mirror of
https://github.com/seaweedfs/seaweedfs.git
synced 2024-12-02 00:19:15 +08:00
55 lines
879 B
Go
55 lines
879 B
Go
package needle
|
|
|
|
import (
|
|
"fmt"
|
|
"io"
|
|
|
|
"hash/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
|