // !!! length := s - base
+ MOVQ SI, AX
+ SUBQ R12, AX
+
+inlineEmitCopyLoop0:
+ // for length >= 68 { etc }
+ CMPL AX, $68
+ JLT inlineEmitCopyStep1
+
+ // Emit a length 64 copy, encoded as 3 bytes.
+ MOVB $0xfe, 0(DI)
+ MOVW R11, 1(DI)
+ ADDQ $3, DI
+ SUBL $64, AX
+ JMP inlineEmitCopyLoop0
+
+inlineEmitCopyStep1:
+ // if length > 64 { etc }
+ CMPL AX, $64
+ JLE inlineEmitCopyStep2
+
+ // Emit a length 60 copy, encoded as 3 bytes.
+ MOVB $0xee, 0(DI)
+ MOVW R11, 1(DI)
+ ADDQ $3, DI
+ SUBL $60, AX
+
+inlineEmitCopyStep2:
+ // if length >= 12 || offset >= 2048 { goto inlineEmitCopyStep3 }
+ CMPL AX, $12
+ JGE inlineEmitCopyStep3
+ CMPL R11, $2048
+ JGE inlineEmitCopyStep3
+
+ // Emit the remaining copy, encoded as 2 bytes.
+ MOVB R11, 1(DI)
+ SHRL $8, R11
+ SHLB $5, R11
+ SUBB $4, AX
+ SHLB $2, AX
+ ORB AX, R11
+ ORB $1, R11
+ MOVB R11, 0(DI)
+ ADDQ $2, DI
+ JMP inlineEmitCopyEnd
+
+inlineEmitCopyStep3:
+ // Emit the remaining copy, encoded as 3 bytes.
+ SUBL $1, AX
+ SHLB $2, AX
+ ORB $2, AX
+ MOVB AX, 0(DI)
+ MOVW R11, 1(DI)
+ ADDQ $3, DI
+
+inlineEmitCopyEnd:
+ // End inline of the emitCopy call.
+ // ----------------------------------------
+
+ // nextEmit = s
+ MOVQ SI, R10
+
+ // if s >= sLimit { goto emitRemainder }
+ MOVQ SI, AX
+ SUBQ DX, AX
+ CMPQ AX, R9
+ JAE emitRemainder
+
+ // As per the encode_other.go code:
+ //
+ // We could immediately etc.
+
+ // x := load64(src, s-1)
+ MOVQ -1(SI), R14
+
+ // prevHash := hash(uint32(x>>0), shift)
+ MOVL R14, R11
+ IMULL $0x1e35a7bd, R11
+ SHRL CX, R11
+
+ // table[prevHash] = uint16(s-1)
+ MOVQ SI, AX
+ SUBQ DX, AX
+ SUBQ $1, AX
+
+ // XXX: MOVW AX, table-32768(SP)(R11*2)
+ // XXX: 66 42 89 44 5c 78 mov %ax,0x78(%rsp,%r11,2)
+ BYTE $0x66
+ BYTE $0x42
+ BYTE $0x89
+ BYTE $0x44
+ BYTE $0x5c
+ BYTE $0x78
+
+ // currHash := hash(uint32(x>>8), shift)
+ SHRQ $8, R14
+ MOVL R14, R11
+ IMULL $0x1e35a7bd, R11
+ SHRL CX, R11
+
+ // candidate = int(table[currHash])
+ // XXX: MOVWQZX table-32768(SP)(R11*2), R15
+ // XXX: 4e 0f b7 7c 5c 78 movzwq 0x78(%rsp,%r11,2),%r15
+ BYTE $0x4e
+ BYTE $0x0f
+ BYTE $0xb7
+ BYTE $0x7c
+ BYTE $0x5c
+ BYTE $0x78
+
+ // table[currHash] = uint16(s)
+ ADDQ $1, AX
+
+ // XXX: MOVW AX, table-32768(SP)(R11*2)
+ // XXX: 66 42 89 44 5c 78 mov %ax,0x78(%rsp,%r11,2)
+ BYTE $0x66
+ BYTE $0x42
+ BYTE $0x89
+ BYTE $0x44
+ BYTE $0x5c
+ BYTE $0x78
+
+ // if uint32(x>>8) == load32(src, candidate) { continue }
+ MOVL (DX)(R15*1), BX
+ CMPL R14, BX
+ JEQ inner1
+
+ // nextHash = hash(uint32(x>>16), shift)
+ SHRQ $8, R14
+ MOVL R14, R11
+ IMULL $0x1e35a7bd, R11
+ SHRL CX, R11
+
+ // s++
+ ADDQ $1, SI
+
+ // break out of the inner1 for loop, i.e. continue the outer loop.
+ JMP outer
+
+emitRemainder:
+ // if nextEmit < len(src) { etc }
+ MOVQ src_len+32(FP), AX
+ ADDQ DX, AX
+ CMPQ R10, AX
+ JEQ encodeBlockEnd
+
+ // d += emitLiteral(dst[d:], src[nextEmit:])
+ //
+ // Push args.
+ MOVQ DI, 0(SP)
+ MOVQ $0, 8(SP) // Unnecessary, as the callee ignores it, but conservative.
+ MOVQ $0, 16(SP) // Unnecessary, as the callee ignores it, but conservative.
+ MOVQ R10, 24(SP)
+ SUBQ R10, AX
+ MOVQ AX, 32(SP)
+ MOVQ AX, 40(SP) // Unnecessary, as the callee ignores it, but conservative.
+
+ // Spill local variables (registers) onto the stack; call; unspill.
+ MOVQ DI, 80(SP)
+ CALL ·emitLiteral(SB)
+ MOVQ 80(SP), DI
+
+ // Finish the "d +=" part of "d += emitLiteral(etc)".
+ ADDQ 48(SP), DI
+
+encodeBlockEnd:
+ MOVQ dst_base+0(FP), AX
+ SUBQ AX, DI
+ MOVQ DI, d+48(FP)
+ RET
diff --git a/vendor/github.com/golang/snappy/snappy.go b/vendor/github.com/golang/snappy/snappy.go
new file mode 100644
index 0000000..0cf5e37
--- /dev/null
+++ b/vendor/github.com/golang/snappy/snappy.go
@@ -0,0 +1,87 @@
+// Copyright 2011 The Snappy-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 snappy implements the snappy block-based compression format.
+// It aims for very high speeds and reasonable compression.
+//
+// The C++ snappy implementation is at https://github.com/google/snappy
+package snappy // import "github.com/golang/snappy"
+
+import (
+ "hash/crc32"
+)
+
+/*
+Each encoded block begins with the varint-encoded length of the decoded data,
+followed by a sequence of chunks. Chunks begin and end on byte boundaries. The
+first byte of each chunk is broken into its 2 least and 6 most significant bits
+called l and m: l ranges in [0, 4) and m ranges in [0, 64). l is the chunk tag.
+Zero means a literal tag. All other values mean a copy tag.
+
+For literal tags:
+ - If m < 60, the next 1 + m bytes are literal bytes.
+ - Otherwise, let n be the little-endian unsigned integer denoted by the next
+ m - 59 bytes. The next 1 + n bytes after that are literal bytes.
+
+For copy tags, length bytes are copied from offset bytes ago, in the style of
+Lempel-Ziv compression algorithms. In particular:
+ - For l == 1, the offset ranges in [0, 1<<11) and the length in [4, 12).
+ The length is 4 + the low 3 bits of m. The high 3 bits of m form bits 8-10
+ of the offset. The next byte is bits 0-7 of the offset.
+ - For l == 2, the offset ranges in [0, 1<<16) and the length in [1, 65).
+ The length is 1 + m. The offset is the little-endian unsigned integer
+ denoted by the next 2 bytes.
+ - For l == 3, this tag is a legacy format that is no longer issued by most
+ encoders. Nonetheless, the offset ranges in [0, 1<<32) and the length in
+ [1, 65). The length is 1 + m. The offset is the little-endian unsigned
+ integer denoted by the next 4 bytes.
+*/
+const (
+ tagLiteral = 0x00
+ tagCopy1 = 0x01
+ tagCopy2 = 0x02
+ tagCopy4 = 0x03
+)
+
+const (
+ checksumSize = 4
+ chunkHeaderSize = 4
+ magicChunk = "\xff\x06\x00\x00" + magicBody
+ magicBody = "sNaPpY"
+
+ // maxBlockSize is the maximum size of the input to encodeBlock. It is not
+ // part of the wire format per se, but some parts of the encoder assume
+ // that an offset fits into a uint16.
+ //
+ // Also, for the framing format (Writer type instead of Encode function),
+ // https://github.com/google/snappy/blob/master/framing_format.txt says
+ // that "the uncompressed data in a chunk must be no longer than 65536
+ // bytes".
+ maxBlockSize = 65536
+
+ // maxEncodedLenOfMaxBlockSize equals MaxEncodedLen(maxBlockSize), but is
+ // hard coded to be a const instead of a variable, so that obufLen can also
+ // be a const. Their equivalence is confirmed by
+ // TestMaxEncodedLenOfMaxBlockSize.
+ maxEncodedLenOfMaxBlockSize = 76490
+
+ obufHeaderLen = len(magicChunk) + checksumSize + chunkHeaderSize
+ obufLen = obufHeaderLen + maxEncodedLenOfMaxBlockSize
+)
+
+const (
+ chunkTypeCompressedData = 0x00
+ chunkTypeUncompressedData = 0x01
+ chunkTypePadding = 0xfe
+ chunkTypeStreamIdentifier = 0xff
+)
+
+var crcTable = crc32.MakeTable(crc32.Castagnoli)
+
+// crc implements the checksum specified in section 3 of
+// https://github.com/google/snappy/blob/master/framing_format.txt
+func crc(b []byte) uint32 {
+ c := crc32.Update(0, crcTable, b)
+ return uint32(c>>15|c<<17) + 0xa282ead8
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-18 13:28:47 +0000