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package idxfile
import "gopkg.in/src-d/go-git.v4/core"
const (
// VersionSupported is the only idx version supported.
VersionSupported = 2
)
var (
idxHeader = []byte{255, 't', 'O', 'c'}
)
// An Idxfile represents an idx file in memory.
type Idxfile struct {
Version uint32
Fanout [255]uint32
ObjectCount uint32
Entries []Entry
PackfileChecksum [20]byte
IdxChecksum [20]byte
}
// An Entry represents data about an object in the packfile: its hash,
// offset and CRC32 checksum.
type Entry struct {
Hash core.Hash
CRC32 uint32
Offset uint64
}
func (idx *Idxfile) Add(h core.Hash, offset uint64, crc32 uint32) {
idx.Entries = append(idx.Entries, Entry{
Hash: h,
Offset: offset,
CRC32: crc32,
})
}
func (idx *Idxfile) isValid() bool {
fanout := idx.calculateFanout()
for k, c := range idx.Fanout {
if fanout[k] != c {
return false
}
}
return true
}
func (idx *Idxfile) calculateFanout() [256]uint32 {
fanout := [256]uint32{}
for _, e := range idx.Entries {
fanout[e.Hash[0]]++
}
for i := 1; i < 256; i++ {
fanout[i] += fanout[i-1]
}
return fanout
}
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