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authorDaniel Vetter <daniel.vetter@ffwll.ch>2016-02-12 14:24:37 +0100
committerDaniel Vetter <daniel.vetter@ffwll.ch>2016-02-12 14:24:37 +0100
commit05fd934ba585ea8c9f129f15f11327adb1f96fe3 (patch)
tree7b678c512c43419ccf484e71c84d69caee84a6da /tools/lib/find_bit.c
parentebb7c78d358b2ea45c7d997423e6feb42e5ce4ef (diff)
parent382ab95d1af85381d8a5dff09b16a80c7e492534 (diff)
Merge tag 'topic/drm-misc-2016-02-12' into drm-intel-next-queued
Backmerge to get at the new encoder_mask support in atomic helpers. Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Diffstat (limited to 'tools/lib/find_bit.c')
-rw-r--r--tools/lib/find_bit.c84
1 files changed, 84 insertions, 0 deletions
diff --git a/tools/lib/find_bit.c b/tools/lib/find_bit.c
new file mode 100644
index 000000000000..9122a9e80046
--- /dev/null
+++ b/tools/lib/find_bit.c
@@ -0,0 +1,84 @@
+/* bit search implementation
+ *
+ * Copied from lib/find_bit.c to tools/lib/find_bit.c
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * Copyright (C) 2008 IBM Corporation
+ * 'find_last_bit' is written by Rusty Russell <rusty@rustcorp.com.au>
+ * (Inspired by David Howell's find_next_bit implementation)
+ *
+ * Rewritten by Yury Norov <yury.norov@gmail.com> to decrease
+ * size and improve performance, 2015.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/bitops.h>
+#include <linux/bitmap.h>
+#include <linux/kernel.h>
+
+#if !defined(find_next_bit)
+
+/*
+ * This is a common helper function for find_next_bit and
+ * find_next_zero_bit. The difference is the "invert" argument, which
+ * is XORed with each fetched word before searching it for one bits.
+ */
+static unsigned long _find_next_bit(const unsigned long *addr,
+ unsigned long nbits, unsigned long start, unsigned long invert)
+{
+ unsigned long tmp;
+
+ if (!nbits || start >= nbits)
+ return nbits;
+
+ tmp = addr[start / BITS_PER_LONG] ^ invert;
+
+ /* Handle 1st word. */
+ tmp &= BITMAP_FIRST_WORD_MASK(start);
+ start = round_down(start, BITS_PER_LONG);
+
+ while (!tmp) {
+ start += BITS_PER_LONG;
+ if (start >= nbits)
+ return nbits;
+
+ tmp = addr[start / BITS_PER_LONG] ^ invert;
+ }
+
+ return min(start + __ffs(tmp), nbits);
+}
+#endif
+
+#ifndef find_next_bit
+/*
+ * Find the next set bit in a memory region.
+ */
+unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
+ unsigned long offset)
+{
+ return _find_next_bit(addr, size, offset, 0UL);
+}
+#endif
+
+#ifndef find_first_bit
+/*
+ * Find the first set bit in a memory region.
+ */
+unsigned long find_first_bit(const unsigned long *addr, unsigned long size)
+{
+ unsigned long idx;
+
+ for (idx = 0; idx * BITS_PER_LONG < size; idx++) {
+ if (addr[idx])
+ return min(idx * BITS_PER_LONG + __ffs(addr[idx]), size);
+ }
+
+ return size;
+}
+#endif