+typedef struct {
+ u32b dw[2];
+} u64b;
+
+static u64b u64b_xor(u64b a, u64b b)
+{
+ u64b result;
+
+ result.dw[0] = a.dw[0] ^ b.dw[0];
+ result.dw[1] = a.dw[1] ^ b.dw[1];
+
+ return result;
+}
+
+static u64b u64b_shiftl(u64b x, int k)
+{
+ u64b result;
+
+ if (k < 32) {
+ result.dw[1] = (x.dw[1] << k) | (x.dw[0] >> (32 - k));
+ result.dw[0] = (x.dw[0] << k);
+ }
+ else {
+ result.dw[1] = (x.dw[0] << (k - 32));
+ result.dw[0] = 0;
+ }
+
+ return result;
+}
+
+static u64b u64b_rotl(u64b x, int k)
+{
+ u64b result;
+
+ if (k < 32) {
+ result.dw[0] = (x.dw[0] << k) | (x.dw[1] >> (32 - k));
+ result.dw[1] = (x.dw[1] << k) | (x.dw[0] >> (32 - k));
+ }
+ else {
+ result.dw[0] = (x.dw[0] >> (64 - k)) | (x.dw[1] << (k - 32));
+ result.dw[1] = (x.dw[1] >> (64 - k)) | (x.dw[0] << (k - 32));
+ }
+
+ return result;
+}
+
+static u64b u64b_add(u64b a, u64b b)
+{
+ u64b result;
+
+ result.dw[0] = a.dw[0] + b.dw[0];
+ result.dw[1] = a.dw[1] + b.dw[1];
+
+ if (result.dw[0] < a.dw[0])
+ result.dw[1] ++;
+
+ return result;
+}
+