From 51b21b169ac0336e69ee9f8f95f3ac18ef97a567 Mon Sep 17 00:00:00 2001
From: drh <drh@noemail.net>
Date: Tue, 25 May 2010 15:53:31 +0000
Subject: [PATCH] Updated header comments in wal.c.  No functional code
 changes.

FossilOrigin-Name: 687632a6b3a0aeb006c1eda5c27d5489f08c230e
---
 manifest      | 24 +++++++++++++++++-------
 manifest.uuid |  2 +-
 src/wal.c     |  9 +++++++++
 3 files changed, 27 insertions(+), 8 deletions(-)

diff --git a/manifest b/manifest
index 4d39854c5a..9f66cbf293 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,8 @@
-C Add\sa\sbusy-handler\sto\sa\stest\scase\sin\swalthread.test\sto\sprevent\serrors.
-D 2010-05-25T15:23:52
+-----BEGIN PGP SIGNED MESSAGE-----
+Hash: SHA1
+
+C Updated\sheader\scomments\sin\swal.c.\s\sNo\sfunctional\scode\schanges.
+D 2010-05-25T15:53:32
 F Makefile.arm-wince-mingw32ce-gcc fcd5e9cd67fe88836360bb4f9ef4cb7f8e2fb5a0
 F Makefile.in a5cad1f8f3e021356bfcc6c77dc16f6f1952bbc3
 F Makefile.linux-gcc d53183f4aa6a9192d249731c90dbdffbd2c68654
@@ -224,7 +227,7 @@ F src/vdbeblob.c 5327132a42a91e8b7acfb60b9d2c3b1c5c863e0e
 F src/vdbemem.c 2a82f455f6ca6f78b59fb312f96054c04ae0ead1
 F src/vdbetrace.c 864cef96919323482ebd9986f2132435115e9cc2
 F src/vtab.c a0f8a40274e4261696ef57aa806de2776ab72cda
-F src/wal.c 5088dfa9a5ea5f8aa327b358b80672396992d807
+F src/wal.c 910ec66f5ecaa5ddf11c2d621c41402c585844ad
 F src/wal.h 111c6f3efd83fe2fc707b29e26431e8eff4c6f28
 F src/walker.c 3112bb3afe1d85dc52317cb1d752055e9a781f8f
 F src/where.c 75fee9e255b62f773fcadd1d1f25b6f63ac7a356
@@ -815,7 +818,14 @@ F tool/speedtest2.tcl ee2149167303ba8e95af97873c575c3e0fab58ff
 F tool/speedtest8.c 2902c46588c40b55661e471d7a86e4dd71a18224
 F tool/speedtest8inst1.c 293327bc76823f473684d589a8160bde1f52c14e
 F tool/vdbe-compress.tcl d70ea6d8a19e3571d7ab8c9b75cba86d1173ff0f
-P 77438882dd53ac4d98b24e2846c87a2418b4e3d8
-R 23aa9622ccc545edb898221f105012e2
-U dan
-Z c7d8c33ddd8471f219d4b7cf868e8343
+P d3d348aa975c58c37088eb2830081880896b85e7
+R 0260887750a4ff2568ebba7befa4c293
+U drh
+Z b37d90009a6b0e9be74143cbddd6561b
+-----BEGIN PGP SIGNATURE-----
+Version: GnuPG v1.4.6 (GNU/Linux)
+
+iD8DBQFL+/J+oxKgR168RlERAs9wAJwJ+gskjCIcTQjaf9yUnO8hh8VQAACgjW95
+h2OPmMbpiQ7QHTW3OKLS5Hc=
+=mxeE
+-----END PGP SIGNATURE-----
diff --git a/manifest.uuid b/manifest.uuid
index aac31840c5..53450f9eb9 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-d3d348aa975c58c37088eb2830081880896b85e7
\ No newline at end of file
+687632a6b3a0aeb006c1eda5c27d5489f08c230e
\ No newline at end of file
diff --git a/src/wal.c b/src/wal.c
index 7c4543eb51..1f983edccf 100644
--- a/src/wal.c
+++ b/src/wal.c
@@ -68,6 +68,15 @@
 ** The checksum is computed using 32-bit big-endian integers if the
 ** magic number in the first 4 bytes of the WAL is 0x377f0683 and it
 ** is computed using little-endian if the magic number is 0x377f0682.
+** The checksum values are always stored in the frame header in a
+** big-endian format regardless of which byte order is used to compute
+** the checksum.  The checksum is computed by interpreting the input as
+** an even number of unsigned 32-bit integers: x[0] through x[N].  The
+** 
+**   for i from 0 to n-1 step 2:
+**     s0 += x[i] + s1;
+**     s1 += x[i+1] + s0;
+**   endfor
 **
 ** On a checkpoint, the WAL is first VFS.xSync-ed, then valid content of the
 ** WAL is transferred into the database, then the database is VFS.xSync-ed.
-- 
2.39.5