Introduced macro _CS__ for calculated chapter/section/sub... level headings.

diff --git a/gas/doc/pretex.m4 b/gas/doc/pretex.m4
index 826c1282bcdc97289229c1de2362e2ec9a4e6d0c..da62d49555350627ac626f3da81b49de6ad9e595 100644 (file)
--- a/gas/doc/pretex.m4
+++ b/gas/doc/pretex.m4
@@ -219,4 +219,34 @@ _define__(
                <<>_dnl__<>>,
                <_popf__<>_ifelse__(0,_IF_FS__,
                        <_divert__<>_dnl__<>>,<>)>)>)
+
+D. CHAPTER/SECTION MACRO
+In a parametrized manual, the heading level may need to be calculated;
+for example, a manual that has a chapter on machine dependencies
+should be conditionally structured as follows:
+       - IF the manual is configured for a SINGLE machine type,  use
+the chapter heading for that machine type, and run headings down
+from there (top level for a particular machine is chapter, then within
+that we have section, subsection etc);
+       - ELSE, if MANY machine types are described in the chapter,
+use a generic chapter heading such as "@chapter Machine Dependencies",
+use "section" for the top level description of EACH machine, and run
+headings down from there (top level for a particular machine is
+section, then within that we have subsection, subsubsection etc).
+
+The macro <_CS__> is for this purpose: its argument is evaluated (so
+you can construct expressions to express choices such as above), then
+expands as follows:
+   0: @chapter
+   1: @section
+   2: @subsection
+   3: @subsubsection
+ ...and so on.
+
+_define__(<_CS__>,<@_cs__(_eval__($1))>)
+_define__(<_cs__>,<_ifelse__(
+                       0, $1, <chapter>,
+                       1, $1, <section>,
+                               <sub<>_cs__(_eval__($1 - 1))>)>)
+
 _divert__<>_dnl__<>