From 142429e5ae9ac82c3e37af759f12d058f8259e23 Mon Sep 17 00:00:00 2001
From: Aaron Carroll <aaronc@cse.unsw.edu.au>
Date: Thu, 14 Mar 2013 16:57:39 +1100
Subject: [PATCH] configure: compile-time word size detection

Signed-off-by: Aaron Carroll <aaronc@cse.unsw.edu.au>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 configure | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/configure b/configure
index 1fa9b635..84c6af28 100755
--- a/configure
+++ b/configure
@@ -348,16 +348,20 @@ echo
 # check for wordsize
 wordsize="0"
 cat > $TMPC <<EOF
-#include <stdio.h>
+#include <limits.h>
+#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
 int main(void)
 {
-  unsigned int wsize = sizeof(long) * 8;
-  printf("%d\n", wsize);
+  BUILD_BUG_ON(sizeof(long)*CHAR_BIT != WORDSIZE);
   return 0;
 }
 EOF
-if compile_prog "" "" "wordsize"; then
-  wordsize=`$TMPE`
+if compile_prog "-DWORDSIZE=32" "" "wordsize"; then
+  wordsize="32"
+elif compile_prog "-DWORDSIZE=64" "" "wordsize"; then
+  wordsize="64"
+else
+  fatal "Unknown wordsize"
 fi
 echo "Wordsize                      $wordsize"
 
-- 
2.25.1