Rename funnybase and add more serializations.

common/funnybase/funnybase.go

Index: common/funnybase/funnybase.go
diff --git a/common/funnybase/funnybase.go b/common/funnybase/funnybase.go
deleted file mode 100644
index eb5e9e80a99e0e77ed1c1ffdcd997e78e240c971..0000000000000000000000000000000000000000
--- a/common/funnybase/funnybase.go
+++ /dev/null
@@ -1,271 +0,0 @@
-// Copyright 2015 The Chromium 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 funnybase provides a varint-like signed integer encoding scheme which
-// has the property that the encoded integers can be compared with unordered
-// byte comparisons and they will sort correctly.
-//
-// It's less efficient on average than varint for small numbers (it has
-// a minimum encoded size of 2 bytes), but is more efficient for large numbers
-// (it has a maximum encoded size of 9 bytes for a 64 bit int).
-//
-// The scheme works like:
-//   * given an 2's compliment value V
-//   * extract the sign (S) and magnitude (M) of V
-//   * Find the position of the highest bit (P), minus 1.
-//   * write (bits):
-//     * SPPPPPPP MMMMMMMM MM000000
-//     * S is 1
-//     * P's are the log2(M)-1
-//     * M's are the magnitude of V
-//     * 0's are padding
-//   * Additionally, if the number is negative, invert the bits of all the bytes
-//     (e.g. XOR 0xFF). This makes the sign bit S 0 for negative numbers, and
-//     makes the ordering of the numbers correct when compared bytewise.
-package funnybase
-
-import (
-	"bytes"
-	"errors"
-	"io"
-	"math"
-)
-
-// MaxFunnyBaseLenN is the maximum length of a funnybase-encoded N-bit integer.
-const (
-	MaxFunnyBaseLen16 = 3
-	MaxFunnyBaseLen32 = 5
-	MaxFunnyBaseLen64 = 9
-)
-
-// ErrOutOfBounds is panic'd when using Put/PutUint with a buffer that's
-// not large enough to hold the value being encoded.
-var ErrOutOfBounds = errors.New("funnybase: buffer was too small")
-
-// ErrOverflow is returned when reading an number which is too large for the
-// destination type (either uint64 or int64)
-var ErrOverflow = errors.New("funnybase: varint overflows")
-
-// ErrUnderflow is returned when reading an number which is too small for the
-// destination type (either uint64 or int64)
-var ErrUnderflow = errors.New("funnybase: uvarint underflows")
-
-var paddingMasks = [...]uint64{
-	0xFFFFFFFF00000000,
-	0xFFFF0000,
-	0xFF00,
-	0xF0,
-	0xC,
-	0x2,
-	0x1,
-}
-
-// Calculate the log2 of the unsigned value v.
-//
-// This is used to find the position of the highest-set bit in v.
-//
-// from https://graphics.stanford.edu/~seander/bithacks.html#IntegerLog
-// 32 bit implementation extended to 64 bits
-func uint64Log2(v uint64) uint {
-	log := uint(0)
-	for i, m := range paddingMasks {
-		if v&m != 0 {
-			shift := uint(1<<uint(len(paddingMasks)-2)) >> uint(i)
-			v >>= shift
-			log |= shift
-		}
-	}
-	return log + 1
-}
-
-// Put encodes an int64 into buf and returns the number of bytes written.
-// If the buffer's length is too small, Put will panic.
-func Put(buf []byte, val int64) uint {
-	r, err := write(bytes.NewBuffer(buf[:0]), val, uint(len(buf)))
-	if err != nil {
-		panic(err)
-	}
-	return r
-}
-
-// Write val as a funnybase to the ByteWriter. Will only return an error if
-// the underlying ByteWriter returns an error.
-func Write(w io.ByteWriter, val int64) error {
-	_, err := write(w, val, MaxFunnyBaseLen64)
-	return err
-}
-
-func write(w io.ByteWriter, val int64, byteLimit uint) (uint, error) {
-	var inv byte
-	if val < 0 {
-		inv = 0xff
-	}
-	mag := uint64(val)
-	if inv != 0 {
-		mag = -mag
-	}
-	return writeSignMag(w, mag, inv, byteLimit)
-}
-
-// PutUint encodes an int64 into buf and returns the number of bytes written.
-// If the buffer's length is too small, Put will panic.
-func PutUint(buf []byte, mag uint64) uint {
-	r, err := writeSignMag(bytes.NewBuffer(buf[:0]), mag, 0, uint(len(buf)))
-	if err != nil {
-		panic(err)
-	}
-	return r
-}
-
-// WriteUint writes mag to the ByteWriter. Will only return an error if the
-// underlying ByteWriter returns an error.
-func WriteUint(w io.ByteWriter, mag uint64) error {
-	_, err := writeSignMag(w, mag, 0, MaxFunnyBaseLen64)
-	return err
-}
-
-// Get decodes a funnybase-encoded number from a byte slice. Returns
-// the decoded value as well as the number of bytes read. If an error
-// occurs, the value is 0, and n will be:
-//
-//  n == 0: buf too small
-//  n == -1: value overflows int64
-//  n == -2: value underflows int64
-func Get(b []byte) (r int64, n int) {
-	buf := bytes.NewBuffer(b)
-	r, err := Read(buf)
-	switch err {
-	case ErrOverflow:
-		return 0, -1
-	case ErrUnderflow:
-		return 0, -2
-	case io.EOF:
-		return 0, 0
-	}
-	n = len(b) - buf.Len()
-	return
-}
-
-// GetUint decodes a funnybase-encoded number from a byte slice. Returns
-// the decoded value as well as the number of bytes read. If an error
-// occurs, the value is 0, and n will be:
-//
-//  n == 0: buf too small
-//  n == -1: value overflows uint64
-//  n == -2: value underflows uint64
-func GetUint(b []byte) (mag uint64, n int) {
-	buf := bytes.NewBuffer(b)
-	mag, err := ReadUint(buf)
-	switch err {
-	case ErrOverflow:
-		return 0, -1
-	case ErrUnderflow:
-		return 0, -2
-	case io.EOF:
-		return 0, 0
-	}
-	n = len(b) - buf.Len()
-	return
-}
-
-// Read decodes a funnybase-encoded number from a ByteReader. It
-// returns err{Over,Under}flow if the number is out of bounds. It may also
-// return an error if the ByteReader returns an error.
-func Read(r io.ByteReader) (int64, error) {
-	pos, sigs, mag, err := readSignMag(r)
-	if err != nil {
-		return 0, err
-	}
-	if pos {
-		if sigs > 63 {
-			return 0, ErrOverflow
-		}
-		return int64(mag), nil
-	}
-	if mag > uint64(-math.MinInt64) {
-		return 0, ErrUnderflow
-	}
-	return int64(-mag), nil
-}
-
-// ReadUint decodes a funnybase-encoded positive number from a ByteReader.  It
-// returns err{Over,Under}flow if the number is out of bounds. It may also
-// return an error if the ByteReader returns an error.
-func ReadUint(r io.ByteReader) (uint64, error) {
-	pos, _, mag, err := readSignMag(r)
-	if err != nil {
-		return 0, err
-	}
-	if !pos {
-		return 0, ErrUnderflow
-	}
-	return mag, err
-}
-
-func writeSignMag(w io.ByteWriter, mag uint64, inv byte, byteLimit uint) (i uint, err error) {
-	sigs := uint64Log2(mag)
-
-	wb := func(b byte) error {
-		i++
-		if i > byteLimit {
-			return ErrOutOfBounds
-		}
-		return w.WriteByte(b)
-	}
-
-	if err = wb(byte(0x80|(sigs-1)) ^ inv); err != nil {
-		return
-	}
-
-	for sigs > 8 {
-		sigs -= 8
-
-		if err = wb(byte(mag>>sigs) ^ inv); err != nil {
-			return
-		}
-	}
-	if sigs != 0 {
-		if err = wb(byte(mag<<(8-sigs)) ^ inv); err != nil {
-			return
-		}
-	}
-
-	return
-}
-
-func readSignMag(r io.ByteReader) (positive bool, sigs uint, mag uint64, err error) {
-	var inv byte
-
-	b0, err := r.ReadByte()
-	if err != nil {
-		return
-	}
-	positive = true
-	if b0&0x80 == 0 {
-		positive = false
-		inv = 0xff
-	}
-
-	sigs = uint((b0^inv)&0x7f) + 1
-	if sigs > 64 {
-		err = ErrOverflow
-		return
-	}
-
-	n := int((sigs+7)>>3) + 1
-
-	var b byte
-	shift := uint(64 - 8)
-	for i := 1; i < n; i++ {
-		b, err = r.ReadByte()
-		if err != nil {
-			return
-		}
-		mag |= uint64(b^inv) << shift
-		shift -= 8
-	}
-	mag >>= 64 - sigs
-
-	return
-}