seaweedfs/weed/storage/needle/crc.go
2021-03-06 14:26:27 -08:00

55 lines
893 B
Go

package needle
import (
"fmt"
"io"
"github.com/klauspost/crc32"
"github.com/chrislusf/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))
}
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 c.crc.Value() } // final hash