From b255b14872dfaa274ff52950c7bb264d197b0cc5 Mon Sep 17 00:00:00 2001
From: Jan Sucan <jan@jansucan.com>
Date: Sat, 9 Nov 2024 13:40:27 +0100
Subject: Add man page for the diff image format

---
 Makefile      |  6 ++++-
 config.mk     |  1 +
 man/diff-dd.5 | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 84 insertions(+), 1 deletion(-)
 create mode 100644 man/diff-dd.5

diff --git a/Makefile b/Makefile
index f799ed7..8014b02 100644
--- a/Makefile
+++ b/Makefile
@@ -15,6 +15,10 @@ install: all
 	mkdir -p ${DESTDIR}${PREFIX}/bin
 	cp -f src/diff-dd ${DESTDIR}${PREFIX}/bin
 	chmod 755 ${DESTDIR}${PREFIX}/bin/diff-dd
+	mkdir -p ${DESTDIR}${MANPREFIX}/man5
+	cp -f man/diff-dd.5 ${DESTDIR}${MANPREFIX}/man5/diff-dd.5
+	chmod 644 ${DESTDIR}${MANPREFIX}/man5/diff-dd.5
 
 uninstall:
-	rm -f ${DESTDIR}${PREFIX}/bin/diff-dd
+	rm -f ${DESTDIR}${PREFIX}/bin/diff-dd \
+		${DESTDIR}${MANPREFIX}/man5/diff-dd.5
diff --git a/config.mk b/config.mk
index 95099be..1f5dd33 100644
--- a/config.mk
+++ b/config.mk
@@ -2,6 +2,7 @@ PROGRAM_NAME = diff-dd
 PROGRAM_VERSION = 3.0.0-prealpha
 
 PREFIX = /usr/local
+MANPREFIX = ${PREFIX}/share/man
 
 CC=g++
 CFLAGS=-Wall -Wextra -Werror -std=c++17
diff --git a/man/diff-dd.5 b/man/diff-dd.5
new file mode 100644
index 0000000..9909e8c
--- /dev/null
+++ b/man/diff-dd.5
@@ -0,0 +1,78 @@
+.TH DIFF-DD 5
+
+.SH NAME
+diff-dd \- the file formats
+
+.SH DESCRIPTION
+This manual page describes the current and the previous formats of \%diff-dd\:
+differential images.
+
+.SS Format v1
+.I s
+is a sector size in bytes specified by the user on the command line when the
+image was being created.
+.I s
+is greater or equal 1.
+
+.I i
+is an index of data in a differential image starting from 0.
+
+The offsets are 64-bit little-endian.
+
+.TS
+tab(;) allbox;
+l l l
+l l l
+l l l
+l l l
+l l l
+l s s
+l l l.
+T{
+.B Offset (bytes)
+T};T{
+.B Size (bytes)
+T};T{
+.B Description
+T}
+.\"
+0;8;Offset of data 0 in the output file
+8;T{
+.I s
+T};Data 0
+.\"
+T{
+8 +
+.I s
+T};8;Offset of data 1 in the output file
+T{
+16 +
+.I s
+T};T{
+.I s
+T};Data 1
+.\"
+\[char46]\[char46]\[char46]
+T{
+(8 +
+.I s
+) *
+.I i
+T};8;T{
+Offset of data
+.I i
+in the output file
+T}
+T{
+(8 +
+.I s
+) *
+.I i
++ 8
+T};T{
+.I s
+T};T{
+Data
+.I i
+T}
+.TE
-- 
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