Move some utility funtions to a new header

1 files changed, 68 insertions, 0 deletions

diff --git a/src/util.h b/src/util.h
new file mode 100644
index 0000000..e36f028
--- /dev/null
+++ b/src/util.h
@@ -0,0 +1,68 @@
+/*
+  Copyright (c) 2012-2014, Matthias Schiffer <mschiffer@universe-factory.net>
+  All rights reserved.
+
+  Redistribution and use in source and binary forms, with or without
+  modification, are permitted provided that the following conditions are met:
+
+    1. Redistributions of source code must retain the above copyright notice,
+       this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright notice,
+       this list of conditions and the following disclaimer in the documentation
+       and/or other materials provided with the distribution.
+
+  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+  FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+  DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+  SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/**
+   \file
+
+   \em Miscellaneous utility functions and macros
+ */
+
+
+#pragma once
+
+/**
+   Returns a pointer to a data structure, given the address of a member contained in the structure
+
+   @param ptr		the address of the member
+   @param type		the type of the container
+   @param member	the name of the member
+
+   \hideinitializer
+ */
+#define container_of(ptr, type, member) ({				\
+			const __typeof__(((type *)0)->member) *_mptr = (ptr); \
+			(type *)((char *)_mptr - offsetof(type, member)); \
+		})
+
+/**
+   Returns the number of elements of an array
+
+   \hideinitializer
+ */
+#define array_size(array) (sizeof(array)/sizeof((array)[0]))
+
+/**
+   Determines how many blocks of a given size \a a are needed to contain some length \a l
+ */
+static inline size_t block_count(size_t l, size_t a) {
+	return (l+a-1)/a;
+}
+
+/**
+   Rounds up a length \a l to the next multiple of a block size \a a
+ */
+static inline size_t alignto(size_t l, size_t a) {
+	return block_count(l, a)*a;
+}