[PATCH v4 01/19] hash.h: provide constants for the hash IDs

["Han-Wen Nienhuys via GitGitGadget" <gitgitgadget@gmail.com>]

From: Han-Wen Nienhuys <hanwen@google.com>

This will simplify referencing them from code that is not deeply integrated with
Git, in particular, the reftable library.

Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
---
 hash.h        | 6 ++++++
 object-file.c | 7 ++-----
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/hash.h b/hash.h
index 9e25c40e9ac..5d40368f18a 100644
--- a/hash.h
+++ b/hash.h
@@ -95,12 +95,18 @@ static inline void git_SHA256_Clone(git_SHA256_CTX *dst, const git_SHA256_CTX *s
 /* Number of algorithms supported (including unknown). */
 #define GIT_HASH_NALGOS (GIT_HASH_SHA256 + 1)
 
+/* "sha1", big-endian */
+#define GIT_SHA1_FORMAT_ID 0x73686131
+
 /* The length in bytes and in hex digits of an object name (SHA-1 value). */
 #define GIT_SHA1_RAWSZ 20
 #define GIT_SHA1_HEXSZ (2 * GIT_SHA1_RAWSZ)
 /* The block size of SHA-1. */
 #define GIT_SHA1_BLKSZ 64
 
+/* "s256", big-endian */
+#define GIT_SHA256_FORMAT_ID 0x73323536
+
 /* The length in bytes and in hex digits of an object name (SHA-256 value). */
 #define GIT_SHA256_RAWSZ 32
 #define GIT_SHA256_HEXSZ (2 * GIT_SHA256_RAWSZ)
diff --git a/object-file.c b/object-file.c
index 112d9b4badc..b79ab75979f 100644
--- a/object-file.c
+++ b/object-file.c
@@ -165,7 +165,6 @@ static void git_hash_unknown_final_oid(struct object_id *oid, git_hash_ctx *ctx)
 	BUG("trying to finalize unknown hash");
 }
 
-
 const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
 	{
 		NULL,
@@ -184,8 +183,7 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
 	},
 	{
 		"sha1",
-		/* "sha1", big-endian */
-		0x73686131,
+		GIT_SHA1_FORMAT_ID,
 		GIT_SHA1_RAWSZ,
 		GIT_SHA1_HEXSZ,
 		GIT_SHA1_BLKSZ,
@@ -200,8 +198,7 @@ const struct git_hash_algo hash_algos[GIT_HASH_NALGOS] = {
 	},
 	{
 		"sha256",
-		/* "s256", big-endian */
-		0x73323536,
+		GIT_SHA256_FORMAT_ID,
 		GIT_SHA256_RAWSZ,
 		GIT_SHA256_HEXSZ,
 		GIT_SHA256_BLKSZ,
-- 
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