bug corrections

*correct a bug which was causing brutal gpu usage loss after finding a
share on stratum
* add a uint32 method xandor in cuda_helper to be used in sha256 (faster
than the uint64 original designed for sha512)

ccminer.cpp

@@ -1283,7 +1283,7 @@ static void *miner_thread(void *userdata)
 
 		if (have_stratum) {
 			uint32_t sleeptime = 0;
-			while (!work_done && time(NULL) >= (g_work_time + opt_scantime)) {
+			while (!work_done && time(NULL) >= (g_work_time + 60)) {
 				usleep(100*1000);
 				if (sleeptime > 4) {
 					extrajob = true;

cuda_helper.h

@@ -249,6 +249,21 @@ uint64_t xandx(uint64_t a, uint64_t b, uint64_t c)
 	return result;
 }
 
+__device__ __forceinline__
+uint32_t xandx(uint32_t a, uint32_t b, uint32_t c)
+{
+	uint32_t result;
+	asm("{\n\t"
+		".reg .u32 n;\n\t"
+		"xor.b32 %0, %2, %3;\n\t"
+		"and.b32 n, %0, %1;\n\t"
+		"xor.b32 %0, n, %3;"
+		"}\n"
+		: "=r"(result) : "r"(a), "r"(b), "r"(c));
+	return result;
+}
+
+
 // device asm for x17
 __device__ __forceinline__
 uint64_t sph_t64(uint64_t x)