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-rw-r--r--fs/xfs/xfs_bit.c103
1 files changed, 103 insertions, 0 deletions
diff --git a/fs/xfs/xfs_bit.c b/fs/xfs/xfs_bit.c
index 48228848f5ae..fab0b6d5a41b 100644
--- a/fs/xfs/xfs_bit.c
+++ b/fs/xfs/xfs_bit.c
@@ -25,6 +25,109 @@
* XFS bit manipulation routines, used in non-realtime code.
*/
+#ifndef HAVE_ARCH_HIGHBIT
+/*
+ * Index of high bit number in byte, -1 for none set, 0..7 otherwise.
+ */
+static const char xfs_highbit[256] = {
+ -1, 0, 1, 1, 2, 2, 2, 2, /* 00 .. 07 */
+ 3, 3, 3, 3, 3, 3, 3, 3, /* 08 .. 0f */
+ 4, 4, 4, 4, 4, 4, 4, 4, /* 10 .. 17 */
+ 4, 4, 4, 4, 4, 4, 4, 4, /* 18 .. 1f */
+ 5, 5, 5, 5, 5, 5, 5, 5, /* 20 .. 27 */
+ 5, 5, 5, 5, 5, 5, 5, 5, /* 28 .. 2f */
+ 5, 5, 5, 5, 5, 5, 5, 5, /* 30 .. 37 */
+ 5, 5, 5, 5, 5, 5, 5, 5, /* 38 .. 3f */
+ 6, 6, 6, 6, 6, 6, 6, 6, /* 40 .. 47 */
+ 6, 6, 6, 6, 6, 6, 6, 6, /* 48 .. 4f */
+ 6, 6, 6, 6, 6, 6, 6, 6, /* 50 .. 57 */
+ 6, 6, 6, 6, 6, 6, 6, 6, /* 58 .. 5f */
+ 6, 6, 6, 6, 6, 6, 6, 6, /* 60 .. 67 */
+ 6, 6, 6, 6, 6, 6, 6, 6, /* 68 .. 6f */
+ 6, 6, 6, 6, 6, 6, 6, 6, /* 70 .. 77 */
+ 6, 6, 6, 6, 6, 6, 6, 6, /* 78 .. 7f */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* 80 .. 87 */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* 88 .. 8f */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* 90 .. 97 */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* 98 .. 9f */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* a0 .. a7 */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* a8 .. af */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* b0 .. b7 */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* b8 .. bf */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* c0 .. c7 */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* c8 .. cf */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* d0 .. d7 */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* d8 .. df */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* e0 .. e7 */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* e8 .. ef */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* f0 .. f7 */
+ 7, 7, 7, 7, 7, 7, 7, 7, /* f8 .. ff */
+};
+#endif
+
+/*
+ * xfs_highbit32: get high bit set out of 32-bit argument, -1 if none set.
+ */
+inline int
+xfs_highbit32(
+ __uint32_t v)
+{
+#ifdef HAVE_ARCH_HIGHBIT
+ return highbit32(v);
+#else
+ int i;
+
+ if (v & 0xffff0000)
+ if (v & 0xff000000)
+ i = 24;
+ else
+ i = 16;
+ else if (v & 0x0000ffff)
+ if (v & 0x0000ff00)
+ i = 8;
+ else
+ i = 0;
+ else
+ return -1;
+ return i + xfs_highbit[(v >> i) & 0xff];
+#endif
+}
+
+/*
+ * xfs_lowbit64: get low bit set out of 64-bit argument, -1 if none set.
+ */
+int
+xfs_lowbit64(
+ __uint64_t v)
+{
+ __uint32_t w = (__uint32_t)v;
+ int n = 0;
+
+ if (w) { /* lower bits */
+ n = ffs(w);
+ } else { /* upper bits */
+ w = (__uint32_t)(v >> 32);
+ if (w && (n = ffs(w)))
+ n += 32;
+ }
+ return n - 1;
+}
+
+/*
+ * xfs_highbit64: get high bit set out of 64-bit argument, -1 if none set.
+ */
+int
+xfs_highbit64(
+ __uint64_t v)
+{
+ __uint32_t h = (__uint32_t)(v >> 32);
+
+ if (h)
+ return xfs_highbit32(h) + 32;
+ return xfs_highbit32((__uint32_t)v);
+}
+
+
/*
* Return whether bitmap is empty.
* Size is number of words in the bitmap, which is padded to word boundary