From 1b8fbbd843ddeb5fc81c9303db9c590a436d499b Mon Sep 17 00:00:00 2001
From: William Casarin <jb55@jb55.com>
Date: Mon, 9 Jul 2018 12:10:32 -0700
Subject: progress

---
 ccan/alignof/_info | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 ccan/alignof/_info

(limited to 'ccan/alignof/_info')

diff --git a/ccan/alignof/_info b/ccan/alignof/_info
new file mode 100644
index 0000000..ee2b7ad
--- /dev/null
+++ b/ccan/alignof/_info
@@ -0,0 +1,51 @@
+#include "config.h"
+#include <stdio.h>
+#include <string.h>
+
+/**
+ * alignof - ALIGNOF() macro to determine alignment of a type.
+ *
+ * Many platforms have requirements that certain types must be aligned
+ * to certain address boundaries, such as ints needing to be on 4-byte
+ * boundaries.  Attempting to access variables with incorrect
+ * alignment may cause performance loss or even program failure (eg. a
+ * bus signal).
+ *
+ * There are times which it's useful to be able to programatically
+ * access these requirements, such as for dynamic allocators.
+ *
+ * Example:
+ *	#include <stdio.h>
+ *	#include <stdlib.h>
+ *	#include <ccan/alignof/alignof.h>
+ *
+ *	// Output contains "ALIGNOF(char) == 1"
+ *	// Will also print out whether an onstack char array can hold a long.
+ *	int main(void)
+ *	{
+ *		char arr[sizeof(int)];
+ *
+ *		printf("ALIGNOF(char) == %zu\n", ALIGNOF(char));
+ *		if ((unsigned long)arr % ALIGNOF(int)) {
+ *			printf("arr %p CANNOT hold an int\n", arr);
+ *			exit(1);
+ *		} else {
+ *			printf("arr %p CAN hold an int\n", arr);
+ *			exit(0);
+ *		}
+ *	}
+ *
+ * License: CC0 (Public domain)
+ * Author: Rusty Russell <rusty@rustcorp.com.au>
+ */
+int main(int argc, char *argv[])
+{
+	if (argc != 2)
+		return 1;
+
+	if (strcmp(argv[1], "depends") == 0) {
+		return 0;
+	}
+
+	return 1;
+}
-- 
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