ml
60 lines
1.4 KiB
Go
60 lines
1.4 KiB
Go
package compression
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// MaskstreamWriter writes mask integers to a byte array.
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type MaskstreamWriter struct {
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Buffer []byte
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}
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// Write adds the given amount of bytes from the mask to the buffer.
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func (w *MaskstreamWriter) Write(byteCount uint, mask uint64) error {
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if byteCount > 8 {
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return errInvalidByteCount
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}
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if w.Buffer == nil {
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w.Buffer = make([]byte, 0, 1024*32)
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}
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for b := uint(0); b < byteCount; b++ {
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w.Buffer = append(w.Buffer, byte(mask>>(b*8)))
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}
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return nil
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}
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// MaskstreamReader reads mask integers from a byte array.
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type MaskstreamReader struct {
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source []byte
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curPos int
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}
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// NewMaskstreamReader returns a new reader instance for given source.
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func NewMaskstreamReader(source []byte) *MaskstreamReader {
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return &MaskstreamReader{source: source}
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}
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// Read returns a mask integer of given byte length from the current position.
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// If the current position is at or beyond the available size, 0x00 is assumed for the missing bytes.
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//
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// Reading more than 8, or less than 0, bytes panics.
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func (reader *MaskstreamReader) Read(bytes int) (value uint64) {
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if bytes > 8 {
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panic("Limit of byte count: 8")
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}
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if bytes < 0 {
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panic("Minimum byte count: 0")
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}
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for i := 0; i < bytes; i++ {
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value |= reader.nextByte() << uint64(8*i)
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}
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return
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}
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func (reader *MaskstreamReader) nextByte() (value uint64) {
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if reader.curPos < len(reader.source) {
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value = uint64(reader.source[reader.curPos])
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reader.curPos++
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}
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return
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}
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