1 files changed, 63 insertions, 0 deletions
diff --git a/object/id/algorithm_tables.go b/object/id/algorithm_tables.go
new file mode 100644
index 00000000..86e1341e
--- /dev/null
+++ b/object/id/algorithm_tables.go
@@ -0,0 +1,63 @@
+package objectid
+
+import (
+	"crypto/sha1"
+	"crypto/sha256"
+)
+
+//nolint:gochecknoglobals
+var algorithmTable = [...]algorithmDetails{
+	AlgorithmUnknown: {},
+	AlgorithmSHA1: {
+		name:       "sha1",
+		size:       sha1.Size,
+		packHashID: 1,
+		sum: func(data []byte) ObjectID {
+			sum := sha1.Sum(data) //#nosec G401
+
+			var id ObjectID
+			copy(id.data[:], sum[:])
+			id.algo = AlgorithmSHA1
+
+			return id
+		},
+		new: sha1.New,
+	},
+	AlgorithmSHA256: {
+		name:       "sha256",
+		size:       sha256.Size,
+		packHashID: 2,
+		sum: func(data []byte) ObjectID {
+			sum := sha256.Sum256(data)
+
+			var id ObjectID
+			copy(id.data[:], sum[:])
+			id.algo = AlgorithmSHA256
+
+			return id
+		},
+		new: sha256.New,
+	},
+}
+
+var (
+	//nolint:gochecknoglobals
+	algorithmByName = map[string]Algorithm{}
+	//nolint:gochecknoglobals
+	supportedAlgorithms []Algorithm
+)
+
+func init() { //nolint:gochecknoinits
+	emptyTreeInput := []byte("tree 0\x00")
+
+	for algo := Algorithm(0); int(algo) < len(algorithmTable); algo++ {
+		info := &algorithmTable[algo]
+		if info.name == "" {
+			continue
+		}
+
+		info.emptyTree = info.sum(emptyTreeInput)
+		algorithmByName[info.name] = algo
+		supportedAlgorithms = append(supportedAlgorithms, algo)
+	}
+}