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package needle
import ( "fmt" "io"
"hash/crc32"
"github.com/seaweedfs/seaweedfs/weed/util" )
var table = crc32.MakeTable(crc32.Castagnoli)
type CRC uint32
func NewCRC(b []byte) CRC { return CRC(0).Update(b) }
func (c CRC) Update(b []byte) CRC { return CRC(crc32.Update(uint32(c), table, b)) }
// Value Deprecated. Just use the raw uint32 value to compare.
func (c CRC) Value() uint32 { return uint32(c>>15|c<<17) + 0xa282ead8 }
func (n *Needle) Etag() string { bits := make([]byte, 4) util.Uint32toBytes(bits, uint32(n.Checksum)) return fmt.Sprintf("%x", bits) }
func NewCRCwriter(w io.Writer) *CRCwriter {
return &CRCwriter{ crc: CRC(0), w: w, }
}
type CRCwriter struct { crc CRC w io.Writer }
func (c *CRCwriter) Write(p []byte) (n int, err error) { n, err = c.w.Write(p) // with each write ...
c.crc = c.crc.Update(p) return }
func (c *CRCwriter) Sum() uint32 { return uint32(c.crc) } // final hash
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