134 lines
2.8 KiB
Go
134 lines
2.8 KiB
Go
package common
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import (
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"bytes"
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"encoding/binary"
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"io"
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"log"
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)
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// StreamReader allows you to read data from a byte array in various formats
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type StreamReader struct {
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data []byte
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position uint64
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}
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// CreateStreamReader creates an instance of the stream reader
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func CreateStreamReader(source []byte) *StreamReader {
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result := &StreamReader{
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data: source,
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position: 0,
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}
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return result
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}
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// GetPosition returns the current stream position
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func (v *StreamReader) GetPosition() uint64 {
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return v.position
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}
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// GetSize returns the total size of the stream in bytes
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func (v *StreamReader) GetSize() uint64 {
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return uint64(len(v.data))
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}
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// GetByte returns a byte from the stream
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func (v *StreamReader) GetByte() byte {
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result := v.data[v.position]
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v.position++
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return result
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}
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// GetUInt16 returns a uint16 word from the stream
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func (v *StreamReader) GetUInt16() uint16 {
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result := uint16(v.data[v.position])
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result += uint16(v.data[v.position+1]) << 8
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v.position += 2
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return result
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}
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// GetInt16 returns a int16 word from the stream
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func (v *StreamReader) GetInt16() int16 {
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var result int16
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err := binary.Read(bytes.NewReader([]byte{v.data[v.position], v.data[v.position+1]}), binary.LittleEndian, &result)
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if err != nil {
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log.Panic(err)
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}
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v.position += 2
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return result
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}
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func (v *StreamReader) SetPosition(newPosition uint64) {
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v.position = newPosition
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}
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// GetUInt32 returns a uint32 word from the stream
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func (v *StreamReader) GetUInt32() uint32 {
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var result uint32
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err := binary.Read(bytes.NewReader(
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[]byte{
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v.data[v.position],
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v.data[v.position+1],
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v.data[v.position+2],
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v.data[v.position+3],
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}), binary.LittleEndian, &result)
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if err != nil {
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log.Panic(err)
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}
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v.position += 4
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return result
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}
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// GetInt32 returns an int32 word from the stream
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func (v *StreamReader) GetInt32() int32 {
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var result int32
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err := binary.Read(bytes.NewReader(
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[]byte{
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v.data[v.position],
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v.data[v.position+1],
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v.data[v.position+2],
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v.data[v.position+3],
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}), binary.LittleEndian, &result)
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if err != nil {
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log.Panic(err)
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}
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v.position += 4
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return result
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}
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// ReadByte implements io.ByteReader
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func (v *StreamReader) ReadByte() (byte, error) {
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return v.GetByte(), nil
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}
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// ReadBytes reads multiple bytes
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func (v *StreamReader) ReadBytes(count int) ([]byte, error) {
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result := make([]byte, count)
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for i := 0; i < count; i++ {
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result[i] = v.GetByte()
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}
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return result, nil
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}
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func (v *StreamReader) SkipBytes(count int) {
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v.position += uint64(count)
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}
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// Read implements io.Reader
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func (v *StreamReader) Read(p []byte) (n int, err error) {
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streamLength := v.GetSize()
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for i := 0; ; i++ {
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if v.GetPosition() >= streamLength {
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return i, io.EOF
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}
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if i >= len(p) {
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return i, nil
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}
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p[i] = v.GetByte()
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}
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}
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func (v *StreamReader) Eof() bool {
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return v.position >= uint64(len(v.data))
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}
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