From: Tomas Hruby <tom@minix3.org>
Date: Thu, 23 Sep 2010 14:42:26 +0000 (+0000)
Subject: neg64() makes a 64bit integer negative
X-Git-Tag: v3.2.0~804
X-Git-Url: http://zhaoyanbai.com/repos/%22http:/www.isc.org/icons/Bv9ARM.html?a=commitdiff_plain;h=274fcf8d1f9b0b7115bf3a7c02c9081581fa18a7;p=minix.git

neg64() makes a 64bit integer negative

- neg64(a) == -a

- although we only support 64 bit unsigned arithmetics sometimes it's good to
  have a 2-complement negative number
---

diff --git a/include/minix/u64.h b/include/minix/u64.h
index 910d77c28..4eef3fec2 100644
--- a/include/minix/u64.h
+++ b/include/minix/u64.h
@@ -43,4 +43,10 @@ u64_t not64(u64_t a);
 #define is_zero64(i)	((i).lo == 0 && (i).hi == 0)
 #define make_zero64(i)	do { (i).lo = (i).hi = 0; } while(0)
 
+#define neg64(i)	do {				\
+				(i).lo = ~(i).lo;	\
+				(i).hi = ~(i).hi;	\
+				(i) = add64u((i), 1);	\
+			} while(0)
+
 #endif /* _MINIX__U64_H */