cutils: Add test for buffer_is_zero

Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-Id: <1472496380-19706-6-git-send-email-rth@twiddle.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/util/bufferiszero.c b/util/bufferiszero.c
index a3a842f9fd..4af3caa1b6 100644
--- a/util/bufferiszero.c
+++ b/util/bufferiszero.c
@@ -162,6 +162,19 @@ static void __attribute__((constructor)) init_cpuid_cache(void)
     cpuid_cache = cache;
 }
 
+#define HAVE_NEXT_ACCEL
+bool test_buffer_is_zero_next_accel(void)
+{
+    /* If no bits set, we just tested buffer_zero_int, and there
+       are no more acceleration options to test.  */
+    if (cpuid_cache == 0) {
+        return false;
+    }
+    /* Disable the accelerator we used before and select a new one.  */
+    cpuid_cache &= cpuid_cache - 1;
+    return true;
+}
+
 static bool select_accel_fn(const void *buf, size_t len)
 {
     uintptr_t ibuf = (uintptr_t)buf;
@@ -180,6 +193,13 @@ static bool select_accel_fn(const void *buf, size_t len)
 #define select_accel_fn  buffer_zero_int
 #endif
 
+#ifndef HAVE_NEXT_ACCEL
+bool test_buffer_is_zero_next_accel(void)
+{
+    return false;
+}
+#endif
+
 /*
  * Checks if a buffer is all zeroes
  */