ml
47 lines
1.1 KiB
Go
47 lines
1.1 KiB
Go
package compression
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import (
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"bytes"
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"encoding/binary"
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)
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// UnpackControlWords reads from an encoded string of bytes a series of packed control words.
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// If all is OK, the control words are returned. If the function returns an error, something
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// could not be read/decoded properly.
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func UnpackControlWords(data []byte) (words []ControlWord, err error) {
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if len(data) < 4 {
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return nil, ErrFormat
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}
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var controlBytes uint32
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reader := bytes.NewReader(data)
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err = binary.Read(reader, binary.LittleEndian, &controlBytes)
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if err != nil {
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return
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}
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if controlBytes%bytesPerControlWord != 0 {
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return nil, ErrFormat
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}
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wordCount := int(controlBytes / bytesPerControlWord)
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unpacked := 0
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words = make([]ControlWord, wordCount)
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for unpacked < wordCount {
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var packed PackedControlWord
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err = binary.Read(reader, binary.LittleEndian, &packed)
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if err != nil {
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return
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}
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times := packed.Times()
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if times > len(words)-unpacked {
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return nil, ErrFormat
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}
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for i := 0; i < times; i++ {
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words[unpacked+i] = packed.Value()
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}
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unpacked += times
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}
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return
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}
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