From e15054a4f93fc54806e84aa7036e60168e78e823 Mon Sep 17 00:00:00 2001
From: Runxi Yu
Date: Fri, 6 Mar 2026 08:05:51 +0800
Subject: format/commitgraph: Add initial commit-graph support

---
 format/commitgraph/constants.go | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 format/commitgraph/constants.go

(limited to 'format/commitgraph/constants.go')

diff --git a/format/commitgraph/constants.go b/format/commitgraph/constants.go
new file mode 100644
index 00000000..96648fae
--- /dev/null
+++ b/format/commitgraph/constants.go
@@ -0,0 +1,32 @@
+package commitgraph
+
+const (
+	fileSignature = 0x43475048 // "CGPH"
+	fileVersion   = 1
+)
+
+const (
+	chunkOIDF = 0x4f494446 // "OIDF"
+	chunkOIDL = 0x4f49444c // "OIDL"
+	chunkCDAT = 0x43444154 // "CDAT"
+	chunkGDA2 = 0x47444132 // "GDA2"
+	chunkGDO2 = 0x47444f32 // "GDO2"
+	chunkEDGE = 0x45444745 // "EDGE"
+	chunkBIDX = 0x42494458 // "BIDX"
+	chunkBDAT = 0x42444154 // "BDAT"
+	chunkBASE = 0x42415345 // "BASE"
+)
+
+const (
+	headerSize     = 8
+	chunkEntrySize = 12
+	fanoutSize     = 256 * 4
+)
+
+const (
+	parentNone      = 0x70000000
+	parentExtraMask = 0x80000000
+	parentLastMask  = 0x7fffffff
+
+	generationOverflow = 0x80000000
+)
-- 
cgit v1.3.1-10-gc9f91