format: Move commitgraph and packfile here

1 files changed, 117 insertions, 0 deletions

diff --git a/format/commitgraph/bloom/key.go b/format/commitgraph/bloom/key.go
new file mode 100644
index 00000000..a15df904
--- /dev/null
+++ b/format/commitgraph/bloom/key.go
@@ -0,0 +1,117 @@
+package bloom
+
+import "codeberg.org/lindenii/furgit/internal/intconv"
+
+type key struct {
+	hashes []uint32
+}
+
+func keyvec(path []byte, filter *Filter) ([]key, error) {
+	if len(path) == 0 {
+		return nil, nil
+	}
+
+	count := 1
+
+	for _, b := range path {
+		if b == '/' {
+			count++
+		}
+	}
+
+	keys := make([]key, 0, count)
+
+	full, err := keyFill(path, filter)
+	if err != nil {
+		return nil, err
+	}
+
+	keys = append(keys, full)
+
+	for i := len(path) - 1; i >= 0; i-- {
+		if path[i] == '/' {
+			k, err := keyFill(path[:i], filter)
+			if err != nil {
+				return nil, err
+			}
+
+			keys = append(keys, k)
+		}
+	}
+
+	return keys, nil
+}
+
+func keyFill(path []byte, filter *Filter) (key, error) {
+	const (
+		seed0 = 0x293ae76f
+		seed1 = 0x7e646e2c
+	)
+
+	var (
+		h0  uint32
+		h1  uint32
+		err error
+	)
+
+	switch filter.HashVersion {
+	case 2:
+		h0, err = murmur3SeededV2(seed0, path)
+		if err != nil {
+			return key{}, err
+		}
+
+		h1, err = murmur3SeededV2(seed1, path)
+		if err != nil {
+			return key{}, err
+		}
+	case 1:
+		h0, err = murmur3SeededV1(seed0, path)
+		if err != nil {
+			return key{}, err
+		}
+
+		h1, err = murmur3SeededV1(seed1, path)
+		if err != nil {
+			return key{}, err
+		}
+	default:
+		return key{}, ErrInvalid
+	}
+
+	hashCount, err := intconv.Uint32ToInt(filter.NumHashes)
+	if err != nil {
+		return key{}, ErrInvalid
+	}
+
+	hashes := make([]uint32, hashCount)
+	for i := range hashCount {
+		iU32, err := intconv.IntToUint32(i)
+		if err != nil {
+			return key{}, ErrInvalid
+		}
+
+		hashes[i] = h0 + iU32*h1
+	}
+
+	return key{hashes: hashes}, nil
+}
+
+func filterContainsKey(filter *Filter, key key) bool {
+	if len(filter.Data) == 0 {
+		return false
+	}
+
+	mod := uint64(len(filter.Data)) * 8
+	for _, h := range key.hashes {
+		idx := uint64(h) % mod
+		bytePos := idx / 8
+
+		bit := byte(1 << (idx & 7))
+		if filter.Data[bytePos]&bit == 0 {
+			return false
+		}
+	}
+
+	return true
+}