Add a set of simple version comparison helpers

These version helpers help to compare major.minor style version numbers,
without the need for open-coded and error-prone bitshifting, multiplication,
and similar.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Makefile-ccan

@@ -22,7 +22,8 @@ MODS_NORMAL_NO_SRC := alignof \
 	short_types \
 	tcon \
 	tlist \
-	typesafe_cb
+	typesafe_cb \
+	version
 
 # No external dependencies, with C code:
 MODS_NORMAL_WITH_SRC := antithread \

ccan/version/LICENSE

@@ -0,0 +1 @@
+../../licenses/BSD-MIT

ccan/version/_info

@@ -0,0 +1,37 @@
+#include <string.h>
+#include "config.h"
+
+/**
+ * version - helper functions for major.minor-style version numbers
+ *
+ * This code provides some helper functions to deal with version numbers in
+ * the form major.minor.
+ *
+ * Author: Peter Hutterer <peter.hutterer@who-t.net>
+ * Maintainer: Peter Hutterer <peter.hutterer@who-t.net>
+ * License: BSD-MIT
+ *
+ * Example:
+ *	struct version a = version(1, 0);
+ *	struct version b = version(2, 2);
+ *
+ *	if (version_cmp(a, b) < 0)
+ *		printf("Feature supported in version 2.2 but we have %d.%d\n",
+ *			version_major(a), version_minor(a));
+ *
+ *	if (version_cmp(a, version(3, 4)) < 0)
+ *		printf("Feature only supported in version 3.4\n");
+ *
+ */
+int main(int argc, char *argv[])
+{
+	/* Expect exactly one argument */
+	if (argc != 2)
+		return 1;
+
+	if (strcmp(argv[1], "depends") == 0) {
+		return 0;
+	}
+
+	return 1;
+}

ccan/version/test/compile_fail.c

@@ -0,0 +1,11 @@
+#include <ccan/version/version.h>
+#include <ccan/tap/tap.h>
+
+int main(void)
+{
+#ifdef FAIL
+	struct version a;
+	a = 0; /* no direct assignment */
+#endif
+	return 0;
+}

ccan/version/test/run.c

@@ -0,0 +1,69 @@
+#include <ccan/version/version.h>
+#include <ccan/tap/tap.h>
+
+int main(void)
+{
+	struct version a, b;
+
+	plan_tests(26);
+
+	/* cmp with normal versions */
+	a = version(1, 0);
+	b = version(2, 0);
+	ok1(version_cmp(a, b) < 0);
+
+	a = version(1, 1);
+	ok1(version_cmp(a, b) < 0);
+
+	a = version(2, 0);
+	ok1(version_cmp(a, b) == 0);
+
+	a = version(2, 1);
+	ok1(version_cmp(a, b) > 0);
+
+	b = version(2, 1);
+	ok1(version_cmp(a, b) == 0);
+
+	a = version(3, 0);
+	ok1(version_cmp(a, b) > 0);
+
+	a = version(3, 1);
+	ok1(version_cmp(a, b) > 0);
+
+	/* inline cmp */
+	ok1(version_cmp(a, version(1, 0)) > 0);
+	ok1(version_cmp(a, version(1, 1)) > 0);
+	ok1(version_cmp(a, version(3, 0)) > 0);
+	ok1(version_cmp(a, version(3, 1)) == 0);
+	ok1(version_cmp(a, version(3, 2)) < 0);
+	ok1(version_cmp(a, version(4, 0)) < 0);
+	ok1(version_cmp(a, version(4, 1)) < 0);
+
+	/* limits */
+	a = version(0xFFFF, 0xFFFF);
+	b = version(0xFFFE, 0xFFFF);
+	ok1(version_cmp(a, b) > 0);
+	ok1(version_cmp(b, a) < 0);
+
+	b = version(0xFFFF, 0xFFFE);
+	ok1(version_cmp(a, b) > 0);
+	ok1(version_cmp(b, a) < 0);
+
+	b = version(0xFFFF, 0xFFFF);
+	ok1(version_cmp(a, b) == 0);
+	ok1(version_cmp(b, a) == 0);
+
+	b = version(0, 1);
+	ok1(version_cmp(a, b) > 0);
+	ok1(version_cmp(b, a) < 0);
+
+	b = version(1, 0);
+	ok1(version_cmp(a, b) > 0);
+	ok1(version_cmp(b, a) < 0);
+
+	b = version(0, 0);
+	ok1(version_cmp(a, b) > 0);
+	ok1(version_cmp(b, a) < 0);
+
+	return exit_status();
+}

ccan/version/version.h

@@ -0,0 +1,80 @@
+/*****************************************************************************
+ *
+ * version - simple version handling functions for major.minor version
+ * types
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ *
+ ****************************************************************************/
+
+#ifndef CCAN_VERSION_H
+#define CCAN_VERSION_H
+
+#include <stdint.h>
+
+struct version {
+	uint32_t _v; /* major << 16  | minor */
+};
+
+/**
+ * version_major - return the major version of the given struct
+ * @v: the version number to obtain the major number from
+ */
+static inline uint16_t version_major(struct version v) {
+	return (v._v & 0xFFFF0000) >> 16;
+}
+
+/**
+ * version_minor - return the minor version of the given struct
+ * @v: the version number to obtain the minor number from
+ */
+static inline uint16_t version_minor(const struct version v) {
+	return v._v & 0xFFFF;
+}
+
+/**
+ * version - create a new version number
+ * @major: major version number
+ * @minor: minor version number
+ */
+static inline struct version version(uint16_t major, uint16_t minor)
+{
+	struct version v = { ._v = major << 16 | minor };
+	return v;
+}
+
+/**
+ * version_cmp - compare two versions
+ * @a: the first version number
+ * @b: the second version number
+ * @return a number greater, equal, or less than 0 if a is greater, equal or
+ * less than b, respectively
+ *
+ * Example:
+ *	struct version a = version(1, 0);
+ *	struct version b = version(1, 3);
+ *	if (version_cmp(a, b) < 0)
+ *		printf("b is smaller than b\n");
+ */
+static inline int version_cmp(struct version a, struct version b)
+{
+	return  (a._v == b._v) ? 0 : (a._v > b._v) ? 1 : - 1;
+}
+
+#endif /* CCAN_VERSION_H */