Implement cpu_get_real_ticks for Alpha.

Signed-off-by: NRichard Henderson <rth@twiddle.net>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

qemu-timer.h

@@ -209,6 +209,19 @@ static inline int64_t cpu_get_real_ticks(void)
     return (int64_t)(count * cyc_per_count);
 }
 
+#elif defined(__alpha__)
+
+static inline int64_t cpu_get_real_ticks(void)
+{
+    uint64_t cc;
+    uint32_t cur, ofs;
+
+    asm volatile("rpcc %0" : "=r"(cc));
+    cur = cc;
+    ofs = cc >> 32;
+    return cur - ofs;
+}
+
 #else
 /* The host CPU doesn't have an easily accessible cycle counter.
    Just return a monotonically increasing value.  This will be