166 lines
3.5 KiB
Go
166 lines
3.5 KiB
Go
package d2datautils
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import (
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"io"
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)
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const (
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bytesPerInt16 = 2
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bytesPerInt32 = 4
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bytesPerInt64 = 8
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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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var result uint16
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for offset := uint64(0); offset < bytesPerInt16; offset++ {
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shift := uint8(bitsPerByte * offset)
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result += uint16(v.data[v.position+offset]) << shift
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}
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v.position += bytesPerInt16
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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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for offset := uint64(0); offset < bytesPerInt16; offset++ {
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shift := uint8(bitsPerByte * offset)
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result += int16(v.data[v.position+offset]) << shift
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}
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v.position += bytesPerInt16
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return result
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}
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// SetPosition sets the stream position with the given position
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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 dword from the stream
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func (v *StreamReader) GetUInt32() uint32 {
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var result uint32
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for offset := uint64(0); offset < bytesPerInt32; offset++ {
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shift := uint8(bitsPerByte * offset)
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result += uint32(v.data[v.position+offset]) << shift
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}
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v.position += bytesPerInt32
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return result
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}
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// GetInt32 returns an int32 dword from the stream
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func (v *StreamReader) GetInt32() int32 {
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var result int32
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for offset := uint64(0); offset < bytesPerInt32; offset++ {
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shift := uint8(bitsPerByte * offset)
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result += int32(v.data[v.position+offset]) << shift
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}
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v.position += bytesPerInt32
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return result
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}
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// GetUint64 returns a uint64 qword from the stream
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func (v *StreamReader) GetUint64() uint64 {
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var result uint64
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for offset := uint64(0); offset < bytesPerInt64; offset++ {
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shift := uint8(bitsPerByte * offset)
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result += uint64(v.data[v.position+offset]) << shift
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}
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v.position += bytesPerInt64
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return result
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}
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// GetInt64 returns a uint64 qword from the stream
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func (v *StreamReader) GetInt64() int64 {
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return int64(v.GetUint64())
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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 {
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result := v.data[v.position : v.position+uint64(count)]
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v.position += uint64(count)
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return result
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}
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// SkipBytes moves the stream position forward by the given amount
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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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// EOF returns if the stream position is reached to the end of the data, or not
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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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