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package ingest
import (
"fmt"
"io"
)
// readOfsDistanceFromStream reads one ofs-delta encoded distance.
func readOfsDistanceFromStream(reader io.ByteReader) (uint64, int, error) {
first, err := reader.ReadByte()
if err != nil {
return 0, 0, fmt.Errorf("read ofs distance first byte: %w", err)
}
dist := uint64(first & 0x7f)
consumed := 1
b := first
for b&0x80 != 0 {
b, err = reader.ReadByte()
if err != nil {
return 0, 0, fmt.Errorf("read ofs distance continuation: %w", err)
}
consumed++
dist = ((dist + 1) << 7) + uint64(b&0x7f)
}
return dist, consumed, nil
}
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