bitmap: Add basic bitmap ops

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[stewart@linux.vnet.ibm.com: add (C) header]
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/core/bitmap.c b/core/bitmap.c
new file mode 100644
index 0000000..be0700f
--- /dev/null
+++ b/core/bitmap.c
@@ -0,0 +1,56 @@
+/* Copyright 2016 IBM Corp.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * 	http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+ * implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+#include "bitmap.h"
+
+static int __bitmap_find_bit(bitmap_t map, unsigned int start, unsigned int count,
+			     bool value)
+{
+	unsigned int el, first_bit;
+	unsigned int end = start + count;
+	bitmap_elem_t e, ev;
+	int b;
+
+	ev = value ? -1ul : 0;
+	el = BITMAP_ELEM(start);
+	first_bit = BITMAP_BIT(start);
+
+	while (start < end) {
+		e = map[el] ^ ev;
+		e |= ((1ul << first_bit) - 1);
+		if (~e)
+			break;
+		start = (start + BITMAP_ELSZ) & ~(BITMAP_ELSZ - 1);
+		first_bit = 0;
+		el++;
+	}
+	for (b = first_bit; b < BITMAP_ELSZ && start < end; b++,start++) {
+		if ((e & (1ull << b)) == 0)
+			return start;
+	}
+
+	return -1;
+}
+
+int bitmap_find_zero_bit(bitmap_t map, unsigned int start, unsigned int count)
+{
+	return __bitmap_find_bit(map, start, count, false);
+}
+
+int bitmap_find_one_bit(bitmap_t map, unsigned int start, unsigned int count)
+{
+	return __bitmap_find_bit(map, start, count, true);
+}
+