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