From a37a13074c443c7104016187daad1e8171f0adc8 Mon Sep 17 00:00:00 2001
From: aiju <devnull@localhost>
Date: Tue, 20 Dec 2016 18:33:58 +0100
Subject: mpxor: sign should be 1/-1, not 0/-1

---
 sys/src/libmp/port/mplogic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sys/src/libmp/port/mplogic.c b/sys/src/libmp/port/mplogic.c
index a3258e45b..378bfc7ee 100644
--- a/sys/src/libmp/port/mplogic.c
+++ b/sys/src/libmp/port/mplogic.c
@@ -104,7 +104,7 @@ mpxor(mpint *b1, mpint *b2, mpint *sum)
 		b2 = t;
 	}
 	fl = (b1->sign & 10) ^ (b2->sign & 12);
-	sum->sign = (int)(fl << 28) >> 31;
+	sum->sign = (int)(fl << 28) >> 31 | 1;
 	mpbits(sum, b1->top*Dbits);
 	dp1 = b1->p;
 	dp2 = b2->p;
-- 
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