xnu-4570.20.62.tar.gz

[apple/xnu.git] / osfmk / kern / bits.h

diff --git a/osfmk/kern/bits.h b/osfmk/kern/bits.h
index 0305208a8a92ec8aa723c35d0fea25d46e737a92..5c977497d662ddfbea1f9b7699b83b356fe5e41b 100644 (file)
--- a/osfmk/kern/bits.h
+++ b/osfmk/kern/bits.h
@@ -47,11 +47,35 @@ typedef unsigned int                        uint;
 #define bit_clear(x, b)                        ((x) &= ~BIT(b))
 #define bit_test(x, b)                 ((bool)((x) & BIT(b)))
 
+/* Non-atomically clear the bit and returns whether the bit value was changed */
+inline static bool
+bit_clear_if_set(uint64_t bitmap, int bit)
+{
+    bool bit_is_set = bit_test(bitmap, bit);
+    bit_clear(bitmap, bit);
+    return bit_is_set;
+}
+
+/* Non-atomically set the bit and returns whether the bit value was changed */
+inline static bool
+bit_set_if_clear(uint64_t bitmap, int bit)
+{
+    bool bit_is_set = bit_test(bitmap, bit);
+    bit_set(bitmap, bit);
+    return !bit_is_set;
+}
+
 /* Returns the most significant '1' bit, or -1 if all zeros */
 inline static int
 bit_first(uint64_t bitmap)
 {
+#if defined(__arm64__)
+       int64_t result;
+       asm volatile("clz %0, %1" : "=r" (result) : "r" (bitmap));
+       return 63 - (int)result;
+#else
        return (bitmap == 0) ? -1 : 63 - __builtin_clzll(bitmap);
+#endif
 }