helper: add align.h

OpenOCD has to often align values or check for alignment.
Use a dedicated set of macros instead of reinventing the wheel
each time.

Change-Id: Ia58711608aae0801deeaccb5f33148f2073b0bbd
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/6374
Tested-by: jenkins
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>

src/helper/Makefile.am

@@ -15,6 +15,7 @@ noinst_LTLIBRARIES += %D%/libhelper.la
 	%D%/util.c \
 	%D%/jep106.c \
 	%D%/jim-nvp.c \
+	%D%/align.h \
 	%D%/binarybuffer.h \
 	%D%/bits.h \
 	%D%/configuration.h \

src/helper/align.h

@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+/*
+ * The content of this file is mainly copied/inspired from Linux kernel
+ * code in include/linux/align.h and include/uapi/linux/const.h
+ *
+ * Macro name 'ALIGN' conflicts with macOS/BSD file param.h
+ */
+
+#ifndef OPENOCD_HELPER_ALIGN_H
+#define OPENOCD_HELPER_ALIGN_H
+
+#define ALIGN_MASK(x, mask)             \
+({                                      \
+	typeof(mask) _mask = (mask);        \
+	((x) + _mask) & ~_mask;             \
+})
+
+/* @a is a power of 2 value */
+#define ALIGN_UP(x, a)          ALIGN_MASK(x, (typeof(x))(a) - 1)
+#define ALIGN_DOWN(x, a)        ((x) & ~((typeof(x))(a) - 1))
+#define IS_ALIGNED(x, a)        (((x) & ((typeof(x))(a) - 1)) == 0)
+
+#define IS_PWR_OF_2(x)                  \
+({                                      \
+	typeof(x) _x = (x);                 \
+	_x == 0 || (_x & (_x - 1)) == 0;    \
+})
+
+#endif /* OPENOCD_HELPER_ALIGN_H */