blob: 8409578866c112e3f245757764ab3ee1478db43b (
about) (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
package read
import (
"bytes"
"encoding/binary"
"codeberg.org/lindenii/furgit/internal/intconv"
objectid "codeberg.org/lindenii/furgit/object/id"
)
func layerLookup(layer *layer, oid objectid.ObjectID) (uint32, bool) {
hashSize := oid.Size()
first := int(oid.RawBytes()[0])
var lo uint32
if first > 0 {
lo = binary.BigEndian.Uint32(layer.chunkOIDFanout[(first-1)*4 : first*4])
}
hi := binary.BigEndian.Uint32(layer.chunkOIDFanout[first*4 : (first+1)*4])
if hi == 0 || lo >= hi {
return 0, false
}
target := oid.RawBytes()
left := int(lo)
right := int(hi) - 1
for left <= right {
mid := left + (right-left)/2
start := mid * hashSize
end := start + hashSize
current := layer.chunkOIDLookup[start:end]
cmp := bytes.Compare(current, target)
switch {
case cmp == 0:
pos, err := intconv.IntToUint32(mid)
if err != nil {
return 0, false
}
return pos, true
case cmp < 0:
left = mid + 1
default:
right = mid - 1
}
}
return 0, false
}
|
