comment a bit the code in acinclude.m4

There is still a lot of code to clean up there, but hopefully
this should clarify what goes on in there.


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@89448 65c4cc65-6c06-0410-ace0-fbb531ad65f3

acinclude.m4

+# Various support functions for configure.ac in asterisk
+#
+
+# Helper function to check for gcc attributes.
 # AST_GCC_ATTRIBUTE([attribute name])
 
 AC_DEFUN([AST_GCC_ATTRIBUTE],
@@ -11,35 +15,43 @@ AC_COMPILE_IFELSE(
 	AC_MSG_RESULT(no))
 ])
 
-# AST_EXT_LIB_SETUP([package symbol name], [package friendly name], [package option name], [additional help text])
+# Helper function to setup variables for a package.
+# $1 -> the package name. Used in configure.ac and also as a prefix
+#	for the variables ($1_DIR, $1_INCLUDE, $1_LIB) in makeopts
+# $3 ->	option name, used in --with-$3 or --without-$3 when calling configure.
+# $2 and $4 are just text describing the package (short and long form)
+
+# AST_EXT_LIB_SETUP([package], [short description], [configure option name], [long description])
 
 AC_DEFUN([AST_EXT_LIB_SETUP],
 [
-$1_DESCRIP="$2"
-$1_OPTION="$3"
-AC_ARG_WITH([$3], AC_HELP_STRING([--with-$3=PATH],[use $2 files in PATH $4]),[
-case ${withval} in
-     n|no)
-     USE_$1=no
-     ;;
-     y|ye|yes)
-     ac_mandatory_list="${ac_mandatory_list} $1"
-     ;;
-     *)
-     $1_DIR="${withval}"
-     ac_mandatory_list="${ac_mandatory_list} $1"
-     ;;
-esac
-])
-PBX_$1=0
-AC_SUBST([$1_LIB])
-AC_SUBST([$1_INCLUDE])
-AC_SUBST([$1_DIR])
-AC_SUBST([PBX_$1])
+    $1_DESCRIP="$2"
+    $1_OPTION="$3"
+    AC_ARG_WITH([$3], AC_HELP_STRING([--with-$3=PATH],[use $2 files in PATH $4]),
+    [
+	case ${withval} in
+	n|no)
+	USE_$1=no
+	;;
+	y|ye|yes)
+	ac_mandatory_list="${ac_mandatory_list} $1"
+	;;
+	*)
+	$1_DIR="${withval}"
+	ac_mandatory_list="${ac_mandatory_list} $1"
+	;;
+	esac
+    ])
+    PBX_$1=0
+    AC_SUBST([$1_LIB])
+    AC_SUBST([$1_INCLUDE])
+    AC_SUBST([$1_DIR])
+    AC_SUBST([PBX_$1])
 ])
 
 # Check whether any of the mandatory modules are not present, and
-# print error messages in case.
+# print error messages in case. The mandatory list is built using
+# --with-* arguments when invoking configure.
 
 AC_DEFUN([AST_CHECK_MANDATORY],
 [
@@ -61,16 +73,22 @@ AC_DEFUN([AST_CHECK_MANDATORY],
 	AC_MSG_RESULT(ok)
 ])
 
-#-- The following two tests are only performed if PBX_$1 != 1,
-#   so you can use multiple tests and stop at the first matching one.
-#   On success, set PBX_$1 = 1, and also #define HAVE_$1 1
-#   and #define HAVE_$1_VERSION ${last_argument} so you can tell which
-#   test succeeded.
-#   They should be called after AST_EXT_LIB_SETUP($1, ...)
+# The next three functions check for the availability of a given package.
+# AST_C_DEFINE_CHECK looks for the presence of a #define in a header file,
+# AST_EXT_LIB_CHECK looks for a symbol in a given library, or at least
+#	for the presence of a header file.
+# AST_EXT_TOOL_CHECK looks for a symbol in using $1-config to determine CFLAGS and LIBS
+#
+# They are only run if PBX_$1 != 1 (where $1 is the package),
+# so you can call them multiple times and stop at the first matching one.
+# On success, they both set PBX_$1 = 1, set $1_INCLUDE and $1_LIB as applicable,
+# and also #define HAVE_$1 1 and #define HAVE_$1_VERSION ${last_argument}
+# in autoconfig.h so you can tell which test succeeded.
+# They should be called after AST_EXT_LIB_SETUP($1, ...)
 
 # Check if a given macro is defined in a certain header.
 
-# AST_C_DEFINE_CHECK([package symbol name], [macro name], [header file], [version])
+# AST_C_DEFINE_CHECK([package], [macro name], [header file], [version])
 AC_DEFUN([AST_C_DEFINE_CHECK],
 [
     if test "x${PBX_$1}" != "x1" -a "${USE_$1}" != "no"; then
@@ -99,7 +117,7 @@ AC_DEFUN([AST_C_DEFINE_CHECK],
 # in a library, or, if no function is supplied, only check for the
 # existence of the header files.
 
-# AST_EXT_LIB_CHECK([package symbol name], [package library name], [function to check], [package header], [additional LIB data], [version])
+# AST_EXT_LIB_CHECK([package], [library], [function], [header], [additional LIB data], [version])
 AC_DEFUN([AST_EXT_LIB_CHECK],
 [
 if test "x${PBX_$1}" != "x1" -a "${USE_$1}" != "no"; then
@@ -152,21 +170,22 @@ fi
 ])
 
 
-# check for a tool using xxx-config
-# AST_EXT_TOOL_CHECK([package symbol name], [package library name], [symbol], [version])
+# Check for a package using $2-config. Similar to AST_EXT_LIB_CHECK,
+# but use $2-config to determine cflags and libraries to use.
+
+# AST_EXT_TOOL_CHECK([package], [tool name], [symbol], [version])
 AC_DEFUN([AST_EXT_TOOL_CHECK],
 [
-PBX_$1=0
-AC_CHECK_TOOL(CONFIG_$1, $2-config, No)
-if test ! "x${CONFIG_$1}" = xNo; then
-   $1_INCLUDE=$(${CONFIG_$1} --cflags $3)
-   $1_LIB=$(${CONFIG_$1} --libs $3)
-   PBX_$1=1
-   AC_DEFINE([HAVE_$1], 1, [Define if your system has the $1 libraries.])
-fi
-AC_SUBST(PBX_$1)
-AC_SUBST($1_INCLUDE)
-AC_SUBST($1_LIB)
+    if test "x${PBX_$1}" != "x1" -a "${USE_$1}" != "no"; then
+	PBX_$1=0
+	AC_CHECK_TOOL(CONFIG_$1, $2-config, No)
+	if test ! "x${CONFIG_$1}" = xNo; then
+	    $1_INCLUDE=$(${CONFIG_$1} --cflags $3)
+	    $1_LIB=$(${CONFIG_$1} --libs $3)
+	    PBX_$1=1
+	    AC_DEFINE([HAVE_$1], 1, [Define if your system has the $1 libraries.])
+	fi
+    fi
 ])
 
 AC_DEFUN(
@@ -830,7 +849,8 @@ dnl @author Steven G. Johnson <stevenj@alum.mit.edu>
 dnl @version 2006-05-29
 dnl @license GPLWithACException
 
-AC_DEFUN([ACX_PTHREAD], [
+AC_DEFUN([ACX_PTHREAD],
+[
 AC_REQUIRE([AC_CANONICAL_HOST])
 AC_LANG_SAVE
 AC_LANG_C