uquic/utils/utils.go

package utils

import (
	"bytes"
	"io"
)

// ReadUintN reads N bytes
// ToDo: add tests
func ReadUintN(b io.ByteReader, length uint8) (uint64, error) {
	var res uint64
	for i := uint8(0); i < length; i++ {
		bt, err := b.ReadByte()
		if err != nil {
			return 0, err
		}
		res ^= uint64(bt) << (i * 8)
	}
	return res, nil
}

// ReadUint32 reads a uint32
func ReadUint32(b io.ByteReader) (uint32, error) {
	var b1, b2, b3, b4 uint8
	var err error
	if b1, err = b.ReadByte(); err != nil {
		return 0, err
	}
	if b2, err = b.ReadByte(); err != nil {
		return 0, err
	}
	if b3, err = b.ReadByte(); err != nil {
		return 0, err
	}
	if b4, err = b.ReadByte(); err != nil {
		return 0, err
	}
	return uint32(b1) + uint32(b2)<<8 + uint32(b3)<<16 + uint32(b4)<<24, nil
}

// ReadUint16 reads a uint16
func ReadUint16(b io.ByteReader) (uint16, error) {
	var b1, b2 uint8
	var err error
	if b1, err = b.ReadByte(); err != nil {
		return 0, err
	}
	if b2, err = b.ReadByte(); err != nil {
		return 0, err
	}
	return uint16(b1) + uint16(b2)<<8, nil
}

// WriteUint64 writes a uint64
func WriteUint64(b *bytes.Buffer, i uint64) {
	b.WriteByte(uint8(i & 0xff))
	b.WriteByte(uint8((i >> 8) & 0xff))
	b.WriteByte(uint8((i >> 16) & 0xff))
	b.WriteByte(uint8((i >> 24) & 0xff))
	b.WriteByte(uint8((i >> 32) & 0xff))
	b.WriteByte(uint8((i >> 40) & 0xff))
	b.WriteByte(uint8((i >> 48) & 0xff))
	b.WriteByte(uint8(i >> 56))
}

// WriteUint32 writes a uint32
func WriteUint32(b *bytes.Buffer, i uint32) {
	b.WriteByte(uint8(i & 0xff))
	b.WriteByte(uint8((i >> 8) & 0xff))
	b.WriteByte(uint8((i >> 16) & 0xff))
	b.WriteByte(uint8((i >> 24) & 0xff))
}

// WriteUint16 writes a uint16
func WriteUint16(b *bytes.Buffer, i uint16) {
	b.WriteByte(uint8(i & 0xff))
	b.WriteByte(uint8((i >> 8) & 0xff))
}

// Max returns the maximum of two Ints
func Max(a, b int) int {
	if a < b {
		return b
	}
	return a
}

// Min returns the minimum of two Ints
func Min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

// Uint32Slice attaches the methods of sort.Interface to []uint32, sorting in increasing order.
type Uint32Slice []uint32

func (s Uint32Slice) Len() int           { return len(s) }
func (s Uint32Slice) Less(i, j int) bool { return s[i] < s[j] }
func (s Uint32Slice) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }