Fixed #6. Disable multi-thread swap when incx==0 or incy==0.

interface/swap.c

@@ -78,7 +78,12 @@ void CNAME(blasint n, FLOAT *x, blasint incx, FLOAT *y, blasint incy){
 
 #ifdef SMP
   nthreads = num_cpu_avail(1);
-
+  
+  //disable multi-thread when incx==0 or incy==0
+  //In that case, the threads would be dependent.
+  if (incx == 0 || incy == 0)
+	  nthreads = 1;
+  
   if (nthreads == 1) {
 #endif
 

interface/zswap.c

@@ -80,6 +80,11 @@ void CNAME(blasint n, FLOAT *x, blasint incx, FLOAT *y, blasint incy){
 #ifdef SMP
   nthreads = num_cpu_avail(1);
 
+  //disable multi-thread when incx==0 or incy==0
+  //In that case, the threads would be dependent.
+  if (incx == 0 || incy == 0)
+	  nthreads = 1;
+
   if (nthreads == 1) {
 #endif